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
2.jar包
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);
} }