#题目 1（12分） 根据本单介绍的Spring JDBC，事务管理，MyBatis等内容，分别使用Spring JDBC及MyBatis提供一个转帐服务（保证事务），提供一个transferMoney接口：

transferMoney(Long srcUserId, Long targetUserId, double count)；// srcUserId及targetUserId为转帐用户标识

转帐涉及到的表（UserBalance）包含如下列：

#答案 ##初始化表结构 首先，根据表与表结构，创建表格与初始化数据内容

DROP TABLE IF EXISTS `UserBalance`;CREATE TABLE `UserBalance` (  `userId` int(11) NOT NULL AUTO_INCREMENT,  `balance` double DEFAULT NULL,  PRIMARY KEY (`userId`)) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;-- ------------------------------ Records of UserBalance-- ----------------------------INSERT INTO `UserBalance` VALUES ('1', '1000');INSERT INTO `UserBalance` VALUES ('2', '1000');

##定义Entity

package com.hava.homework.entity;/** * Created by yanfa on 2016/10/27. */public class UserBalance {    Long userId;    Double balance;    //Getter and Setter    public Long getUserId() {        return userId;    }    public void setUserId(Long userId) {        this.userId = userId;    }    public Double getBalance() {        return balance;    }    public void setBalance(Double balance) {        this.balance = balance;    }}

##定义UserBalanceDao接口

package com.hava.homework.repository;import com.hava.homework.entity.UserBalance;import java.util.List;/** * Created by yanfa on 2016/10/27. */public interface UserBalanceDaoInterface {    public List
    
      findAll();    public void addMoney(Long userId,double count);    public void subMoney(Long userId,double count);}
    

##分别实现 ###JdbcTemplate实现

package com.hava.homework.repository;import com.hava.homework.entity.UserBalance;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.jdbc.core.BeanPropertyRowMapper;import org.springframework.jdbc.core.JdbcTemplate;import org.springframework.stereotype.Repository;import javax.sql.DataSource;import java.util.List;/** * Created by yanfa on 2016/10/27. */@Repositorypublic class UserBalanceJdbcTemplateDao implements UserBalanceDaoInterface {    private JdbcTemplate jdbcTemplate;    @Autowired    public void setDataSource(DataSource dataSource) {        this.jdbcTemplate = new JdbcTemplate(dataSource);    }    @Override    public List
    
      findAll() {        return this.jdbcTemplate.query("SELECT * FROM UserBalance",new BeanPropertyRowMapper(UserBalance.class));    }    public void addMoney(Long userId, double count){        this.jdbcTemplate.update("UPDATE UserBalance SET balance=balance+? WHERE userId=?",count,userId);    }    public void subMoney(Long userId,double count){        this.jdbcTemplate.update("UPDATE UserBalance SET balance=balance-? WHERE userId=?",count,userId);    }    // srcUserId及targetUserId为转帐用户标识    public void transferMoney(Long srcUserId, Long targetUserId, double count){        System.out.println("transferMoney");        this.subMoney(srcUserId,count);        throwException();        this.addMoney(targetUserId,count);    }    private void throwException() {        throw new RuntimeException("Throw Exception");    }}
    

###MyBatis实现

package com.hava.homework.repository;import com.hava.homework.entity.UserBalance;import org.apache.ibatis.annotations.Select;import org.apache.ibatis.annotations.Update;import java.util.List;/** * Created by yanfa on 2016/10/27. */public interface UserBalanceMyBatisDao extends UserBalanceDaoInterface{    @Update("UPDATE UserBalance SET balance=balance+#{param2} WHERE userId=#{param1} ")    public void addMoney(Long userId,double count);    @Update("UPDATE UserBalance SET balance=balance-#{param2} WHERE userId=#{param1} ")    public void subMoney(Long userId,double count);    @Select("SELECT * FROM UserBalance")    public List
    
      findAll();}
    

##Service实现transferMoney 在TransferBalanceService实现transferMoney方法，并添加transaction

package com.hava.homework.service;import com.hava.homework.entity.UserBalance;import com.hava.homework.repository.UserBalanceDaoInterface;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service;import org.springframework.transaction.annotation.Transactional;import java.util.List;/** * Created by yanfa on 2016/10/27. */@Servicepublic class TransferBalanceService {    UserBalanceDaoInterface userBalanceDao;    public void setUserBalanceDao(UserBalanceDaoInterface userBalanceDao) {        this.userBalanceDao = userBalanceDao;    }    public List
    
      findAll(){        return this.userBalanceDao.findAll();    }    // srcUserId及targetUserId为转帐用户标识    @Transactional    public void transferMoney(Long srcUserId, Long targetUserId, double count){        System.out.println("Class TransferBalanceService Method transferMoney");        this.userBalanceDao.subMoney(srcUserId,count);        throwException();        this.userBalanceDao.addMoney(targetUserId,count);    }    private void throwException() {        throw new RuntimeException("Throw Exception");    }}
    

##Spring配置文件

##运行主类

package com.hava.homework;import com.hava.homework.entity.UserBalance;import com.hava.homework.repository.UserBalanceJdbcTemplateDao;import com.hava.homework.repository.UserBalanceMyBatisDao;import com.hava.homework.service.TransferBalanceService;import org.springframework.context.ApplicationContext;import org.springframework.context.ConfigurableApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;/** * Created by yanfa on 2016/10/27. */public class UserBalanceMain {    public static void main(String [] args){        ApplicationContext context = new ClassPathXmlApplicationContext("homework-context.xml");        // get dao bean        UserBalanceJdbcTemplateDao userBalanceJdbcTemplateDao = context.getBean("userBalanceJdbcTemplateDao",UserBalanceJdbcTemplateDao.class);        UserBalanceMyBatisDao userBalanceMyBatisDao = context.getBean("userBalanceMyBatisDao",UserBalanceMyBatisDao.class);        // get service        TransferBalanceService transferBalanceService = context.getBean("transferBalanceService",TransferBalanceService.class);        System.out.println("transferBalanceService.setUserBalanceDao is userBalanceJdbcTemplateDao");        transferBalanceService.setUserBalanceDao(userBalanceJdbcTemplateDao);        for(UserBalance userBalance : transferBalanceService.findAll())            System.out.println("userBalance[id]:" +userBalance.getUserId() + " [balance]:" + userBalance.getBalance());        try {            transferBalanceService.transferMoney(1l, 2l, 100l);        }catch(Exception e)        {            System.out.println(e.toString());        }        for(UserBalance userBalance : transferBalanceService.findAll())            System.out.println("userBalance[id]:" +userBalance.getUserId() + " [balance]:" + userBalance.getBalance());        System.out.println("transferBalanceService.setUserBalanceDao is userBalanceMyBatisDao");        transferBalanceService.setUserBalanceDao(userBalanceMyBatisDao);        for(UserBalance userBalance : transferBalanceService.findAll())            System.out.println("userBalance[id]:" +userBalance.getUserId() + " [balance]:" + userBalance.getBalance());        try {            transferBalanceService.transferMoney(2l,1l,100l);        }catch(Exception e)        {            System.out.println(e.toString());        }        for(UserBalance userBalance : transferBalanceService.findAll())            System.out.println("userBalance[id]:" +userBalance.getUserId() + " [balance]:" + userBalance.getBalance());        ((ConfigurableApplicationContext) context).close();    }}

##运行结果

transferBalanceService.setUserBalanceDao is userBalanceJdbcTemplateDaouserBalance[id]:1 [balance]:900.0userBalance[id]:2 [balance]:900.0Class TransferBalanceService Method transferMoneyjava.lang.RuntimeException: Throw ExceptionuserBalance[id]:1 [balance]:900.0userBalance[id]:2 [balance]:900.0transferBalanceService.setUserBalanceDao is userBalanceMyBatisDaouserBalance[id]:1 [balance]:900.0userBalance[id]:2 [balance]:900.0Class TransferBalanceService Method transferMoney

##IDE中运行图片