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JDBC连接池C3P0

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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：

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<?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

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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