数据库连接池C3P0的使用

一、直接使用代码链接（一般企业开发不会用到。大多数用方法二）

1.导入jar

2.新建JDBCUtil

import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JDBCUtil {

	static String driverClass = null;
	static String url = null;
	static String name = null;
	static String password= null;

	static{
		try {
			//1. 创建一个属性配置对象
			Properties properties = new Properties();
			InputStream is = new FileInputStream("jdbc.properties");

			//导入输入流。
			properties.load(is);

			//读取属性
			driverClass = properties.getProperty("driverClass");
			url = properties.getProperty("url");
			name = properties.getProperty("name");
			password = properties.getProperty("password");

		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	/**
	 * 获取连接对象
	 * @return
	 */
	public static Connection getConn(){
		Connection conn = null;
		try {
			Class.forName(driverClass);
			//2. 建立连接 参数一： 协议 + 访问的数据库 ， 参数二： 用户名 ， 参数三： 密码。
			conn = DriverManager.getConnection(url, name, password);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return conn;
	}

	/**
	 * 释放资源
	 * @param conn
	 * @param st
	 * @param rs
	 */
	public static void release(Connection conn , Statement st , ResultSet rs){
		closeRs(rs);
		closeSt(st);
		closeConn(conn);
	}
	public static void release(Connection conn , Statement st){
		closeSt(st);
		closeConn(conn);
	}

	private static void closeRs(ResultSet rs){
		try {
			if(rs != null){
				rs.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			rs = null;
		}
	}

	private static void closeSt(Statement st){
		try {
			if(st != null){
				st.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			st = null;
		}
	}

	private static void closeConn(Connection conn){
		try {
			if(conn != null){
				conn.close();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			conn = null;
		}
	}
}

3.新建C3P0Demo

import java.sql.Connection;
import java.sql.PreparedStatement;
import org.junit.Test;
import com.hbxy.rick.util.JDBCUtil;
import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Demo {
	@Test
	public void testC3P0() {
		Connection conn = null;
		PreparedStatement ps = null;
		try {
			//1. 创建datasource
			ComboPooledDataSource dataSource = new ComboPooledDataSource();
			//2. 设置连接数据的信息
			dataSource.setDriverClass("com.mysql.jdbc.Driver");
			dataSource.setJdbcUrl("jdbc:mysql://localhost/eclipsetest");
			dataSource.setUser("root");
			dataSource.setPassword("xxxxxx");

			//2. 得到连接对象
			conn = dataSource.getConnection();
			String sql = "insert into stus values( ? , ?)";
			ps = conn.prepareStatement(sql);
			ps.setString(1, "admi234n");
			ps.setInt(2, 103200);

			ps.executeUpdate();

		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JDBCUtil.release(conn, ps);
		}

	}

}

二、用配置文件链接（重点）

1.导入jar

2.新建JDBCUtil

3.新建c3p0-config.xml配置文件（放在src目录下）

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

	<!-- default-config 默认的配置，  -->
  <default-config>
    <property name="driverClass">com.mysql.jdbc.Driver</property>
    <property name="jdbcUrl">jdbc:mysql://localhost/mydb</property>
    <property name="user">root</property>
    <property name="password">xxxxxx</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>
  </default-config>

   <!-- This app is massive! -->
  <named-config name="oracle">
    <property name="acquireIncrement">50</property>
    <property name="initialPoolSize">100</property>
    <property name="minPoolSize">50</property>
    <property name="maxPoolSize">1000</property>

    <!-- intergalactoApp adopts a different approach to configuring statement caching -->
    <property name="maxStatements">0</property>
    <property name="maxStatementsPerConnection">5</property>

    <!-- he's important, but there's only one of him -->
    <user-overrides user="master-of-the-universe">
      <property name="acquireIncrement">1</property>
      <property name="initialPoolSize">1</property>
      <property name="minPoolSize">1</property>
      <property name="maxPoolSize">5</property>
      <property name="maxStatementsPerConnection">50</property>
    </user-overrides>
  </named-config>

</c3p0-config>
	

4.新建C3P0Demo02

package com.hbxy.rick.c3p0;

import java.sql.Connection;
import java.sql.PreparedStatement;
import org.junit.Test;
import com.hbxy.rick.util.JDBCUtil;
import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Demo02 {

	@Test
	public void testC3P0() {
		Connection conn = null;
		PreparedStatement ps = null;
		try {
			//1. 创建datasource
			ComboPooledDataSource dataSource = new ComboPooledDataSource();

			//2. 得到连接对象
			conn = dataSource.getConnection();
			String sql = "insert into stus values( ? , ?)";
			ps = conn.prepareStatement(sql);
			ps.setString(1, "zhnsdgndngandgna ");
			ps.setInt(2, 3200);

			ps.executeUpdate();

		} catch (Exception e) {
			e.printStackTrace();
		}finally {
			JDBCUtil.release(conn, ps);
		}
	}
}