数据库连接池–C3P0连接池详解编程语言

c3p0是一个开源的jdbc连接池，hibernate 默认支持该数据源
jar文件:
c3p0-0.9.2-pre5.jar
mchange-commons-java-0.2.3.jar

基本示例：

package com.my.c3p0; 
 
import java.beans.PropertyVetoException; 
import java.sql.Connection; 
import java.sql.SQLException; 
 
import com.mchange.v2.c3p0.ComboPooledDataSource; 
 
public class C3p0Util { 
 
    private static ComboPooledDataSource dataSource; 
 
    static{ 
        try { 
            dataSource = new ComboPooledDataSource(); 
            // 基本4项 
            dataSource.setDriverClass("com.mysql.jdbc.Driver"); 
            dataSource.setJdbcUrl("jdbc:mysql://localhost:3306/mydb"); 
            dataSource.setUser("root"); 
            dataSource.setPassword("1234"); 
 
            // 其他项 
            // 最大连接数 
            dataSource.setMaxPoolSize(50); 
            // 最小连接数 
            dataSource.setMinPoolSize(10); 
            // 每次增长的个数 
            dataSource.setAcquireIncrement(5); 
        } catch (PropertyVetoException e) { 
            e.printStackTrace(); 
        } 
    } 
 
    public static Connection getConnection() throws SQLException{ 
        return dataSource.getConnection(); 
    } 
 
} 

基于XML配置文件的示例：

XML文件（c3p0-config.xml）：

<c3p0-config> 
    <!-- 默认配置，如果没有指定则使用这个配置 --> 
    <default-config> 
        <property name="checkoutTimeout">30000</property> 
        <property name="idleConnectionTestPeriod">30</property> 
        <property name="initialPoolSize">10</property> 
        <property name="maxIdleTime">30</property> 
        <property name="maxPoolSize">100</property> 
        <property name="minPoolSize">10</property> 
        <property name="maxStatements">200</property> 
        <user-overrides user="test-user"> 
            <property name="maxPoolSize">10</property> 
            <property name="minPoolSize">1</property> 
            <property name="maxStatements">0</property> 
        </user-overrides> 
    </default-config>  
    <!-- 命名的配置 --> 
    <named-config name="myDataSource"> 
        <property name="driverClass">com.mysql.jdbc.Driver</property> 
        <property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/mydb?useUnicode=true&amp;characterEncoding=UTF-8</property> 
        <property name="user">root</property> 
        <property name="password">1234</property> 
    <!-- 如果池中数据连接不够时一次增长多少个 --> 
        <property name="acquireIncrement">5</property> 
        <property name="initialPoolSize">20</property> 
        <property name="minPoolSize">10</property> 
        <property name="maxPoolSize">40</property> 
        <property name="maxStatements">0</property> 
        <property name="maxStatementsPerConnection">5</property> 
    </named-config> 
</c3p0-config>  

Java代码：

package com.my.c3p0; 
 
import java.sql.Connection; 
import java.sql.SQLException; 
 
import com.mchange.v2.c3p0.ComboPooledDataSource; 
 
public class C3p0Util2 { 
 
    private static ComboPooledDataSource dataSource; 
 
    static{ 
        dataSource = new ComboPooledDataSource("myDataSource");  //c3p0-config.xml <named-config name="myDataSource"> 配置名称 
    } 
 
    public static Connection getConnection() throws SQLException{ 
        return dataSource.getConnection(); 
    } 
 
}