MyBatis sample application for connecting to OceanBase Database

This topic describes how to build an application by using the MyBatis framework and OceanBase Database. The application can perform basic operations such as creating tables, inserting data, and querying data.

Download the Java OceanBase MyBatis sample project

Prerequisites

• You have installed OceanBase Database.
• You have installed JDK 1.8 and Maven.
• You have installed IntelliJ IDEA.

Procedure

1. Obtain the connection string of OceanBase Database.
2. Import the java-oceanbase-mybatis project into IntelliJ IDEA.
3. Modify the database connection information in the java-oceanbase-mybatis project.
4. Run the java-oceanbase-mybatis project.

Step 1: Obtain the connection string of OceanBase Database

1. Contact the OceanBase Database deployment personnel or administrator to obtain the corresponding database connection string.

   obclient -hxx.xx.xx.xx -P2883 -uroot@sys#cluster -p**** -A
   

2. Fill in the corresponding information in the URL below based on the deployed OceanBase Database.

   Note

   The URL information is required in the jdbc.properties file.

   jdbc:oceanbase://host:port/schema_name?user=$user_name&password=$password
   

   Parameter description:

   • host: the IP address for connecting to OceanBase Database. For ODP connection, it is the IP address of an ODP. For direct connection, it is the IP address of an OBServer node.
   • port: the port for connecting to OceanBase Database. For ODP connection, the default value is 2883, which can be customized when ODP is deployed. For direct connection, the default value is 2881, which can be customized when OceanBase Database is deployed.
   • schema_name: the name of the schema to be accessed.
   • user_name: specified by the -u parameter. The format is user@tenant#cluster name or username@SERVICE:service name. When the format user@tenant#cluster name is used, the default tenant is sys and the administrator user is root. When directly connecting to the database, the cluster name can be omitted. When connecting through ODP, the cluster name must be specified.
   • password: the password of the account.

Step 2: Import the java-oceanbase-mybatis project into IntelliJ IDEA

1. Open IntelliJ IDEA and select File > Open....

   

2. In the Open File or Project window that appears, select the project file and click OK to import the project file.

3. IntelliJ IDEA automatically identifies various files in the project and displays the project structure, file list, module list, and dependency relationships in the Project tool window. The Project tool window is usually located on the left side of the IntelliJ IDEA interface and is open by default. If the Project tool window is closed, you can click View > Tool Windows > Project in the menu bar or press the shortcut key Alt + 1 to reopen it.

   Note

   When you import a project using IntelliJ IDEA, it automatically detects the pom.xml file in the project, downloads the required dependency libraries based on the described dependencies in the file, and adds them to the project.

4. View the project.

Step 3: Modify the database connection information in the java-oceanbase-mybatis project

Modify the database connection information in the jdbc.properties file based on the information obtained in Step 1: Obtain the connection string of OceanBase Database.

Example:

• The name of the database driver is com.oceanbase.jdbc.Driver.
• The IP address of the OBServer node is 10.10.10.1.
• The access port is 2881.
• The name of the schema to be accessed is test.
• The URL extra connection attributes are useServerPrepStmts=true&rewriteBatchedStatements=true.
• The tenant connection account is root@mysql001. mysql001 is a MySQL user tenant created in OceanBase Database, and root is the username of the mysql001 tenant.
• The password is ******.

Sample code:

jdbc.driver=com.oceanbase.jdbc.Driver
jdbc.url=jdbc:oceanbase://10.10.10.1:2881/sys?useServerPrepStmts=true&rewriteBatchedStatements=true
jdbc.username=root@mysql001
jdbc.password=******

Step 4: Run the java-oceanbase-mybatis project

Run path

1. In the project structure, go to src > test > java and find the TestMybatis.java file.
2. In the tool menu bar, select Run(U) > Run > TestMybatis, or click the green triangle in the upper right corner to run it.
3. View the log information and output results in the IDEA console.

Run result

1. The output result of the testUserMapper method is as follows:

   User{id=2, name='update'}
   User{id=3, name='insert'}
   User{id=4, name='insert'}
   User{id=5, name='insert'}
   User{id=6, name='insert'}
   User{id=7, name='insert'}
   User{id=8, name='insert'}
   User{id=9, name='insert'}
   User{id=10, name='insert'}
   usersByPage = [User{id=5, name='insert'}, User{id=6, name='insert'}, User{id=7, name='insert'}]
   

2. The output result of the testSqlSession method is as follows:

   User{id=2, name='update'}
   User{id=3, name='insert'}
   User{id=4, name='insert'}
   User{id=5, name='insert'}
   User{id=6, name='insert'}
   User{id=7, name='insert'}
   User{id=8, name='insert'}
   User{id=9, name='insert'}
   User{id=10, name='insert'}
   

3. The output result of the testAppMapper method is as follows:

   App{id=2, name='update'}
   App{id=3, name='insert3'}
   App{id=4, name='insert4'}
   App{id=5, name='insert5'}
   App{id=6, name='insert6'}
   App{id=7, name='insert7'}
   App{id=8, name='insert8'}
   App{id=9, name='insert9'}
   App{id=10, name='insert10'}
   pageList = Page{count=true, pageNum=2, pageSize=3, startRow=3, endRow=6, total=9, pages=3, reasonable=false, pageSizeZero=true}[App{id=5, name='insert5'}, App{id=6, name='insert6'}, App{id=7, name='insert7'}]
   

4. The complete output result is as follows:

   User{id=2, name='update'}
   User{id=3, name='insert'}
   User{id=4, name='insert'}
   User{id=5, name='insert'}
   User{id=6, name='insert'}
   User{id=7, name='insert'}
   User{id=8, name='insert'}
   User{id=9, name='insert'}
   User{id=10, name='insert'}
   usersByPage = [User{id=5, name='insert'}, User{id=6, name='insert'}, User{id=7, name='insert'}]
   App{id=2, name='update'}
   App{id=3, name='insert3'}
   App{id=4, name='insert4'}
   App{id=5, name='insert5'}
   App{id=6, name='insert6'}
   App{id=7, name='insert7'}
   App{id=8, name='insert8'}
   App{id=9, name='insert9'}
   App{id=10, name='insert10'}
   pageList = Page{count=true, pageNum=2, pageSize=3, startRow=3, endRow=6, total=9, pages=3, reasonable=false, pageSizeZero=true}[App{id=5, name='insert5'}, App{id=6, name='insert6'}, App{id=7, name='insert7'}]
   User{id=2, name='update'}
   User{id=3, name='insert'}
   User{id=4, name='insert'}
   User{id=5, name='insert'}
   User{id=6, name='insert'}
   User{id=7, name='insert'}
   User{id=8, name='insert'}
   User{id=9, name='insert'}
   User{id=10, name='insert'}
   

FAQs

1. Connection timeout

If you encounter a connection timeout issue, you can configure the connection timeout parameter in the JDBC URL:

jdbc:mysql://host:port/database?connectTimeout=30000&socketTimeout=60000

2. Character set issues

To ensure correct character encoding, set the appropriate character set parameter in the JDBC URL:

jdbc:mysql://host:port/database?characterEncoding=utf8&useUnicode=true

3. SSL connection

To enable an SSL connection to OceanBase Database, add the following parameter to the JDBC URL:

jdbc:mysql://host:port/database?useSSL=true&requireSSL=true

4. Special characters in account or password

If the username or password contains special characters (such as #), you need to URL-encode them:

String encodedPassword = URLEncoder.encode(password, "UTF-8");

Project code introduction

Click java-oceanbase-mybatis to download the project code, which is a compressed package named java-oceanbase-mybatis.

After decompressing it, you will find a folder named java-oceanbase-mybatis. The directory structure is as follows:

│--pom.xml
│
├─.idea
│
├─src
│  ├─main
│  │  ├─java
│  │  │  └─com
│  │  │      └─oceanbase
│  │  │          ├─mapper
│  │  │          │------IAppMapper.java
│  │  │          │------IUserMapper.java
│  │  │          │
│  │  │          └─pojo
│  │  │              │---App.java
│  │  │              └─--User.java
│  │  │
│  │  └─resources
│  │      │--jdbc.properties
│  │      │--mybatis-config.xml
│  │      │
│  │      └─com
│  │          └─oceanbase
│  │              └─mapper
│  │                  └─---IUserMapper.xml
│  │
│  └─test
│      └─java
│          └─---TestMybatis.java
│
└─target

File description:

• pom.xml: The configuration file of the Maven project, which contains information about the project's dependencies, plugins, and build process.
• .idea: A directory used by the IDE (Integrated Development Environment) to store project-related configuration information.
• src: A directory typically used to store the source code of the project.
• main: A directory for storing the main source code and resource files.
• java: A directory for storing Java source code.
• com: The root directory for storing Java packages.
• oceanbase: The root directory for storing the project.
• mapper: A directory for storing MyBatis Mapper interfaces and XML files.
• IAppMapper.java: A file for storing the application data access layer interface.
• IUserMapper.java: A file for storing the user data access layer interface.
• pojo: A directory for storing JavaBeans or entity classes.
• App.java: A file for storing the application entity class.
• User.java: A file for storing the user entity class.
• resources: A directory for storing resource files, such as configuration files and SQL files.
• jdbc.properties: A configuration file for storing database connection information.
• mybatis-config.xml: A file for storing MyBatis configuration.
• IUserMapper.xml: An XML file for storing the user data access layer configuration.
• test: A directory for storing test code and resource files.
• TestMybatis.java: A Java file for storing test code for MyBatis.
• target: A directory for storing compiled Class files, JAR packages, and other files.

pom.xml

The content of the pom.xml configuration file is as follows:

1. File declaration statement.

   Declares that the file is an XML file using XML version 1.0 and character encoding UTF-8.

   Sample code:

   <?xml version="1.0" encoding="UTF-8"?>
   

2. Configure the namespace and model version of the POM.

   1. Use xmlns to specify the POM namespace as http://maven.apache.org/POM/4.0.0.
   2. Use xmlns:xsi to specify the XML namespace as http://www.w3.org/2001/XMLSchema-instance.
   3. Use xsi:schemaLocation to specify the POM namespace as http://maven.apache.org/POM/4.0.0 and the location of the POM XSD file as http://maven.apache.org/xsd/maven-4.0.0.xsd.
   4. Use <modelVersion> to specify the POM model version used by the POM file as 4.0.0.

   Sample code:

   <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
     <modelVersion>4.0.0</modelVersion>
   </project>
   

3. Configure basic information.

   1. Use <groupId> to specify the project identifier as com.oceanbase.example.
   2. Use <artifactId> to specify the project dependency as java-oceanbase-mybatis.
   3. Use <version> to specify the project version as 1.0-SNAPSHOT.

   Sample code:

   <groupId>com.oceanbase.example</groupId>
   <artifactId>java-oceanbase-mybatis</artifactId>
   <version>1.0-SNAPSHOT</version>
   

4. Use <build> to define the project build process.

   1. Use <plugins> to specify the plugins configured in the project.
   2. Use <plugin> to specify a plugin configured in the project.
   3. Use <groupId> to specify the project identifier as org.apache.maven.plugins.
   4. Use <artifactId> to specify the project dependency as maven-compiler-plugin.
   5. Use <configuration> to specify the parameters of the configured plugin.
   6. Use <source> to specify the compiler source code version as 8.
   7. Use <target> to specify the compiler source code version as 8.

   Sample code:

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>8</source>
                    <target>8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
   

5. Use <dependencies> to define the components that the project depends on.

   1. Specify the organization of the dependency item as com.oceanbase, the name as oceanbase-client, and the version as 2.4.2.

      Sample code:

          <dependencies>
          <dependency>
              <groupId>com.oceanbase</groupId>
              <artifactId>oceanbase-client</artifactId>
              <version>2.4.2</version>
          </dependency>
          </dependencies>
      

   2. Specify the test architecture of the dependency item as junit, the name as junit, and the version as 4.10.

      Sample code:

          <dependencies>
          <dependency>
              <groupId>junit</groupId>
              <artifactId>junit</artifactId>
              <version>4.10</version>
          </dependency>
          </dependencies>
      

   3. Specify the architecture of the dependency item as org.mybatis, the name as mybatis, and the version as 3.5.9.

      Sample code:

          <dependencies>
          <dependency>
              <groupId>org.mybatis</groupId>
              <artifactId>mybatis</artifactId>
              <version>3.5.9</version>
          </dependency>
          </dependencies>
      

   4. Specify the plugin of the dependency item as com.github.pagehelper, the name as pagehelper, and the version as 5.3.0.

      Sample code:

          <dependencies>
          <dependency>
              <groupId>com.github.pagehelper</groupId>
              <artifactId>pagehelper</artifactId>
              <version>5.3.0</version>
          </dependency>
          </dependencies>
      

jdbc.properties

jdbc.properties is a property file that stores configuration information related to database connections, including the database URL, username, and password. The code contains the following content:

• jdbc.driver: the class name of the database driver program, used to load the database driver program.
• jdbc.url: the URL address of the database, used to specify the database to connect to.
• jdbc.username: the username of the database, used to verify the database connection.
• jdbc.password: the password of the database, used to verify the database connection.

Sample code:

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://host:port/TEST?useServerPrepStmts=true&rewriteBatchedStatements=true
jdbc.username=user_name
jdbc.password=******

Introduction to mybatis-config.xml

The mybatis-config.xml file is used to configure global properties and plugins of the MyBatis framework.

The code in the mybatis-config.xml file mainly includes the following parts:

1. File declaration.

   This declaration indicates that the file is an XML file and specifies that the current document is a MyBatis configuration file, using XML version 1.0 and character encoding UTF-8. The version number is 3.0, the language is English, and the DTD (Document Type Definition) file provided by the official MyBatis website is used for validation.

   The declaration includes the following parts:

   • version: specifies the version of the XML file.
   • encoding: specifies the encoding method of the XML file.
   • DOCTYPE: declares the type as a document type declaration.
   • configuration: specifies the document type as a MyBatis configuration file.
   • PUBLIC: specifies the document type as a public document type.
   • mybatis.org: represents the official website of MyBatis.
   • DTD Config 3.0: represents the version number of the MyBatis configuration file.
   • EN: represents the language of the document type as English.

   Sample code:

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
   

2. Specify the path and filename of the property file to be loaded.

   <properties resource="jdbc.properties"></properties>
   

3. Configure the global settings of MyBatis.

   The content of the global settings of MyBatis includes the following parts:

   • setting: used to configure individual settings, such as cache and log.
   • cacheEnabled: used to enable or disable the cache feature, set to true.
   • lazyLoadingEnabled: used to enable or disable the lazy loading feature, set to true.
   • aggressiveLazyLoading: used to enable or disable the aggressive lazy loading feature, set to true.
   • multipleResultSetsEnabled: used to configure whether to enable support for multiple result sets, set to true.
   • useColumnLabel: used to configure whether to use column labels as column names in the result set, set to true.
   • useGeneratedKeys: used to configure whether to use automatically generated primary keys, set to true.
   • autoMappingBehavior: used to configure the handling behavior of auto-mapping, set to PARTIAL.
   • defaultExecutorType: used to configure the default executor type, set to SIMPLE.
   • mapUnderscoreToCamelCase: used to configure whether to convert underscores in database column names to camel case in Java object property names, set to true.
   • localCacheScope: used to configure the scope of the local cache, set to SESSION.
   • jdbcTypeForNull: used to configure the JDBC type to be used when handling null values, set to NULL.

   Note

   The child elements of the settings element are optional and can be added or removed as needed.

   Sample code:

   <settings>
       <!-- Enable or disable caching for global mappers. -->
       <setting name="cacheEnabled" value="true"/>
       <!-- Enable or disable lazy loading globally. When disabled, all associated objects are loaded immediately. -->
       <setting name="lazyLoadingEnabled" value="true"/>
       <!-- When enabled, objects with delayed loading properties will fully load any properties when called. Otherwise, each attribute will be loaded as needed. -->
       <setting name="aggressiveLazyLoading" value="true"/>
       <!-- Allow a single SQL statement to return multiple datasets (depending on driver compatibility) default: true -->
       <setting name="multipleResultSetsEnabled" value="true"/>
       <!-- Can column aliases be used (depending on driver compatibility) default: true -->
       <setting name="useColumnLabel" value="true"/>
       <!-- Allow JDBC to generate primary keys. Drive support is required. If set to true, this setting will force the use of the generated primary key, and some drives may not be compatible but can still be executed. default:false -->
       <setting name="useGeneratedKeys" value="true"/>
       <!-- Specify how MyBatis automatically maps the columns of the data base table NONE: Not Implicit PART: Partial FULL: All -->
       <setting name="autoMappingBehavior" value="PARTIAL"/>
       <!-- This is the default execution type (SIMPLE: simple; REUSE: executor may repeatedly use prepared statements; BATCH: executor can repeatedly execute statements and batch updates) -->
       <setting name="defaultExecutorType" value="SIMPLE"/>
       <!-- Convert fields using camel naming. -->
       <setting name="mapUnderscoreToCamelCase" value="true"/>
       <!-- Set the local cache range session: there will be data sharing statement: statement range (so there will be no data sharing) defalut: session -->
       <setting name="localCacheScope" value="SESSION"/>
       <!-- When the JDBC type is set to null, some drivers need to specify a value, default: Other, and there is no need to specify a type when inserting null values -->
       <setting name="jdbcTypeForNull" value="NULL"/>
   </settings>
   

4. Configure plugins of MyBatis.

   The content of the plugins of MyBatis includes the following parts:

   • plugin: used to configure individual plugins.
   • property: used to specify the properties of the plugin.
   • interceptor: used to specify the implementation class of the plugin.
   • helperDialect: used to specify the selected database.
   • offsetAsPageNum: indicates whether to use the offset parameter as the pageNum parameter.
   • rowBoundsWithCount: indicates whether to perform a count query.
   • pageSizeZero: indicates whether to support queries with pageSize 0.
   • reasonable: indicates whether to enable reasonable query optimization.
   • params: indicates the mapping relationship between the parameter name and parameter value for passing pagination parameters.
   • supportMethodsArguments: indicates whether to support using method parameters to pass pagination parameters.
   • returnPageInfo: indicates the return value type.

   Sample code:

   <plugin interceptor="com.github.pagehelper.PageInterceptor">
      <!-- this parameter indicates which database to connect to -->
      <!--MySQLMode dialect<property name="helperDialect" value="mysql"/>-->
      <!--OracleMode dialect -->
      <property name="helperDialect" value="mysql"/>
      <!-- This parameter defaults to false. When set to true, the first parameter offset of RowBounds will be used as the pageNum page number, similar to the pageNum effect in startPage -->
      <property name="offsetAsPageNum" value="true"/>
      <!-- This parameter defaults to false, and when set to true, using RowBounds pagination will result in a count query -->
      <property name="rowBoundsWithCount" value="true"/>
      <!-- When set to true, if pageSize=0 or RowBounds. limit=0, all results will be queried (equivalent to not executing a pagination query, but the returned results are still of type Page) -->
      <property name="pageSizeZero" value="true"/>
      <!-- Version 3.3.0 is available - pagination parameter rationalization is disabled by default as false. When rationalization is enabled, if pageNum<1, the first page will be queried, and if pageNum>pages, the last page will be queried. Rationalization of paging parameters. When rationalization is disabled, if pageNum<1 or pageNum>pages returns empty data -->
      <property name="reasonable" value="false"/>
      <!-- Version 3.5.0 is available - In order to support the startPage (Object params) method, a 'params' parameter has been added to configure parameter mapping, which can be used to retrieve values from Map or ServletRequest. PageNum, pageSize, count, pageSizeZero, reasonable, orderBy can be configured. If mapping is not configured, the default value will be used. If you do not understand the meaning, do not copy this configuration casually -->
      <property name="params" value="pageNum=start;pageSize=limit;"/>
      <!-- Support passing paging parameters through Mapper interface parameters -->
      <property name="supportMethodsArguments" value="true"/>
      <!-- Always always returns PageInfo type, check to check if the return type is PageInfo, and none returns Page -->
      <property name="returnPageInfo" value="check"/>
   </plugin>
   

5. Configure the environment of MyBatis. The content of the environment of MyBatis includes the following parts:

   • environment: used to configure individual environments.
   • transactionManager: used to specify the implementation class of the transaction manager.
   • dataSource: used to specify the implementation class of the data source.
   • property: specifies the class name of the database driver.

   Note

   In other configuration elements of MyBatis, you can use the ${} placeholder to reference data sources, transaction managers, and executors configured in the environment.

   Sample code:

   <environments default="development">
       <environment id="development">
         <transactionManager type="JDBC"/>
           <dataSource type="POOLED">
               <property name="driver" value="${jdbc.driver}"/>
               <property name="url" value="${jdbc.url}"/>
               <property name="username" value="${jdbc.username}"/>
               <property name="password" value="${jdbc.password}"/>
           </dataSource>
       </environment>
   </environments>
   

6. Configure the mapper of MyBatis.

   The common elements of the mapper of MyBatis are as follows:

   • resource: used to specify the path and filename of the XML configuration file of the mapper.
   • class: used to specify the fully qualified name of the Java class of the mapper.

   Note

   If you use an XML configuration file, you need to specify the path and filename of the XML file in the mapper element. If you use a Java interface, you need to specify the fully qualified name of the Java class in the mapper element.

   Sample code:

   <mappers>
     <!-- IUserMapper.xml mapping file -->
     <mapper resource="com/alipay/oceanbase/mapper/IUserMapper.xml"></mapper>
     <!-- IAppMapper mapping class -->
     <mapper class="com.oceanbase.mapper.IAppMapper"></mapper>
   </mappers>
   

Introduction to the IUserMapper.xml file

The IUserMapper.xml file is a mapping file that defines SQL statements related to the user object. The file defines a namespace named IUserMapper to store SQL statements related to the user object.

The IUserMapper.xml file contains the following main sections:

1. File declaration statements. The XML declaration specifies the version and encoding of the XML file. The DTD declaration introduces the MyBatis DTD file. Sample code:

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
   

2. Configure the mapping relationship with the IUserMapper.java file.

   1. Define the namespace for the Mapper interface to correspond with the Mapper interface in the Java code.
   2. Create an SQL statement named insertUser to insert a record into the test_user table, including the id and name fields with values #{id} and #{name} respectively. The parameterType attribute specifies the parameter type as com.oceanbase.pojo.User.
   3. Create an SQL statement named deleteUser to delete a record from the test_user table based on the value of the id field, which is #{id}.
   4. Create an SQL statement named updateUser to update a record in the test_user table, setting the name field to #{name} based on the value of the id field, which is #{id}.
   5. Create an SQL statement named selectUsers to query all user records from the test_user table.
   6. Create an SQL statement named selectUserByPage to query user objects from the test_user table for a specified page. Use subqueries and the rownum field for pagination, where #{pageNum} and #{pageSize} represent the current page number and the number of records per page, respectively.

   Sample code:

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE mapper
           PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
           "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
   <mapper namespace="com.oceanbase.mapper.IUserMapper">
       <insert id="insertUser" parameterType="com.oceanbase.pojo.User">
           INSERT INTO test_user (id,name) VALUES (#{id},#{name})
       </insert>
       <delete id="deleteUser" parameterType="long">
           DELETE FROM test_user WHERE id = #{id}
       </delete>
       <update id="updateUser" parameterType="com.oceanbase.pojo.User">
           UPDATE test_user SET name = #{name} WHERE id = #{id}
       </update>
       <select id="selectUsers" resultType="com.oceanbase.pojo.User">
           SELECT id,name FROM test_user
       </select>
       <!--    There are two ways to paginate queries: 1. Use the pagehelper plugin; 2. Use SQL statements to paginate  -->
       <!-- SQL statement pagination: Oracle-compatible mode does not support the limit keyword, and instead uses the unique field 'rownum'-->
       <select id="selectUserByPage" resultType="com.oceanbase.pojo.User">
           select id,name from ( select row_.*, rownum rownum_ from ( select * from test_user ) row_ where rownum
           <![CDATA[ <= ]]>  #{pageNum} * #{pageSize} ) where rownum_ <![CDATA[ >]]>  ( #{pageNum}- 1) * #{pageSize}
       </select>
   </mapper>
   

Introduction to the IAppMapper.java file

The IAppMapper.java file defines SQL mapping relationships.

The IAppMapper.java file contains the following main sections:

1. Define the Mapper package.

   Declare the package name of the current file as com.oceanbase.mapper. The Mapper package includes the following interfaces and classes:

   • App interface: Represents the mapping to a database table, enabling data read and write operations.
   • org.apache.ibatis.annotations.*: Used to import MyBatis annotation classes.
   • java.util.List: Used to import the List class from the java.util package. Sample code:

   package com.oceanbase.mapper;
   import com.oceanbase.pojo.App;
   import org.apache.ibatis.annotations.*;
   import java.util.List;
   

2. Define the IAppMapper interface. The IAppMapper interface defines the MyBatis Mapper interface. The Mapper interface defines SQL mapping relationships to perform database operations such as insert, update, delete, and query. Specifically, the IAppMapper interface defines methods for inserting, updating, deleting, and querying data in the test_app table, including:

   • @Insert method: Used to insert data into the database.
   • @Update method: Used to update data in the database.
   • @Delete method: Used to delete data from the database.
   • @Select method: Used to query data from the database.
   • @Results method: Specifies the mapping of query results, mapping fields in the query results to properties of Java objects. Database operations include:

   1. Insert data Map the App object to a record in the test_app table. Use #{property name} to represent the property values of the App object. The Integer return value indicates the automatically generated ID returned after the SQL statement inserts data, which corresponds to the ID field in the test_app table.

      @Insert("insert into test_app(id,name) values(#{id},#{name})")
      Integer insertApp(App app);
      

   2. Delete data Delete data from the test_app table where the ID is equal to #{id}.

      @Delete("delete from test_app  where id =#{id}")
      Integer deleteApp(Long id);
      

   3. Update data Perform an update operation on the records in the test_app table.

      @Update("update test_app set name= #{name} where id = #{id}")
      Integer updateApp(App user);
      

   4. Query and map data Query all data from the test_app table. Use the @Results and @Result annotations to map the query results to the id and name properties of the App object. Return a list of App objects.

      @Update("update test_app set name= #{name} where id = #{id}")
      Integer updateApp(App user);
      @Results({
          @Result(id = true, column = "id", property = "id"),
          @Result(column = "name", property = "name")
          })
      List<App> selectApps();
      

   Sample code:

   package com.oceanbase.mapper;
   import com.oceanbase.pojo.App;
   import org.apache.ibatis.annotations.*;
   import java.util.List;
   public interface IAppMapper {
       @Insert("insert into test_app(id,name) values(#{id},#{name})")
       Integer insertApp(App app);
   
       @Delete("delete from test_app  where id =#{id}")
       Integer deleteApp(Long id);
   
       @Update("update test_app set name= #{name} where id = #{id}")
       Integer updateApp(App user);
   
       @Select("select * from test_app")
       @Results({
               @Result(id = true, column = "id", property = "id"),
               @Result(column = "name", property = "name")
       })
       List<App> selectApps();
   }
   

Introduction to the IUserMapper.java file

The IUserMapper.java file defines methods for database operations.

The IUserMapper.java file contains the following main sections:

1. Import other classes and interfaces.

   Declare the interfaces and classes included in the current file:

   • User class: Represents the user object.
   • org.apache.ibatis.annotations.Param class: A parameter annotation in the MyBatis framework.
   • List interface: Represents a list type. Sample code:

   package com.oceanbase.mapper;
   import com.oceanbase.pojo.User;
   import org.apache.ibatis.annotations.Param;
   import java.util.List;
   

2. Define the IUserMapper interface.

   Define an interface named IUserMapper that includes methods for inserting, deleting, updating, and querying user data, as well as methods for paginated queries. Use JavaDoc comments and the @Param annotation to improve code readability and maintainability. Sample code:

    public interface IUserMapper {
   
        Integer insertUser(User user);
   
        Integer deleteUser(Long id);
   
        Integer updateUser(User user);
   
        List<User> selectUsers();
   
        public List<User> selectUserByPage(@Param("user") User user, @Param("pageNum") Integer pageNum,
                                        @Param("pageSize") Integer pageSize);
    }
   

App.java code introduction

The App.java file is used to represent the App application object. It includes two properties, id and name. The class also defines access methods for the properties, a constructor, and a toString method for converting the object to a string.

The App.java file contains the following code:

1. Define the pojo package. Declare the package name of the current file as com.oceanbase.pojo.
2. Define the App class.
   1. Define a class App with two private properties, id and name, and a parameterless constructor public App(){}.
   2. Define a parameterized constructor public App(Long id, String name) to create an application object with the specified id and name.
   3. Define getId, setId, getName, and setName methods to get and set the application name. The setName method returns the name of the application.
   4. Override the toString method to convert the application object to a string representation for easier output and debugging.

Code:

   package com.oceanbase.pojo;

   public class App {
       private Long id;
       private String name;

       public App() {
       }

       public App(Long id, String name) {
            this.id = id;
           this.name = name;
       }

       public Long getId() {
           return id;
       }

       public void setId(Long id) {
           this.id = id;
       }

       public String getName() {
           return name;
       }

       public void setName(String name) {
           this.name = name;
       }

       @Override
       public String toString() {
           return "App{" +
                   "id=" + id +
                   ", name='" + name + '\'' +
                   '}';
       }
   }

User.java code introduction

The User.java file is used to represent the user object. It includes two properties, id and name. The class also defines access methods for the properties, a constructor, and a toString method for converting the object to a string. The creation of this class is similar to the creation of the App.java file above.

Code:

package com.oceanbase.pojo;

public class User {
    private Long id;
    private String name;

    public User() {
    }

    public User(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

TestMyBatis.java file introduction

The TestMyBatis.java file is used to demonstrate how to perform data operations using MyBatis. It tests the basic functionality of the MyBatis framework, the execution of SQL statements, the invocation of Mapper interfaces, and the parameters and return values of SQL statements.

1. Import other classes and interfaces.

   The following classes and interfaces are imported:

   • IAppMapper interface: defines SQL statements related to App objects.
   • IUserMapper interface: defines SQL statements related to User objects.
   • App class: an App object used to test the execution of SQL statements.
   • User class: a User object used to test the execution of SQL statements.
   • PageHelper plugin: implements pagination query functionality.
   • PageInfo plugin: encapsulates the results of pagination queries.
   • Resources class: loads the MyBatis configuration file.
   • SqlSession class: executes SQL statements and manages transactions.
   • SqlSessionFactory class: creates a SqlSession object.
   • SqlSessionFactoryBuilder class: creates a SqlSessionFactory object.
   • org.junit.Test: an annotation from the JUnit testing framework, used to mark test methods.
   • IOException class: represents errors during input/output operations.
   • SQLException class: represents errors during SQL operations.
   • Statement interface: executes SQL statements and returns results.
   • java.util.List interface: represents an ordered collection where elements can be repeated.

   Code:

   import com.oceanbase.mapper.IAppMapper;
   import com.oceanbase.mapper.IUserMapper;
   import com.oceanbase.pojo.App;
   import com.oceanbase.pojo.User;
   import com.github.pagehelper.PageHelper;
   import com.github.pagehelper.PageInfo;
   import org.apache.ibatis.io.Resources;
   import org.apache.ibatis.session.SqlSession;
   import org.apache.ibatis.session.SqlSessionFactory;
   import org.apache.ibatis.session.SqlSessionFactoryBuilder;
   import org.junit.Test;
   import java.io.IOException;
   import java.sql.SQLException;
   import java.sql.Statement;
   import java.util.List;
   

2. Define the testUserMapper method.

   The testUserMapper method tests the execution of SQL statements defined in the Mapper interface of the User object.

   1. Use the build() method of the SqlSessionFactoryBuilder class to create a SqlSessionFactory instance. This instance manages the creation and destruction of SqlSession instances.
   2. Use the openSession() method of the SqlSessionFactory class to create a SqlSession instance. This instance can execute various SQL statements, including queries, inserts, updates, and deletes.
   3. Use the getConnection() method of the SqlSession instance to obtain a Connection instance. This instance can perform various database operations.
   4. Use the createStatement() method of the Connection instance to create a Statement instance. Execute SQL statements in sequence.
   5. Use the execute() method of the Statement object to execute an SQL statement that deletes the test_user table.
   6. Use the execute() method of the Statement object to create the test_user table. This table contains two fields: id (type number(20)) as the primary key, and name (type varchar2(100)).
   7. Use the getMapper() method of the SqlSession instance to obtain an instance of the IUserMapper interface. Define various database operation methods.
   8. Use a for loop to insert 10 records into the test_user table. In each iteration, create a new User object, use the insertUser() method of the Mapper interface to execute the insert operation. The result of the insert operation will be stored in the insertResult variable.
   9. Perform delete, update, and query operations on the data in the test_user table, and finally use the forEach() method to print the information of each user in the user list.
   10. Create a user named insert, use the selectUserByPage() method to query all user data with the name "insert" in the test_user table, and return the user list for the specified page. The query is for page 2, displaying 3 records per page. Print these user data to the console. Close the Statement and SqlSession instances, commit the transaction, and release resources.

   Code:

       public void testUserMapper() throws SQLException, IOException {
           //mybatis xml usecases
           SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
           SqlSession sqlSession = sqlSessionFactory.openSession();
           Statement statement = sqlSession.getConnection().createStatement();
           try {
               statement.execute("drop table test_user");
           } catch (SQLException ex) {
           } finally {
               statement.execute("create table test_user(id number(20) primary key,name varchar2(100))");
           }
           IUserMapper mapper = sqlSession.getMapper(IUserMapper.class);
           //insert 10 users
           for (int i = 1; i <= 10; i++) {
               User user = new User((long) i, "insert");
               Integer insertResult = mapper.insertUser(user);
           }
           //delete id==1
           Integer deleteResult = mapper.deleteUser(1L);
           //update id==2L name=update
           User updateUser = new User(2L, "update");
           Integer updateResult = mapper.updateUser(updateUser);
           //selectUsers query all
           List<User> userList = mapper.selectUsers();
           userList.forEach(System.out::println);
           //selectUsersByPage: use the rownum keyword in SQL statements to manually perform pagination queries,
           // example: data on page 2 (3 items per page)
           User user = new User();
           user.setName("insert");
           List<User> usersByPage = mapper.selectUserByPage(user, 2, 3);
           System.out.println("usersByPage = " + usersByPage);
           statement.close();
           sqlSession.commit();
           sqlSession.close();
       }
   

3. Define the testSqlSession method.

   The testSqlSession method is used to test the basic features of the SqlSession object, including executing SQL statements, committing transactions, and closing the SqlSession object.

   1. Use the build() method of the SqlSessionFactoryBuilder class to create a SqlSessionFactory instance. This instance is used to manage the creation and destruction of SqlSession instances.
   2. Use the openSession() method of the SqlSessionFactory instance to create a SqlSession instance. This instance can execute various SQL statements, including queries, inserts, updates, and deletes.
   3. Use the getConnection() method of the SqlSession instance to obtain a Connection instance. This instance can execute various database operations.
   4. Use the createStatement() method of the Connection instance to create a Statement instance. Execute SQL statements in sequence.
   5. Use the execute() method of the Statement object to execute an SQL statement that deletes the test_user table.
   6. Use the execute() method of the Statement object to create the test_user table. This table contains two fields: one is id, of type number(20), which serves as the primary key; the other is name, of type varchar2(100).
   7. Use a for loop to insert 10 records into the test_user table. In each iteration of the loop, create a new User object, use the insertUser() method of the Mapper interface to execute the insert operation, and store the result of the insert operation in the insertResult variable.
   8. Use the delete() method of the sqlSession object to execute the delete operation. Set the deletion condition by passing in the parameter 1L. Store the result of the delete operation in the deleteResult variable.
   9. Use the sqlSession object to execute a database update operation. Create a User object, call the update method, and pass in the SQL statement identifier and parameter object to complete the update operation. The specific SQL statements and parameter mapping relationships can be found in the XML configuration file of the "com.oceanbase.mapper.IUserMapper" interface. Store the result of the update operation in the updateResult variable.
   10. Use the openSession() method of the SqlSessionFactory instance to create a SqlSession instance. Execute a query operation through this instance and store the query result in the userList variable. Finally, use the forEach method to traverse the userList and output it to the console.
   11. Close the Statement object in the database connection using statement.close(). Then, use sqlSession.commit() to commit the transaction and persist all modifications to the database. Finally, use sqlSession.close() to close the SqlSession object, release the related resources, and close the connection to the database.

   Sample code:

       public void testSqlSession() throws SQLException, IOException {
           //SqlSession usecases
           SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
           SqlSession sqlSession = sqlSessionFactory.openSession();
           Statement statement = sqlSession.getConnection().createStatement();
           try {
               statement.execute("drop table test_user");
           } catch (SQLException ex) {
           } finally {
               statement.execute("create table test_user(id number(20) primary key,name varchar2(100))");
           }
           //insert
           for (int i = 1; i <= 10; i++) {
               User user = new User((long) i, "insert");
               //Integer insertResult = mapper.insertUser(user);
               int insertResult = sqlSession.insert("com.oceanbase.mapper.IUserMapper.insertUser", user);
           }
           //delete
           int deleteResult = sqlSession.delete("com.oceanbase.mapper.IUserMapper.deleteUser", 1L);
           //update
           User updateUser = new User(2L, "update");
           int updateResult = sqlSession.update("com.oceanbase.mapper.IUserMapper.updateUser", updateUser);
           //selectUsers
           List<User> userList = sqlSession.selectList("com.oceanbase.mapper.IUserMapper.selectUsers", null);
           userList.forEach(System.out::println);
           //System.out.println("userList = " + userList);
           statement.close();
           sqlSession.commit();
           sqlSession.close();
       }
   

4. Define the testAppMapper method.

   The testAppMapper method is used to test the functionality of AppMapper.

   1. Use the build() method of the SqlSessionFactoryBuilder class to create a SqlSessionFactory instance. This instance is used to manage the creation and destruction of SqlSession instances.
   2. Use the openSession() method of the SqlSessionFactory instance to create a SqlSession instance. This instance can execute various SQL statements, including queries, inserts, updates, and deletes.
   3. Use the getConnection() method of the SqlSession instance to obtain a Connection instance. This instance can execute various database operations.
   4. Use the createStatement() method of the Connection instance to create a Statement instance. Execute SQL statements in sequence.
   5. Use the execute() method of the Statement object to execute an SQL statement that deletes the test_app table.
   6. Use the execute() method of the Statement object to create the test_app table. This table contains two fields: one is id, of type number(20), which serves as the primary key; the other is name, of type varchar2(100).
   7. Use the getMapper() method of the SqlSession instance to obtain an instance of the IAppMapper interface. Define various database operation methods.
   8. Use a for loop to insert 10 records into the test_app table. In each iteration of the loop, create a new App object, use the insertApp() method of the Mapper interface to execute the insert operation, and store the result of the insert operation in the insertResult variable.
   9. Use the delete() method of the mapper object to execute the delete operation. Set the deletion condition by passing in the parameter 1L. Store the result of the delete operation in the deleteResult variable.
   10. Use the mapper object to execute a database update operation. Create an App object, call the update method, and pass in the SQL statement identifier and parameter object to complete the update operation.
   11. Create an App object named updateApp with id set to 2L and name set to "update".
   12. Call the updateApp method of the mapper object and pass in the updateApp object to execute the update operation.
   13. Call the commit method of the sqlSession object to commit the database transaction.
   14. Call the selectApps method of the mapper object to query all App objects. Use the forEach method to traverse the userList and output it to the console.
   15. Call the startPage method of the PageHelper object and pass in the page number and number of records per page to set the pagination parameters. Query all App objects and return a List object containing all App objects.
   16. Call the getList method of the PageInfo object to obtain the list of App objects after pagination. Use the System.out.println method to print the list of App objects after pagination.
   17. Close the SqlSession object using sqlSession.close() to release the related resources.

   Sample code:

       public void testAppMapper() throws SQLException, IOException {
           //mybatis annotation usecases
           SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
           SqlSession sqlSession = sqlSessionFactory.openSession();
           Statement statement = sqlSession.getConnection().createStatement();
           try {
               statement.execute("drop table test_app");
           } catch (SQLException ex) {
           } finally {
               statement.execute("create table test_app(id number(20) primary key,name varchar2(100))");
           }
   
           IAppMapper mapper = sqlSession.getMapper(IAppMapper.class);
   
           //insert
           for (int i = 1; i <= 10; i++) {
               App app = new App((long) i, "insert" + i);
               Integer insertResult = mapper.insertApp(app);
           }
   
           //delete
           Integer deleteResult = mapper.deleteApp(1L);
           //update
           App updateApp = new App(2L, "update");
           Integer updateResult = mapper.updateApp(updateApp);
           //commit
           sqlSession.commit();
   
           //selectApps
           List<App> appList = mapper.selectApps();
           appList.forEach(System.out::println);
   
           //selectbyPage
           //set page parameters
           PageHelper.startPage(2, 3);
           //selectApps
           List<App> appList1 = mapper.selectApps();
           //get pageList
           PageInfo pageInfo = new PageInfo(appList1);
           List<App> pageList = pageInfo.getList();
           System.out.println("pageList = " + pageList);
   
           sqlSession.close();
       }
   

Full code

    <?xml version="1.0" encoding="UTF-8"?>
    <project xmlns="http://maven.apache.org/POM/4.0.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
        <modelVersion>4.0.0</modelVersion>

        <groupId>com.oceanbase.example</groupId>
        <artifactId>java-oceanbase-mybatis</artifactId>
        <version>1.0-SNAPSHOT</version>
        <build>
            <plugins>
                <plugin>
                    <groupId>org.apache.maven.plugins</groupId>
                    <artifactId>maven-compiler-plugin</artifactId>
                    <configuration>
                        <source>8</source>
                        <target>8</target>
                    </configuration>
                </plugin>
            </plugins>
        </build>

        <dependencies>
            <dependency>
                <groupId>com.oceanbase</groupId>
                <artifactId>oceanbase-client</artifactId>
                <version>2.4.2</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.10</version>
            </dependency>
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.9</version>
            </dependency>
            <!--  pagehelper plug-in -->
            <dependency>
                <groupId>com.github.pagehelper</groupId>
                <artifactId>pagehelper</artifactId>
                <version>5.3.0</version>
            </dependency>
        </dependencies>
    </project>

jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:oceanbase://host:port/TEST?useServerPrepStmts=true&rewriteBatchedStatements=true
jdbc.username=user_name
jdbc.password=******

    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
      <properties resource="jdbc.properties"></properties>
      <settings>
          <setting name="cacheEnabled" value="true"/>
          <setting name="lazyLoadingEnabled" value="true"/>
          <setting name="aggressiveLazyLoading" value="true"/>
          <setting name="multipleResultSetsEnabled" value="true"/>
          <setting name="useColumnLabel" value="true"/>
          <setting name="useGeneratedKeys" value="true"/>
          <setting name="autoMappingBehavior" value="PARTIAL"/>
          <setting name="defaultExecutorType" value="SIMPLE"/>
          <setting name="mapUnderscoreToCamelCase" value="true"/>
          <setting name="localCacheScope" value="SESSION"/>
          <setting name="jdbcTypeForNull" value="NULL"/>
      </settings>
      <plugins>
          <plugin interceptor="com.github.pagehelper.PageInterceptor">

              <property name="helperDialect" value="oracle"/>

              <property name="offsetAsPageNum" value="true"/>
              <property name="rowBoundsWithCount" value="true"/>
              <property name="pageSizeZero" value="true"/>

              <property name="reasonable" value="false"/>

              <property name="params" value="pageNum=start;pageSize=limit;"/>
              <property name="supportMethodsArguments" value="true"/>
              <property name="returnPageInfo" value="check"/>
          </plugin>
      </plugins>
      <environments default="development">
          <environment id="development">
              <transactionManager type="JDBC"/>
              <dataSource type="POOLED">
                  <property name="driver" value="${jdbc.driver}"/>
                  <property name="url" value="${jdbc.url}"/>
                  <property name="username" value="${jdbc.username}"/>
                  <property name="password" value="${jdbc.password}"/>
              </dataSource>
          </environment>
      </environments>
      <mappers>
          <mapper resource="com/alipay/oceanbase/mapper/IUserMapper.xml"></mapper>
          <mapper class="com.oceanbase.mapper.IAppMapper"></mapper>
      </mappers>
    </configuration>

    <?xml version="1.0" encoding="UTF-8"?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.oceanbase.mapper.IUserMapper">
        <insert id="insertUser" parameterType="com.oceanbase.pojo.User">
            INSERT INTO test_user (id,name) VALUES (#{id},#{name})
        </insert>
        <delete id="deleteUser" parameterType="long">
            DELETE FROM test_user WHERE id = #{id}
        </delete>
        <update id="updateUser" parameterType="com.oceanbase.pojo.User">
            UPDATE test_user SET name = #{name} WHERE id = #{id}
        </update>
        <select id="selectUsers" resultType="com.oceanbase.pojo.User">
            SELECT id,name FROM test_user
        </select>
        <!--    There are two ways to paginate queries: 1. Use the pagehelper plugin; 2. Use SQL statements to paginate  -->
        <!-- SQL statement pagination: Oracle-compatible mode does not support the limit keyword, and instead uses the unique field 'rownum'-->
        <select id="selectUserByPage" resultType="com.oceanbase.pojo.User">
            select id,name from ( select row_.*, rownum rownum_ from ( select * from test_user ) row_ where rownum
            <![CDATA[ <= ]]>  #{pageNum} * #{pageSize} ) where rownum_ <![CDATA[ >]]>  ( #{pageNum}- 1) * #{pageSize}
        </select>
    </mapper>

package com.oceanbase.mapper;

import com.oceanbase.pojo.App;
import org.apache.ibatis.annotations.*;

import java.util.List;

//using annotations
public interface IAppMapper {
    @Insert("insert into test_app(id,name) values(#{id},#{name})")
    Integer insertApp(App app);

    @Delete("delete from test_app  where id =#{id}")
    Integer deleteApp(Long id);

    @Update("update test_app set name= #{name} where id = #{id}")
    Integer updateApp(App user);

    @Select("select * from test_app")
    @Results({
            @Result(id = true, column = "id", property = "id"),
            @Result(column = "name", property = "name")
    })
    List<App> selectApps();
}

package com.oceanbase.mapper;

import com.oceanbase.pojo.User;
import org.apache.ibatis.annotations.Param;

import java.util.List;

//using XML
public interface IUserMapper {

    Integer insertUser(User user);


    Integer deleteUser(Long id);

    Integer updateUser(User user);


    List<User> selectUsers();


    public List<User> selectUserByPage(@Param("user") User user, @Param("pageNum") Integer pageNum,
                                       @Param("pageSize") Integer pageSize);
}

package com.oceanbase.pojo;

public class App {
    private Long id;
    private String name;

    public App() {
    }

    public App(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "App{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

package com.oceanbase.pojo;

public class User {
    private Long id;
    private String name;

    public User() {
    }

    public User(Long id, String name) {
        this.id = id;
        this.name = name;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

import com.oceanbase.mapper.IAppMapper;
import com.oceanbase.mapper.IUserMapper;
import com.oceanbase.pojo.App;
import com.oceanbase.pojo.User;
import com.github.pagehelper.PageHelper;
import com.github.pagehelper.PageInfo;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Test;

import java.io.IOException;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.List;


public class TestMybatis {
    @Test
    public void testUserMapper() throws SQLException, IOException {
        //mybatis xml usecases
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Statement statement = sqlSession.getConnection().createStatement();
        try {
            statement.execute("drop table test_user");
        } catch (SQLException ex) {
        } finally {
            statement.execute("create table test_user(id number(20) primary key,name varchar2(100))");
        }
        IUserMapper mapper = sqlSession.getMapper(IUserMapper.class);
        //insert 10 users
        for (int i = 1; i <= 10; i++) {
            User user = new User((long) i, "insert");
            Integer insertResult = mapper.insertUser(user);
        }
        //delete id==1
        Integer deleteResult = mapper.deleteUser(1L);
        //update id==2L name=update
        User updateUser = new User(2L, "update");
        Integer updateResult = mapper.updateUser(updateUser);
        //selectUsers query all
        List<User> userList = mapper.selectUsers();
        userList.forEach(System.out::println);
        //selectUsersByPage: use the rownum keyword in SQL statements to manually perform pagination queries,
        // example: data on page 2 (3 items per page)
        User user = new User();
        user.setName("insert");
        List<User> usersByPage = mapper.selectUserByPage(user, 2, 3);
        System.out.println("usersByPage = " + usersByPage);
        statement.close();
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void testSqlSession() throws SQLException, IOException {
        //SqlSession usecases
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Statement statement = sqlSession.getConnection().createStatement();
        try {
            statement.execute("drop table test_user");
        } catch (SQLException ex) {
        } finally {
            statement.execute("create table test_user(id number(20) primary key,name varchar2(100))");
        }
        //insert
        for (int i = 1; i <= 10; i++) {
            User user = new User((long) i, "insert");
            //Integer insertResult = mapper.insertUser(user);
            int insertResult = sqlSession.insert("com.oceanbase.mapper.IUserMapper.insertUser", user);
        }
        //delete
        int deleteResult = sqlSession.delete("com.oceanbase.mapper.IUserMapper.deleteUser", 1L);
        //update
        User updateUser = new User(2L, "update");
        int updateResult = sqlSession.update("com.oceanbase.mapper.IUserMapper.updateUser", updateUser);
        //selectUsers
        List<User> userList = sqlSession.selectList("com.oceanbase.mapper.IUserMapper.selectUsers", null);
        userList.forEach(System.out::println);
        //System.out.println("userList = " + userList);
        statement.close();
        sqlSession.commit();
        sqlSession.close();
    }

    @Test
    public void testAppMapper() throws SQLException, IOException {
        //mybatis annotation usecases
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis-config.xml"));
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Statement statement = sqlSession.getConnection().createStatement();
        try {
            statement.execute("drop table test_app");
        } catch (SQLException ex) {
        } finally {
            statement.execute("create table test_app(id number(20) primary key,name varchar2(100))");
        }

        IAppMapper mapper = sqlSession.getMapper(IAppMapper.class);

        //insert
        for (int i = 1; i <= 10; i++) {
            App app = new App((long) i, "insert" + i);
            Integer insertResult = mapper.insertApp(app);
        }

        //delete
        Integer deleteResult = mapper.deleteApp(1L);
        //update
        App updateApp = new App(2L, "update");
        Integer updateResult = mapper.updateApp(updateApp);
        //commit
        sqlSession.commit();

        //selectApps
        List<App> appList = mapper.selectApps();
        appList.forEach(System.out::println);

        //selectbyPage
        //set page parameters
        PageHelper.startPage(2, 3);
        //selectApps
        List<App> appList1 = mapper.selectApps();
        //get pageList
        PageInfo pageInfo = new PageInfo(appList1);
        List<App> pageList = pageInfo.getList();
        System.out.println("pageList = " + pageList);

        sqlSession.close();
    }
}