利用ThreadLocal管理事务

package com.itheima.util;
 
import java.sql.Connection;
import java.sql.SQLException;
//封装了所有与事务有关的方法
public class TransactionManager {
    private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();
    public static Connection getConnection(){
        Connection conn = tl.get();
        if(conn==null){//从当前线程中获取链接
            conn = DBCPUtil.getConnection();
            tl.set(conn);
        }
        return conn;
    }
    public static void startTransaction(){
        try {
            Connection conn = getConnection();
            conn.setAutoCommit(false);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public static void rollback(){
        try {
            Connection conn = getConnection();
            conn.rollback();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public static void commit(){
        try {
            Connection conn = getConnection();
            conn.commit();
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    public static void release(){
        try {
            Connection conn = getConnection();
            conn.close();
            tl.remove();//从当前线程中解绑。  与服务器实现有关：服务器采用线程池。
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}