java-结合c3p0封装的db 事务 类

package com.itheima.utils;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

import javax.sql.DataSource;

import com.mchange.v2.c3p0.ComboPooledDataSource;

public class DataSourceUtils {
private static ComboPooledDataSource ds=new ComboPooledDataSource();
private static ThreadLocal<Connection> tl=new ThreadLocal<>();

/**
* 获取数据源
* @return 连接池
*/
public static DataSource getDataSource(){
return ds;
}

/**
* 从当前线程上获取连接
* @return 连接
* @throws SQLException
*/
public static Connection getConnection() throws SQLException{
Connection conn = tl.get();
if(conn==null){
//第一次获取 创建一个连接 和当前的线程绑定
conn=ds.getConnection();

//绑定
tl.set(conn);
}
return conn;
}

/**
* 释放资源
*
* @param conn
*            连接
* @param st
*            语句执行者
* @param rs
*            结果集
*/
public static void closeResource(Connection conn, Statement st, ResultSet rs) {
closeResource(st, rs);
closeConn(conn);
}

public static void closeResource(Statement st, ResultSet rs) {
closeResultSet(rs);
closeStatement(st);
}

/**
* 释放连接
*
* @param conn
*            连接
*/
public static void closeConn(Connection conn) {
if (conn != null) {
try {
conn.close();
//和当前的线程解绑
tl.remove();
} catch (SQLException e) {
e.printStackTrace();
}
conn = null;
}

}

/**
* 释放语句执行者
*
* @param st
*            语句执行者
*/
public static void closeStatement(Statement st) {
if (st != null) {
try {
st.close();
} catch (SQLException e) {
e.printStackTrace();
}
st = null;
}

}

/**
* 释放结果集
*
* @param rs
*            结果集
*/
public static void closeResultSet(ResultSet rs) {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
rs = null;
}

}

/**
* 开启事务
* @throws SQLException
*/
public static void startTransaction() throws SQLException{
//获取连接//开启事务
getConnection().setAutoCommit(false);
}

/**
* 事务提交
*/
public static void commitAndClose(){
try {
//获取连接
Connection conn = getConnection();
//提交事务
conn.commit();
//释放资源
conn.close();
//解除绑定
tl.remove();
} catch (SQLException e) {
e.printStackTrace();
}
}

/**
* 事务回滚
*/
public static void rollbackAndClose(){
try {
//获取连接
Connection conn = getConnection();
//事务回滚
conn.rollback();
//释放资源
conn.close();
//解除绑定
tl.remove();
} catch (SQLException e) {
e.printStackTrace();
}
}
}