Connect to OceanBase Database by using a HikariCP connection pool

This topic introduces how to build an application by using a HikariCP connection pool, MySQL Connector/J, and OceanBase Database. It also covers the use of the application for fundamental database operations, including table creation, data insertion, data deletion, data updating, and data query.

Download the hikaricp-mysql-client sample project

Prerequisites

• You have installed OceanBase Database and created a MySQL tenant.

• You have installed Java Development Kit (JDK) 1.8 and Maven.

• You have installed Eclipse.

  Note

  The tool used to run the sample code in this topic is Eclipse IDE for Java Developers (2022-03), but you can also choose a tool that suits your personal preference to run the code.

Procedure

1. Import the hikaricp-mysql-client project into Eclipse.
2. Obtain the URL of OceanBase Database.
3. Modify the database connection information in the hikaricp-mysql-client project.
4. Run the hikaricp-mysql-client project.

Step 1: Import the hikaricp-mysql-client project into Eclipse

1. Start Eclipse and choose File > Open Projects from File System.

2. In the dialog box that appears, click Directory to browse and select the project, and then click Finish.

   Note

   When you import a Maven project using Eclipse, it will automatically detect the pom.xml file in the project, download the required dependency libraries based on the described dependencies in the file, and add them to the project.

   

3. View the project.

   

Step 2: Obtain the URL of OceanBase Database

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

   Here is an example:

   obclient -hxxx.xxx.xxx.xxx -P2881 -utest_user001@mysql001 -p****** -Dtest
   

   For more information about the connection string, see Connect to an OceanBase tenant by using OBClient.

2. Fill in the URL below based on the OceanBase Database connection string.

   jdbc:mysql://$host:$port/$database_name?user=$user_name&password=$password&useSSL=false
   

   where

   • $host specifies the IP address for connecting to OceanBase Database. For connection through OceanBase Database Proxy (ODP), this parameter is the IP address of an ODP. For direct connection, this parameter is the IP address of an OBServer node.

   • $port specifies the port for connecting to OceanBase Database. For connection through ODP, 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.

   • $database_name specifies the name of the database to be accessed.

     Notice

     The user used to connect to the tenant must have the CREATE, INSERT, DELETE, UPDATE, and SELECT privileges on the database. For more information about user privileges, see Privilege types in MySQL mode.

   • $user_name specifies the tenant account. For connection through ODP, the tenant account can be in the username@tenant name#cluster name or cluster name:tenant name:username format. For direct connection, the tenant account is in the username@tenant name format.

   • $password specifies the password of the account.

   For more information about the connection properties of MySQL Connector/J, see Configuration Properties.

   Here is an example:

   jdbc:mysql://xxx.xxx.xxx.xxx:2881/test?user=test_user001@mysql001&password=******&useSSL=false
   

Step 3: Modify the database connection information in the hikaricp-mysql-client project

Modify the database connection information in the hikaricp-mysql-client/src/main/resources/db.properties file based on the information obtained in Step 2.

Here is an example:

• The IP address of the OBServer node is xxx.xxx.xxx.xxx.
• The port is 2881.
• The name of the database to be accessed is test.
• The tenant account is test_user001@mysql001, where mysql001 is a MySQL user tenant created in OceanBase Database, and test_user001 is the username of the mysql001 tenant.
• The password is ******.

The sample code is as follows:

...
jdbcUrl=jdbc:mysql://xxx.xxx.xxx.xxx:2881/test?useSSL=false
username=test_user001@mysql001
password=******
...

Step 4: Run the hikaricp-mysql-client project

1. In the project navigation view, locate and expand the src/main/java directory.

2. Right-click the Main.java file and choose Run As > Java Application.

   

3. In the console window of Eclipse, view the project logs and output results.

   

4. You can also execute the following SQL statement in OceanBase Client (OBClient) to view the results:

   obclient [(none)]> SELECT * FROM test.test_hikaricp;
   

   The return result is as follows:

   +------+-------------+
   | id   | name        |
   +------+-------------+
   |    1 | test_update |
   +------+-------------+
   1 row in set
   

Project code introduction

Click hikaricp-mysql-client to download the project code, which is a compressed file named hikaricp-mysql-client.zip.

After decompressing it, you will find a folder named hikaricp-mysql-client. The directory structure is as follows:

hikaricp-mysql-client
├── src
│   └── main
│       ├── java
│       │   └── com
│       │       └── example
│       │           └── Main.java
│       └── resources
│           └── db.properties
└── pom.xml

Here is a breakdown of the files and directories:

• src: the root directory for storing the source code.
• main: the directory for storing the main code, including the major logic of the application.
• java: the directory for storing the Java source code.
• com: the directory for storing the Java package.
• example: the directory for storing the packages of the sample project.
• Main.java: a sample file of the main class that contains logic for table creation, data insertion, data deletion, data modification, and data query.
• resources: the directory for storing resource files, including configuration files.
• db.properties: the configuration file of the connection pool, which contains relevant database connection parameters.
• pom.xml: the configuration file of the Maven project, which is used to manage project dependencies and build settings.

Code in the pom.xml file

The pom.xml file is a configuration file for Maven projects, which defines the dependencies, plug-ins, and build rules of the projects. Maven is a Java project management tool that can automatically download dependencies, compile, and package the projects.

To configure the pom.xml file, perform the following steps:

1. Declare the file.

   Declare the file to be an XML file that uses XML standard 1.0 and character encoding UTF-8.

   The sample code is as follows:

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

2. Configure the namespaces and the POM model version.

   1. xmlns: the default XML namespace, which is set to http://maven.apache.org/POM/4.0.0.
   2. xmlns:xsi: the namespace for XML elements prefixed with xsi, which is set to http://www.w3.org/2001/XMLSchema-instance.
   3. xsi:schemaLocation: the mapping between the XML namespace and its corresponding XML schema definition (XSD) file. The value typically consists of paired strings separated by spaces. Each pair consists of a default XML namespace (http://maven.apache.org/POM/4.0.0) in the first part, and the URI of the corresponding XSD file (http://maven.apache.org/xsd/maven-4.0.0.xsd) in the second part.
   4. <modelVersion>: the POM model version used by the POM file, which is set to 4.0.0.

   The sample code is as follows:

   <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>
   
    <! -- Other configurations -->
   
   </project>
   

3. Configure basic information.

   1. <groupId>: the ID of the group to which the project belongs, which is set to com.example.
   2. <artifactId>: the name of the project, which is set to hikaricp-mysql-client.
   3. <version>: the project version, which is set to 1.0-SNAPSHOT.

   The sample code is as follows:

       <groupId>com.example</groupId>
       <artifactId>hikaricp-mysql-client</artifactId>
       <version>1.0-SNAPSHOT</version>
   

4. Configure the properties of the project's source file.

   Specify the Maven compiler plug-in as maven-compiler-plugin, and set both the source code and target Java versions to 8. This means that the project's source code is written using Java 8, and the compiled bytecode will also be compatible with the Java 8 runtime environment. This setup ensures that the project can correctly handle the syntax and features of Java 8 during compilation and runtime.

   Note

   Java 1.8 and Java 8 are different names for the same version.

   The sample code is as follows:

       <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. Configure the components on which the project depends.

   1. Add the mysql-connector-java dependency library for interactions with the database, and configure the following parameters:

      1. <groupId>: the ID of the group to which the dependency belongs, which is set to mysql.
      2. <artifactId>: the name of the dependency, which is set to mysql-connector-java.
      3. <version>: the version of the dependency, which is set to 5.1.40.

      The sample code is as follows:

              <dependency>
                  <groupId>mysql</groupId>
                  <artifactId>mysql-connector-java</artifactId>
                  <version>5.1.40</version>
              </dependency>
      

   2. Add the HikariCP dependency library for implementing a high-performance JDBC connection pool, and configure the following parameters:

      1. <groupId>: the ID of the group to which the dependency belongs, which is set to com.zaxxer.
      2. <artifactId>: the name of the dependency, which is set to HikariCP.
      3. <version>: the version of the dependency, which is set to 3.3.1.

      The sample code is as follows:

              <dependency>
                  <groupId>com.zaxxer</groupId>
                  <artifactId>HikariCP</artifactId>
                  <version>3.3.1</version>
              </dependency>
      

   3. Add the logback-classic dependency library for log recording and management, and configure the following parameters:

      1. <groupId>: the ID of the group to which the dependency belongs, which is set to ch.qos.logback.
      2. <artifactId>: the name of the dependency, which is set to logback-classic.
      3. <version>: the version of the dependency, which is set to 1.2.5.

      The sample code is as follows:

              <dependency>
                  <groupId>ch.qos.logback</groupId>
                  <artifactId>logback-classic</artifactId>
                  <version>1.2.5</version>
              </dependency>
      

Code in the db.properties file

db.properties is a sample configuration file of the connection pool. The configuration file contains the URL, username, and password for connecting to the database, and other optional parameters of the connection pool.

To configure the db.properties file, perform the following steps:

1. Configure database connection parameters.

   1. Specify the URL for connecting to the database, including the host IP address, port number, and database to be accessed.
   2. Specify the username for connecting to the database.
   3. Specify the password for connecting to the database.

   The sample code is as follows:

   jdbcUrl=jdbc:mysql://$host:$port/$database_name?useSSL=false
   username=$user_name
   password=$password
   

   where

   • $host specifies the IP address for connecting to OceanBase Database. For connection through OceanBase Database Proxy (ODP), this parameter is the IP address of an ODP. For direct connection, this parameter is the IP address of an OBServer node.
   • $port specifies the port for connecting to OceanBase Database. For connection through ODP, 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.
   • $database_name specifies the name of the database to be accessed.
   • $user_name specifies the tenant account. For connection through ODP, the tenant account can be in the username@tenant name#cluster name or cluster name:tenant name:username format. For direct connection, the tenant account is in the username@tenant name format.
   • $password specifies the password of the account.

2. Configure other connection pool parameters.

   1. Enable caching for precompiled SQL statements.
   2. Set the cache size for precompiled SQL statements to 250.
   3. Set the maximum lifetime of connections to 1,800,000 ms (30 minutes). Connections exceeding the specified lifetime are closed.
   4. Set the timeout value of idle connections to 600,000 ms (10 minutes). Connections that have been idle for the specified period of time are closed.
   5. Set the timeout value for requesting a connection to 30,000 ms (30s). If no connection is obtained when the specified timeout value expires, an exception is thrown.

   The sample code is as follows:

   dataSource.cachePrepStmts=true
   dataSource.prepStmtCacheSize=250
   dataSource.maxLifetime=1800000
   dataSource.idleTimeout=600000
   dataSource.connectionTimeout=30000
   

The following table describes the basic parameters of the HikariCP connection pool.

Code in the Main.java file

The Main.java file is a part of the sample application. It demonstrates the process of obtaining a database connection from the HikariCP connection pool, executing a series of database operations, such as table creation, data insertion, data deletion, data modification, and data query, and returning the query result.

To configure the Main.java file, perform the following steps:

1. Import the required classes and packages.

   1. Define the name of the Java package as com.example, where the package is used for organizing and managing Java classes.
   2. Import the java.sql.Connection class for establishing and managing connections with the database.
   3. Import the java.sql.PreparedStatement class for executing precompiled SQL statements.
   4. Import the java.sql.ResultSet class for processing query result sets.
   5. Import the java.sql.SQLException class for handling SQL exceptions.
   6. Import the HikariConfig class for configuring HikariCP connection pools.
   7. Import the HikariDataSource class for creating and managing HikariCP connection pools.

   The sample code is as follows:

   package com.example;
   
   import java.sql.Connection;
   import java.sql.PreparedStatement;
   import java.sql.ResultSet;
   import java.sql.SQLException;
   import com.zaxxer.hikari.HikariConfig;
   import com.zaxxer.hikari.HikariDataSource;
   

2. Define class names and methods.

   Define a Main class. The main method serves as the entry to the application. Call the main method to read the db.properties file to configure the HikariCP connection pool and request database connections. Then, call a series of methods in sequence to create a table, insert data, query data, update data, and delete data. If an SQLException occurs during the operation, the stack trace of the exception is recorded. The specific steps are as follows:

   1. Define a public class named Main.
   2. Define an entry method named main of the Main class.
   3. Create a HikariConfig object and configure the object based on the db.properties file.
   4. Create a HikariDataSource object and obtain a database connection by using the getConnection() method in the try-with-resources block.
   5. Call the table creation method and pass in the obtained database connection object to create a table named test_hikaricp.
   6. Call the data insertion method and pass in the obtained database connection object and data parameters to insert the (1,'A1') and (2,'A2') records.
   7. Call the data query method and pass in the obtained database connection object to query the inserted data.
   8. Call the data update method and pass in the obtained database connection object and update parameters to update the name column value of the row whose id value is 1 to test_update.
   9. Call the data query method and pass in the obtained database connection object to query the updated data.
   10. Call the data deletion method and pass in the obtained database connection object and deletion parameters to delete the row whose id value is 2.
   11. Call the data query method and pass in the obtained database connection object to query the data after the deletion.
   12. If an SQLException occurs in the try block, the stack trace of the exception is recorded.
   13. Define methods for creating tables, inserting data, querying data, updating data, and deleting data.

   The sample code is as follows:

   public class Main {
       public static void main(String[] args) {
           try {
               HikariConfig config = new HikariConfig("/db.properties");
               try (HikariDataSource dataSource = new HikariDataSource(config);
                   Connection conn = dataSource.getConnection()) {
                   createTable(conn);
   
                   insertData(conn, 1, "A1");
                   insertData(conn, 2, "A2");
   
                   selectData(conn);
   
                   updateData(conn, "test_update", 1);
                   selectData(conn);
   
                   deleteData(conn, 2);
                   selectData(conn);
               }
           } catch (SQLException e) {
               e.printStackTrace();
           }
       }
   
       // Define a method for creating tables.
       // Define a method for inserting data.
       // Define a method for querying data.
       // Define a method for updating data.
       // Define a method for deleting data.
   }
   

3. Define a method for creating tables.

   Define a private static method createTable for creating a table named test_hikaricp in the database. The table contains the id and name columns. The specific steps are as follows:

   1. Define a private static method createTable that receives a Connection object as a parameter, and declare that the method may throw an SQLException.
   2. Define an SQL statement string for creating a table named test_hikaricp. The table contains the id column (of the INT type) and name column (of the VARCHAR(50) type).
   3. Create a precompiled SQL statement object pstmt by using the Connection object conn and use the object in the try-with-resources block.
   4. Execute an SQL statement to create a table named test_hikaricp.
   5. If a success message is displayed in the console, the table is successfully created.

   The sample code is as follows:

       private static void createTable(Connection conn) throws SQLException {
           String sql = "CREATE TABLE IF NOT EXISTS test_hikaricp (id INT, name VARCHAR(50))";
           try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
               pstmt.executeUpdate();
               System.out.println("Table created successfully.");
           }
       }
   

4. Define a method for inserting data.

   Define a private static method insertData for inserting data into the test_hikaricp table in the database. The specific steps are as follows:

   1. Define a private static method insertData that receives a Connection object, an id parameter of the integer type, and a name parameter of the string type, and declare that the method may throw an SQLException.
   2. Define an SQL statement string for inserting the id and name columns into the test_hikaricp table.
   3. Create a precompiled SQL statement object pstmt by using the Connection object conn and use the object in the try-with-resources block.
   4. Set the value of the first parameter ? in the SQL statement to id.
   5. Set the value of the second parameter ? in the SQL statement to name.
   6. Execute the SQL statement to insert data into the table.
   7. If a success message is displayed in the console, the data is successfully inserted into the table.

   The sample code is as follows:

       private static void insertData(Connection conn, int id, String name) throws SQLException {
           String sql = "INSERT INTO test_hikaricp (id, name) VALUES (?, ?)";
           try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
               pstmt.setInt(1, id);
               pstmt.setString(2, name);
               pstmt.executeUpdate();
               System.out.println("Data inserted successfully.");
           }
       }
   

5. Define a method for querying data.

   Define a private static method selectData for querying data from the test_hikaricp table in the database. The specific steps are as follows:

   1. Define a private static method selectData that receives a Connection object as a parameter, and declare that the method may throw an SQLException.
   2. Define an SQL statement string for querying all data in the test_hikaricp table.
   3. Create a precompiled SQL statement object pstmt by using the Connection object conn and use the object in the try-with-resources block. Call the executeQuery() method to execute an SQL query and return the query result set object rs.
   4. If a message is displayed in the console, user data is being returned.
   5. Traverse the query result set. Call the next() method to check whether a next row exists in the result set. If yes, a loop begins.
   6. Obtain the value of the id column from the result set and assign it to the id variable.
   7. Obtain the value of the name column from the result set and assign it to the name variable.
   8. Return the id and name values of each row in the console.
   9. Return an empty row in the console.

   The sample code is as follows:

       private static void selectData(Connection conn) throws SQLException {
           String sql = "SELECT * FROM test_hikaricp";
           try (PreparedStatement pstmt = conn.prepareStatement(sql);
               ResultSet rs = pstmt.executeQuery()) {
               System.out.println("User Data:");
               while (rs.next()) {
                   int id = rs.getInt("id");
                   String name = rs.getString("name");
                   System.out.println("ID: " + id + ", Name: " + name);
               }
               System.out.println();
           }
       }
   

6. Define a method for updating data.

   Define a private static method updateData for updating data in the test_hikaricp table in the database. The specific steps are as follows:

   1. Define a private static method updateData that receives a Connection object, a name parameter of the string type, and an id parameter of the integer type, and declare that the method may throw an SQLException.
   2. Define an SQL statement string for updating the value of the name column in the row whose id column value equals the specified id value in the test_hikaricp table to the specified name value.
   3. Create a precompiled SQL statement object pstmt by using the Connection object conn and use the object in the try-with-resources block.
   4. Set the value of the first parameter ? in the SQL statement to name.
   5. Set the value of the second parameter ? in the SQL statement to id.
   6. Execute the SQL statement to update data in the table.
   7. If a success message is displayed in the console, the data is successfully updated.

   The sample code is as follows:

       private static void updateData(Connection conn, String name, int id) throws SQLException {
           String sql = "UPDATE test_hikaricp SET name = ? WHERE id = ?";
           try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
               pstmt.setString(1, name);
               pstmt.setInt(2, id);
               pstmt.executeUpdate();
               System.out.println("Data updated successfully.");
           }
       }
   

7. Define a method for deleting data.

   Define a private static method deleteData for deleting data that meets the specified condition from the test_hikaricp table in the database. The specific steps are as follows:

   1. Define a private static method deleteData that receives a Connection object and an id parameter of the integer type, and declare that the method may throw an SQLException.
   2. Define an SQL statement string for deleting data that meets the id = ? condition from the test_hikaricp table.
   3. Create a precompiled SQL statement object pstmt by using the Connection object conn and use the object in the try-with-resources block.
   4. Set the value of the first parameter ? in the SQL statement to id.
   5. Execute the SQL statement to delete data that meets the specified condition from the table.
   6. If a success message is displayed in the console, the data is successfully deleted.

   The sample code is as follows:

       private static void deleteData(Connection conn, int id) throws SQLException {
           String sql = "DELETE FROM test_hikaricp WHERE id = ?";
           try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
               pstmt.setInt(1, id);
               pstmt.executeUpdate();
               System.out.println("Data deleted successfully.");
           }
       }
   

Complete code examples

<?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</groupId>
    <artifactId>hikaricp-mysql-client</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>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.40</version>
        </dependency>
        <dependency>
            <groupId>com.zaxxer</groupId>
            <artifactId>HikariCP</artifactId>
            <version>3.3.1</version>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.5</version>
        </dependency>
    </dependencies>
</project>

jdbcUrl=jdbc:mysql://$host:$port/$database_name?useSSL=false
username=$user_name
password=$password

dataSource.cachePrepStmts=true
dataSource.prepStmtCacheSize=250
dataSource.maxLifetime=1800000
dataSource.idleTimeout=600000
dataSource.connectionTimeout=30000

package com.example;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;

public class Main {
    public static void main(String[] args) {
        try {
            HikariConfig config = new HikariConfig("/db.properties");
            try (HikariDataSource dataSource = new HikariDataSource(config);
                 Connection conn = dataSource.getConnection()) {
                createTable(conn);

                insertData(conn, 1, "A1");
                insertData(conn, 2, "A2");

                selectData(conn);

                updateData(conn, "test_update", 1);
                selectData(conn);

                deleteData(conn, 2);
                selectData(conn);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private static void createTable(Connection conn) throws SQLException {
        String sql = "CREATE TABLE IF NOT EXISTS test_hikaricp (id INT, name VARCHAR(50))";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.executeUpdate();
            System.out.println("Table created successfully.");
        }
    }

    private static void insertData(Connection conn, int id, String name) throws SQLException {
        String sql = "INSERT INTO test_hikaricp (id, name) VALUES (?, ?)";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setInt(1, id);
            pstmt.setString(2, name);
            pstmt.executeUpdate();
            System.out.println("Data inserted successfully.");
        }
    }

    private static void selectData(Connection conn) throws SQLException {
        String sql = "SELECT * FROM test_hikaricp";
        try (PreparedStatement pstmt = conn.prepareStatement(sql);
             ResultSet rs = pstmt.executeQuery()) {
            System.out.println("User Data:");
            while (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("name");
                System.out.println("ID: " + id + ", Name: " + name);
            }
            System.out.println();
        }
    }

    private static void updateData(Connection conn, String name, int id) throws SQLException {
        String sql = "UPDATE test_hikaricp SET name = ? WHERE id = ?";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setString(1, name);
            pstmt.setInt(2, id);
            pstmt.executeUpdate();
            System.out.println("Data updated successfully.");
        }
    }

    private static void deleteData(Connection conn, int id) throws SQLException {
        String sql = "DELETE FROM test_hikaricp WHERE id = ?";
        try (PreparedStatement pstmt = conn.prepareStatement(sql)) {
            pstmt.setInt(1, id);
            pstmt.executeUpdate();
            System.out.println("Data deleted successfully.");
        }
    }
}

References

• For more information about MySQL Connector/J, see Overview of MySQL Connector/J.
• For more information about the HikariCP connection pool, see HikariCP.