C3P0配置与使用

一、C3P0配置

1、使用xml方式（名称为c3p0-config.xml）

<?xml version="1.0" encoding="UTF-8"?>
<c3p0-config>
	<default-config>
		<property name="jdbcUrl">jdbc:mysql://localhost:3306/tv_guide
		</property>
		<property name="driverClass">com.mysql.jdbc.Driver</property>
		<property name="user">root</property>
		<property name="password">root</property>

		<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>
	</default-config>
</c3p0-config>

2、使用properties方式（名称为c3p0.properties）

c3p0.jdbcUrl=jdbc:mysql://localhost:3306/tv_guide
c3p0.driverClass=com.mysql.jdbc.Driver
c3p0.user=root
c3p0.password=root

c3p0.acquireIncrement=3	
c3p0.idleConnectionTestPeriod=60	
c3p0.initialPoolSize=10	
c3p0.maxIdleTime=60	
c3p0.maxPoolSize=20	
c3p0.maxStatements=100	
c3p0.minPoolSize=5	

使用这两种方式进行配置时，只要将配置好的文件放入classpath文件夹下即可，在java代码当中不用显示的给出访问配置方式的代码，c3p0会自动识别！

二、C3P0的使用

import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class C3P0Utils {
	private static DataSource ds;

	private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>(); // map
	static {
		ds = new ComboPooledDataSource();//直接使用即可，不用显示的配置，其会自动识别配置文件
	}

	public static DataSource getDataSource() {
		return ds;
	}

	public static Connection getConnection() throws SQLException {
		try {
			// 得到当前线程上绑定的连接
			Connection conn = tl.get();
			if (conn == null) { // 代表线程上没有绑定连接
				conn = ds.getConnection();
				tl.set(conn);
			}
			return conn;
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	public static void startTransaction() {
		try {
			// 得到当前线程上绑定连接开启事务
			Connection conn = tl.get();
			if (conn == null) { // 代表线程上没有绑定连接
				conn = ds.getConnection();
				tl.set(conn);
			}
			conn.setAutoCommit(false);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	public static void commitTransaction() {
		try {
			Connection conn = tl.get();
			if (conn != null) {
				conn.commit();
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	public static void closeConnection() {
		try {
			Connection conn = tl.get();
			if (conn != null) {
				conn.close();
			}
		} catch (Exception e) {
			throw new RuntimeException(e);
		} finally {
			tl.remove(); // 千万注意，解除当前线程上绑定的链接（从threadlocal容器中移除对应当前线程的链接）
		}
	}

}

详细信息见：http://www.mchange.com/projects/c3p0/c3p0官方网站