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();
        }
    }
}