JavaWeb学习-DBUtils框架-4-处理转账版本一（不合适）

曾经终败给现在 2022-01-22 10:05 241阅读 0赞

关于框架DBUtils，三个核心对象介绍，我们已经学习完了两个对象，还差一个DBUtils工具类，这个工具类是用来处理事务。前面我们在介绍事务的时候，我们通过转账来举例，现在我们还是用转账来学习。

1.动态web项目结构

![20190605215732862.png][]

2.相关代码

package com.anthony.dao;
    
    public interface AccountDao {
    	
    	public void updateAccount(String fromName, String toName, double money) throws Exception;
    
    }

package com.anthony.dao.impl;
    
    import org.apache.commons.dbutils.QueryRunner;
    
    import com.anthony.dao.AccountDao;
    import com.anthony.datasource.C3P0Utils;
    
    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(C3P0Utils.getDataSource());
    		//转出
    		qr.update("update account set money=money-? where name=?", money, fromName);
    		qr.update("update account set money=money+? where name=?", money, toName);
    		
    	}
    	
    }

package com.anthony.entity;
    
    public class Account {
    	
    	private int id;
    	private String name;
    	private double money;
    	
    	public int getId() {
    		return id;
    	}
    	public void setId(int id) {
    		this.id = id;
    	}
    	public String getName() {
    		return name;
    	}
    	public void setName(String name) {
    		this.name = name;
    	}
    	public double getMoney() {
    		return money;
    	}
    	public void setMoney(double money) {
    		this.money = money;
    	}
    	@Override
    	public String toString() {
    		return "[id=" + id + ", name=" + name + ", money=" + money + "]";
    	}
    	
    }

package com.anthony.service;
    
    public interface AccountService {
    	
    	/**
    	   * 转账
    	 * @param fromName
    	 * @param toName
    	 * @param money
    	 * @throws Exception
    	 */
    	public void transfer(String fromName, String toName, double money) throws Exception;
    
    
    }

package com.anthony.service.impl;
    
    import com.anthony.dao.AccountDao;
    import com.anthony.dao.impl.AccountDaoImpl;
    import com.anthony.service.AccountService;
    
    public class AccountServiceImpl implements AccountService {
    	
    	AccountDao ad = new AccountDaoImpl();
    	
    	public void transfer(String fromName, String toName, double money) throws Exception {
    		ad.updateAccount(fromName, toName, money);
    	}
    
    }

上面没有贴C3P0代码，请看前面文章的代码。下面这个测试类是用来模拟servlet

package com.anthony.test;
    
    import com.anthony.service.AccountService;
    import com.anthony.service.impl.AccountServiceImpl;
    
    public class TestTransfer {
    	public static void main(String[] args) throws Exception {
    		AccountService as = new AccountServiceImpl();
    		as.transfer("aaa", "bbb", 100);
    	}
    
    }

运行一下确实，aaa的账户减少100，bbb账户增加100.

3.问题

这中写法是有一个问题，那就是我们转账本来是一个业务，但是实际上这个业务在DAO层实现了，而我们没有在service层实现这个业务。

[20190605215732862.png]: /images/20220122/3010ec1bb7494d89809b91e28183334c.png