对事务的支持

来源：互联网发布：关于知乎的诗词编辑：程序博客网时间：2024/05/17 06:21

使用c3p0连接池，编写工具类，实现对事务的支持

import java.sql.Connection;import java.sql.SQLException;import javax.sql.DataSource;import com.mchange.v2.c3p0.ComboPooledDataSource;public class JdbcUtils {private static ComboPooledDataSource dataSource = new ComboPooledDataSource();//事务专用链接private static ThreadLocal<Connection> tl = new ThreadLocal<Connection>();//使用连接池返回一个对象public static Connection getConnection() throws SQLException{Connection con = tl.get();if(con!=null) return con;return dataSource.getConnection();}//返回连接池对象public static DataSource getDataSource(){return dataSource;}//开启事务，并这是为手动提交public static void beginTransaction() throws SQLException{Connection con = tl.get();if(con!=null) throw new SQLException("已经开启了事务");con= getConnection();con.setAutoCommit(false);//设置为手动提交tl.set(con);//把当前线程的链接保存起来}//提交事务public static void rollbackTransation() throws SQLException{Connection con = tl.get();if(con == null)  throw new SQLException("还未开启事务，不能提交");con.commit();con.close();tl.remove();}//回滚事务public static void rollbackTransaction() throws SQLException {Connection con = tl.get();if(con==null) throw new SQLException("还未开启事务，不能回滚");con.rollback();con.close();tl.remove();}//释放连接public static void releaseConnection(Connection connection) throws SQLException {Connection con =tl.get();//如果是事务专用就不关闭//如果不是则关闭if(con == null) connection.close();if(con !=connection) connection.close();}}

重写QueryRunner不需要传递con的方法

import java.sql.Connection;import java.sql.SQLException;import org.apache.commons.dbutils.QueryRunner;import org.apache.commons.dbutils.ResultSetHandler;public class TxQueryRunner extends QueryRunner {@Overridepublic int[] batch(String sql, Object[][] params) throws SQLException {/* * 1.得到连接 * 2.执行父类方法，传递连接对象 * 3.释放连接 * 4.返回值 */Connection con = JdbcUtils.getConnection();int[] result = super.batch(con, sql, params);JdbcUtils.releaseConnection(con);return result;}@Overridepublic <T> T query(String sql, ResultSetHandler<T> rsh, Object... params)throws SQLException {// TODO Auto-generated method stubConnection con = JdbcUtils.getConnection();T result =  super.query(con,sql, rsh, params);JdbcUtils.releaseConnection(con);return result;}@Overridepublic <T> T query(String sql, ResultSetHandler<T> rsh) throws SQLException {// TODO Auto-generated method stubConnection con = JdbcUtils.getConnection();T result = super.query(con,sql, rsh);JdbcUtils.releaseConnection(con);return result;}@Overridepublic int update(String sql) throws SQLException {// TODO Auto-generated method stubConnection con = JdbcUtils.getConnection();int result = super.update(con,sql);JdbcUtils.releaseConnection(con);return result;}@Overridepublic int update(String sql, Object param) throws SQLException {// TODO Auto-generated method stubConnection con = JdbcUtils.getConnection();int result = super.update(con,sql, param);JdbcUtils.releaseConnection(con);return result;}@Overridepublic int update(String sql, Object... params) throws SQLException {// TODO Auto-generated method stubConnection con = JdbcUtils.getConnection();int  result = super.update(con,sql, params);JdbcUtils.releaseConnection(con);return result;}}

Dao中只需提供查询语句

public static void update(String name, double money) throws SQLException {QueryRunner qr = new TxQueryRunner();String sql = "update account set balance=balance+? where name=?";Object[] params = {money, name};qr.update(sql, params);}

在Sevice中只需开启事务，调用Dao，关闭事务即可

public void serviceMethod() throws Exception {try {JdbcUtils.beginTransaction();dao.update(...);dao.update(...);JdbcUtils.commitTransaction();} catch (Exception e) {try {JdbcUtils.rollbackTransaction();} catch (SQLException e1) {}throw e;}}

0 0