转账示例(一):Dao层面实现(本例采用QueryRunner来执行sql语句,数据源为C3P0)

缺点:Dao层面把Service层面的操作完成了,不利于后期的代码修改和重构

1.自行创建C3P0Util

account数据库

转账示例(一):Dao层面实现(本例采用QueryRunner来执行sql语句,数据源为C3P0)

2.jar包

转账示例(一):Dao层面实现(本例采用QueryRunner来执行sql语句,数据源为C3P0)

3.Dao层面

接口:

package com.learning.dao;

import com.learning.domain.Account;

public interface AccountDao {
/**
* 转账
* @param fromname 转出用户
* @param toname 转入用户
* @param money 转账金额
*/
public void updateAccount(String fromname,String toname,double money)throws Exception;
}

实现类:

package com.learning.dao.impl;

import java.sql.SQLException;

import org.apache.commons.dbutils.QueryRunner;

import com.learning.dao.AccountDao;
import com.learning.util.C3P0Util; public class AccountDaoImpl implements AccountDao { public void updateAccount(String fromname, String toname, double money) throws Exception {
//创建一个QueryRunner对象
QueryRunner qr = new QueryRunner(C3P0Util.getDataSource());
qr.update("update account set money=money-? where name=?",money,fromname);
qr.update("update account set money=money+? where name=?",money,toname);
} }
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