C3P0数据库连接池的两种实现方式

https://www.bilibili.com/video/BV1eJ411c7rf?p=47

在 pom.xml 中加入依赖

<dependency>
    <groupId>c3p0</groupId>
    <artifactId>c3p0</artifactId>
    <version>0.9.1.2</version>
</dependency>

测试获取连接方式一：硬编码配置参数

参考 https://www.mchange.com/projects/c3p0/#quickstart

package io.github.jihch.connection;

import com.mchange.v2.c3p0.ComboPooledDataSource;
import org.junit.Test;

import java.beans.PropertyVetoException;
import java.sql.Connection;
import java.sql.SQLException;

public class C3P0Test {

    @Test
    public void testGetConnection() throws PropertyVetoException, SQLException {

        //获取 C3P0 数据库连接池
        ComboPooledDataSource cpds = new ComboPooledDataSource();
        cpds.setDriverClass( "com.mysql.cj.jdbc.Driver" ); //loads the jdbc driver
        cpds.setJdbcUrl( "jdbc:mysql://localhost:3306/jdbc_test?rewriteBatchedStatements=true" );
        cpds.setUser("root");
        cpds.setPassword("123456");

        //通过设置相关的参数，对数据库连接池进行管理：
        //设置初始时数据库连接池中的连接数
        cpds.setInitialPoolSize(10);

        Connection conn = cpds.getConnection();
        System.out.println(conn);

    }

}

一月 10, 2023 5:25:24 下午 com.mchange.v2.log.MLog <clinit>
信息: MLog clients using java 1.4+ standard logging.
一月 10, 2023 5:25:24 下午 com.mchange.v2.c3p0.C3P0Registry banner
信息: Initializing c3p0-0.9.1.2 [built 21-May-2007 15:04:56; debug? true; trace: 10]
一月 10, 2023 5:25:24 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource getPoolManager
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 3, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, dataSourceName -> 1hgeby9at1708kzd10rvblt|43556938, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.cj.jdbc.Driver, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hgeby9at1708kzd10rvblt|43556938, idleConnectionTestPeriod -> 0, initialPoolSize -> 10, jdbcUrl -> jdbc:mysql://localhost:3306/jdbc_test?rewriteBatchedStatements=true, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 15, maxStatements -> 0, maxStatementsPerConnection -> 0, minPoolSize -> 3, numHelperThreads -> 3, numThreadsAwaitingCheckoutDefaultUser -> 0, preferredTestQuery -> null, properties -> {user=******, password=******}, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false ]
com.mchange.v2.c3p0.impl.NewProxyConnection@668bc3d5

C3P0 数据库连接池的相关配置属性

https://www.mchange.com/projects/c3p0/#configuration_properties

测试获取连接方式二：c3p0-config.xml 配置文件

参考 https://www.mchange.com/projects/c3p0/#c3p0-config.xml

c3p0-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<c3p0-config>

    <named-config name="helloc3p0">

        <!-- 提供获取连接的4个基本信息 -->
        <property name="driverClass">com.mysql.cj.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/jdbc_test?rewriteBatchedStatements=true</property>
        <property name="user">root</property>
        <property name="password">123456</property>

        <!-- 进行数据库连接池管理的基本信息 -->
        <!-- 当数据库连接池中的连接数不够时，C3P0 一次性向数据库服务器申请的连接数 -->
        <property name="acquireIncrement">5</property>
        <!-- C3P0 数据库连接池初始化时的连接数 -->
        <property name="initialPoolSize">10</property>
        <!-- c3p0 数据库连接池中维护的最少连接数 -->
        <property name="minPoolSize">10</property>
        <!-- c3p0 数据库连接池维护的最多的连接数 -->
        <property name="maxPoolSize">100</property>

        <!-- c3p0 数据库连接池最多维护的 Statement 的个数 -->
        <property name="maxStatements">0</property>
        <!-- 每个连接中最多使用的 Statement 的个数 -->
        <property name="maxStatementsPerConnection">2</property>

    </named-config>

</c3p0-config>

    //方式二：使用配置文件
    @Test
    public void testGetConnection1() throws SQLException {
        ComboPooledDataSource cpds = new ComboPooledDataSource("helloc3p0");
        Connection conn = cpds.getConnection();
        System.out.println(conn);
    }

一月 10, 2023 5:55:36 下午 com.mchange.v2.log.MLog <clinit>
信息: MLog clients using java 1.4+ standard logging.
一月 10, 2023 5:55:37 下午 com.mchange.v2.c3p0.C3P0Registry banner
信息: Initializing c3p0-0.9.1.2 [built 21-May-2007 15:04:56; debug? true; trace: 10]
一月 10, 2023 5:55:37 下午 com.mchange.v2.c3p0.impl.AbstractPoolBackedDataSource getPoolManager
信息: Initializing c3p0 pool... com.mchange.v2.c3p0.ComboPooledDataSource [ acquireIncrement -> 5, acquireRetryAttempts -> 30, acquireRetryDelay -> 1000, autoCommitOnClose -> false, automaticTestTable -> null, breakAfterAcquireFailure -> false, checkoutTimeout -> 0, connectionCustomizerClassName -> null, connectionTesterClassName -> com.mchange.v2.c3p0.impl.DefaultConnectionTester, dataSourceName -> helloc3p0, debugUnreturnedConnectionStackTraces -> false, description -> null, driverClass -> com.mysql.cj.jdbc.Driver, factoryClassLocation -> null, forceIgnoreUnresolvedTransactions -> false, identityToken -> 1hgeby9at171bflx9hg39a|161cd475, idleConnectionTestPeriod -> 0, initialPoolSize -> 10, jdbcUrl -> jdbc:mysql://localhost:3306/jdbc_test?rewriteBatchedStatements=true, maxAdministrativeTaskTime -> 0, maxConnectionAge -> 0, maxIdleTime -> 0, maxIdleTimeExcessConnections -> 0, maxPoolSize -> 100, maxStatements -> 0, maxStatementsPerConnection -> 2, minPoolSize -> 10, numHelperThreads -> 3, numThreadsAwaitingCheckoutDefaultUser -> 0, preferredTestQuery -> null, properties -> {user=******, password=******}, propertyCycle -> 0, testConnectionOnCheckin -> false, testConnectionOnCheckout -> false, unreturnedConnectionTimeout -> 0, usesTraditionalReflectiveProxies -> false ]
com.mchange.v2.c3p0.impl.NewProxyConnection@64616ca2

https://github.com/jihch/jdbc_2/blob/main/src/main/resources/c3p0-config.xml

https://github.com/jihch/jdbc_2/blob/main/src/main/java/io/github/jihch/connection/C3P0Test.java