JDBC连接池C3P0

介绍

  C3P0是一个开源的JDBC连接池,它实现了数据源和JNDI绑定,支持JDBC3规范和JDBC2的标准扩展。目前使用它的开源项目有Hibernate,Spring等

XML文件配置

  配置文件名称:c3p0-config.xml(固定)
  配置文件位置:src下(类路径)
  配置文件内容:命名配置

  c3p0-config.xml示例:

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

    <default-config>
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/java</property>
        <property name="user">root</property>
        <property name="password">root</property>
        <property name="initialPoolSize">5</property>
        <property name="maxPoolSize">20</property>
    </default-config>

    <named-config name="zidingyimingcheng">
        <property name="driverClass">com.mysql.jdbc.Driver</property>
        <property name="jdbcUrl">jdbc:mysql://localhost:3306/java</property>
        <property name="user">root</property>
        <property name="password">root</property>
    </named-config>


</c3p0-config>

comboPooledDataSource对象读取配置文件

  1. 获取comboPooledDataSource对象
    ComboPooledDataSource combo = new ComboPooledDataSource();   
    或者 ComboPooledDataSource combo = new ComboPooledDataSource(“zidingyimingcheng”);
  2. 获取连接
    Connection conn = combo.getConnection();
  3. 编写SQL
    String sql = “select * from user where id=?”;
  4. 获取到执行sql的对象
    PreparedStatement prep = conn.prepareStatement(sql);
  5. 为sql语句添加参数
    prep.setInt(1, 1);
  6. 执行sql语句
    ResultSet re = prep.executeQuery();

简单代码示例

package com.rexyan.c3p0;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

import org.junit.Test;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Test {
    @Test
    public void JDBC_POOL_C3P0(){
        try {
            //加载c3p0-config.xml配置文件,实例化可以加名称,不加名称则加载默认配置
            ComboPooledDataSource combo = new ComboPooledDataSource("zidingyimingcheng");
            //根据配置文件的信息,连接数据库
            Connection conn = combo.getConnection();
            //书写sql语句
            String sql = "select * from user where id=?";
            //获取到执行sql的对象
            PreparedStatement prep = conn.prepareStatement(sql);
            //为sql语句添加参数
            prep.setInt(1, 1);
            //执行sql语句
            ResultSet re = prep.executeQuery();
            System.out.println(re.next());

        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
}

进行封装