格式和指针/十六进制值（内存覆盖）(Format and Pointers/Hex Values (Memory Overwrite))

 您应该使用Jdbc连接池。 然后从代码中需要连接到数据库的任何地方，只需从池中获取与数据库的连接（连接池将负责维护与数据库的所需连接数） 
 
 例如，如果您使用BoneCP： 
 
import com.jolbox.bonecp.BoneCP;
import com.jolbox.bonecp.BoneCPConfig;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;

/**
 * <dependency>
 * <groupId>com.jolbox</groupId>
 * <artifactId>bonecp</artifactId>
 * <version>0.8.0.RELEASE</version>
 * </dependency>
 */
public class BoneCPexample {

    public static final int TOTAL_CONNECTIONS_TO_DATABASE = 20;

    public static void main(String[] args) throws SQLException {
        BoneCPexample boneCPexample = new BoneCPexample();
        boneCPexample.doTheWork();
    }

    private void doTheWork() throws SQLException {


        String jdbcUrlString = "jdbc:postgresql://localhost/test_database";  // jdbc:postgresql://host:port/database
        BoneCPConfig bcpConfig = new BoneCPConfig();
        bcpConfig.setJdbcUrl(jdbcUrlString);
        bcpConfig.setUsername("postgres");
        bcpConfig.setPassword("mi-password");
        bcpConfig.setPartitionCount(1);
        bcpConfig.setMinConnectionsPerPartition(TOTAL_CONNECTIONS_TO_DATABASE);
        bcpConfig.setMaxConnectionsPerPartition(TOTAL_CONNECTIONS_TO_DATABASE);
        bcpConfig.setConnectionTimeoutInMs(1 * 1000);
        bcpConfig.setDefaultAutoCommit(false);
        bcpConfig.setConnectionTestStatement("select now()");
        bcpConfig.setIdleConnectionTestPeriodInMinutes(5);


        BoneCP boneCP = new BoneCP(bcpConfig);
        Connection connection = boneCP.getConnection();

        Statement statement = connection.createStatement();
        statement.execute("select * from mytable");

    }
}

you should use a Jdbc Connection Pool. then from anywhere in the code that you need a connection to the database, just get a connection to the database from the pool (the Connection Pool will be in charge of maintaining the desired number of connections to your database)
 
for example, if you use BoneCP:
 
import com.jolbox.bonecp.BoneCP;
import com.jolbox.bonecp.BoneCPConfig;

import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;

/**
 * <dependency>
 * <groupId>com.jolbox</groupId>
 * <artifactId>bonecp</artifactId>
 * <version>0.8.0.RELEASE</version>
 * </dependency>
 */
public class BoneCPexample {

    public static final int TOTAL_CONNECTIONS_TO_DATABASE = 20;

    public static void main(String[] args) throws SQLException {
        BoneCPexample boneCPexample = new BoneCPexample();
        boneCPexample.doTheWork();
    }

    private void doTheWork() throws SQLException {


        String jdbcUrlString = "jdbc:postgresql://localhost/test_database";  // jdbc:postgresql://host:port/database
        BoneCPConfig bcpConfig = new BoneCPConfig();
        bcpConfig.setJdbcUrl(jdbcUrlString);
        bcpConfig.setUsername("postgres");
        bcpConfig.setPassword("mi-password");
        bcpConfig.setPartitionCount(1);
        bcpConfig.setMinConnectionsPerPartition(TOTAL_CONNECTIONS_TO_DATABASE);
        bcpConfig.setMaxConnectionsPerPartition(TOTAL_CONNECTIONS_TO_DATABASE);
        bcpConfig.setConnectionTimeoutInMs(1 * 1000);
        bcpConfig.setDefaultAutoCommit(false);
        bcpConfig.setConnectionTestStatement("select now()");
        bcpConfig.setIdleConnectionTestPeriodInMinutes(5);


        BoneCP boneCP = new BoneCP(bcpConfig);
        Connection connection = boneCP.getConnection();

        Statement statement = connection.createStatement();
        statement.execute("select * from mytable");

    }
}