Mybatis实现银行转账业务的实现和ThreadLocal的机制解析-----Mybatis框架

今天药忘吃喽~ 2024-03-05 02:41 69阅读 0赞

>     package com.powernode.bank.web;
>     
>     import com.powernode.bank.exceptions.MoneyNotEnoughException;
>     import com.powernode.bank.exceptions.TransferException;
>     import com.powernode.bank.service.AccountService;
>     import com.powernode.bank.service.Impl.AccountServiceImpl;
>     
>     import javax.servlet.ServletException;
>     import javax.servlet.annotation.WebServlet;
>     import javax.servlet.http.HttpServlet;
>     import javax.servlet.http.HttpServletRequest;
>     import javax.servlet.http.HttpServletResponse;
>     import java.io.IOException;
>     
>     @WebServlet("/transfer")
>     public class AccountServlet extends HttpServlet
>     {
>         //为了让这个对象在其他方法中也可以使用,我们声明为实例变量
>         private AccountService accountService = new AccountServiceImpl();
>         @Override
>         protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
>         {
>             super.doGet(req, resp);
>             this.doPost(req,resp);
>         }
>     
>         @Override
>         protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             //获取表单数据
>             String fromActno = request.getParameter("fromActno");
>             String toActno = request.getParameter("toActno");
>             Double money = Double.parseDouble(request.getParameter("money"));
>             try
>             {
>                 //调用Service的转账方法完成转账(调业务层)
>                 accountService.transfer(fromActno,toActno,money);
>                 //程序走到这里就完成了转账
>                 response.sendRedirect(request.getContextPath() + "/Success.html");
>                 //调用视图层
>             }
>             catch (MoneyNotEnoughException e)
>             {
>                 //调用视图层
>                 response.sendRedirect(request.getContextPath() + "/error1.html");
>             }
>             catch (TransferException e)
>             {
>                 //调用视图层
>                 response.sendRedirect(request.getContextPath() + "/Error2.html");
>             }
>             catch(Exception e)
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error2.html");
>             }
>         }
>     }
> 
>     package com.powernode.bank.web;
>     
>     import com.powernode.bank.exceptions.MoneyNotEnoughException;
>     import com.powernode.bank.exceptions.TransferException;
>     import com.powernode.bank.service.AccountService;
>     import com.powernode.bank.service.Impl.AccountServiceImpl;
>     
>     import javax.servlet.ServletException;
>     import javax.servlet.annotation.WebServlet;
>     import javax.servlet.http.HttpServlet;
>     import javax.servlet.http.HttpServletRequest;
>     import javax.servlet.http.HttpServletResponse;
>     import java.io.IOException;
>     
>     @WebServlet("/transfer")
>     public class AccountServlet extends HttpServlet
>     {
>         //为了让这个对象在其他方法中也可以使用,我们声明为实例变量
>         private AccountService accountService = new AccountServiceImpl();
>         @Override
>         protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
>         {
>             super.doGet(req, resp);
>             this.doPost(req,resp);
>         }
>     
>         @Override
>         protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             //获取表单数据
>             String fromActno = request.getParameter("fromActno");
>             String toActno = request.getParameter("toActno");
>             Double money = Double.parseDouble(request.getParameter("money"));
>             try
>             {
>                 //调用Service的转账方法完成转账(调业务层)
>                 accountService.transfer(fromActno,toActno,money);
>                 //程序走到这里就完成了转账
>                 response.sendRedirect(request.getContextPath() + "/Success.html");
>                 //调用视图层
>             }
>             catch (MoneyNotEnoughException e)
>             {
>                 //调用视图层
>                 response.sendRedirect(request.getContextPath() + "/error1.html");
>             }
>             catch (TransferException e)
>             {
>                 //调用视图层
>                 response.sendRedirect(request.getContextPath() + "/Error2.html");
>             }
>             catch(Exception e)
>             {
>                 response.sendRedirect(request.getContextPath() + "/Error2.html");
>             }
>         }
>     }

>     package com.powernode.bank.utils;
>     
>     import org.apache.ibatis.io.Resources;
>     import org.apache.ibatis.session.SqlSession;
>     import org.apache.ibatis.session.SqlSessionFactory;
>     import org.apache.ibatis.session.SqlSessionFactoryBuilder;
>     
>     import java.io.IOException;
>     
>     public class SqlSessionUtil
>     {
>         private SqlSessionUtil(){}
>         private static SqlSessionFactory sqlSessionFactory;
>         static
>         {
>             try
>             {
>                 sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader("mybatis-config.xml"));
>             }
>             catch (IOException e)
>             {
>                 throw new RuntimeException(e);
>             }
>         }
>         //全局的服务器级别的,一个服务器一个即可的
>         private static ThreadLocal<SqlSession> local = new ThreadLocal<>();
>         public static SqlSession openSession()
>         {
>             SqlSession sqlSession = local.get();
>             if(sqlSession == null)
>             {
>                 sqlSession = sqlSessionFactory.openSession();
>                 local.set(sqlSession);
>             }
>             return sqlSession;
>         }
>         public static void close(SqlSession sqlSession)
>         {
>             //关闭SqlSession对象
>             if (sqlSession != null)
>             {
>                 sqlSession.close();
>                 //从当前线程中移除SqlSession对象
>                 //注意一定要一处当前线程和SqlSession对象的绑定关系
>                 //因为Tomcat服务器支持线程池,也就是说用过的线程有概率还会使用这个线程
>                 //如果我们关闭了该SqlSession然后没有移除,就会导致另外的用户有概率拿到这个空的SqlSession对象(已经被关闭了)
>                 local.remove();
>             }
>         }
>     }
> 
>     package com.powernode.bank.utils;
>     
>     import org.apache.ibatis.io.Resources;
>     import org.apache.ibatis.session.SqlSession;
>     import org.apache.ibatis.session.SqlSessionFactory;
>     import org.apache.ibatis.session.SqlSessionFactoryBuilder;
>     
>     import java.io.IOException;
>     
>     public class SqlSessionUtil
>     {
>         private SqlSessionUtil(){}
>         private static SqlSessionFactory sqlSessionFactory;
>         static
>         {
>             try
>             {
>                 sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader("mybatis-config.xml"));
>             }
>             catch (IOException e)
>             {
>                 throw new RuntimeException(e);
>             }
>         }
>         //全局的服务器级别的,一个服务器一个即可的
>         private static ThreadLocal<SqlSession> local = new ThreadLocal<>();
>         public static SqlSession openSession()
>         {
>             SqlSession sqlSession = local.get();
>             if(sqlSession == null)
>             {
>                 sqlSession = sqlSessionFactory.openSession();
>                 local.set(sqlSession);
>             }
>             return sqlSession;
>         }
>         public static void close(SqlSession sqlSession)
>         {
>             //关闭SqlSession对象
>             if (sqlSession != null)
>             {
>                 sqlSession.close();
>                 //从当前线程中移除SqlSession对象
>                 //注意一定要一处当前线程和SqlSession对象的绑定关系
>                 //因为Tomcat服务器支持线程池,也就是说用过的线程有概率还会使用这个线程
>                 //如果我们关闭了该SqlSession然后没有移除,就会导致另外的用户有概率拿到这个空的SqlSession对象(已经被关闭了)
>                 local.remove();
>             }
>         }
>     }

>     package com.powernode.bank.service;
>     
>     import com.powernode.bank.exceptions.MoneyNotEnoughException;
>     import com.powernode.bank.exceptions.TransferException;
>     
>     public interface AccountService
>     {
>         //账户业务类
>         void transfer(String from,String to,double money) throws MoneyNotEnoughException, TransferException;
>     }
> 
>     package com.powernode.bank.service;
>     
>     import com.powernode.bank.exceptions.MoneyNotEnoughException;
>     import com.powernode.bank.exceptions.TransferException;
>     
>     public interface AccountService
>     {
>         //账户业务类
>         void transfer(String from,String to,double money) throws MoneyNotEnoughException, TransferException;
>     }

>     package com.powernode.bank.service.Impl;
>     
>     import com.powernode.bank.POJO.Account;
>     import com.powernode.bank.dao.AccountDao;
>     import com.powernode.bank.dao.Impl.AccountDaoImpl;
>     import com.powernode.bank.exceptions.MoneyNotEnoughException;
>     import com.powernode.bank.exceptions.TransferException;
>     import com.powernode.bank.service.AccountService;
>     
>     public class AccountServiceImpl implements AccountService
>     {
>         private AccountDao accountDao = new AccountDaoImpl();
>         @Override
>         //子类抛了父类也得抛异常
>         public void transfer(String from, String to, double money) throws MoneyNotEnoughException, TransferException
>         {
>             //判断转出账户余额是否充足(需要查询语句)
>             Account account = accountDao.selectByActNo(from);
>             if(account.getBalance() < money)
>             {
>                 //如果转出账户余额不足,提示用户
>                 throw new MoneyNotEnoughException("对不起,余额不足");
>             }
>             else
>             {
>                 //如果转出账户余额充足,更新转出余额(Update)
>                 Account toAccount = accountDao.selectByActNo(to);
>                 account.setBalance(account.getBalance() - money);
>                 toAccount.setBalance(toAccount.getBalance() + money);
>                 //更新转入余额(Update)
>                 int count = accountDao.UpdateByActNo(account);
>     //            模拟异常
>                 String s = null;
>                 s.toString();
>                 count = count + accountDao.UpdateByActNo(toAccount);
>                 if(count == 2)
>                 {
>                     accountDao.Commit();
>                     accountDao.close();
>                 }
>                 else
>                 {
>                     accountDao.rollback();
>                     accountDao.close();
>                     throw new TransferException("转账异常,未知原因");
>                 }
>             }
>         }
>     }
> 
>     package com.powernode.bank.service.Impl;
>     
>     import com.powernode.bank.POJO.Account;
>     import com.powernode.bank.dao.AccountDao;
>     import com.powernode.bank.dao.Impl.AccountDaoImpl;
>     import com.powernode.bank.exceptions.MoneyNotEnoughException;
>     import com.powernode.bank.exceptions.TransferException;
>     import com.powernode.bank.service.AccountService;
>     
>     public class AccountServiceImpl implements AccountService
>     {
>         private AccountDao accountDao = new AccountDaoImpl();
>         @Override
>         //子类抛了父类也得抛异常
>         public void transfer(String from, String to, double money) throws MoneyNotEnoughException, TransferException
>         {
>             //判断转出账户余额是否充足(需要查询语句)
>             Account account = accountDao.selectByActNo(from);
>             if(account.getBalance() < money)
>             {
>                 //如果转出账户余额不足,提示用户
>                 throw new MoneyNotEnoughException("对不起,余额不足");
>             }
>             else
>             {
>                 //如果转出账户余额充足,更新转出余额(Update)
>                 Account toAccount = accountDao.selectByActNo(to);
>                 account.setBalance(account.getBalance() - money);
>                 toAccount.setBalance(toAccount.getBalance() + money);
>                 //更新转入余额(Update)
>                 int count = accountDao.UpdateByActNo(account);
>     //            模拟异常
>                 String s = null;
>                 s.toString();
>                 count = count + accountDao.UpdateByActNo(toAccount);
>                 if(count == 2)
>                 {
>                     accountDao.Commit();
>                     accountDao.close();
>                 }
>                 else
>                 {
>                     accountDao.rollback();
>                     accountDao.close();
>                     throw new TransferException("转账异常,未知原因");
>                 }
>             }
>         }
>     }

>     package com.powernode.bank.POJO;
>     
>     public class Account
>     {
>         //封装账户数据
>         private Long id;
>         private String actno;
>         private Double balance;
>     
>         @Override
>         public String toString() {
>             return "Account{" +
>                     "id=" + id +
>                     ", actno='" + actno + '\'' +
>                     ", balance=" + balance +
>                     '}';
>         }
>     
>         public Long getId() {
>             return id;
>         }
>     
>         public void setId(Long id) {
>             this.id = id;
>         }
>     
>         public String getActno() {
>             return actno;
>         }
>     
>         public void setActno(String actno) {
>             this.actno = actno;
>         }
>     
>         public Double getBalance() {
>             return balance;
>         }
>     
>         public void setBalance(Double balance) {
>             this.balance = balance;
>         }
>     
>         public Account(Long id, String actno, Double balance) {
>             this.id = id;
>             this.actno = actno;
>             this.balance = balance;
>         }
>     
>         public Account() {
>         }
>     }
> 
>     package com.powernode.bank.POJO;
>     
>     public class Account
>     {
>         //封装账户数据
>         private Long id;
>         private String actno;
>         private Double balance;
>     
>         @Override
>         public String toString() {
>             return "Account{" +
>                     "id=" + id +
>                     ", actno='" + actno + '\'' +
>                     ", balance=" + balance +
>                     '}';
>         }
>     
>         public Long getId() {
>             return id;
>         }
>     
>         public void setId(Long id) {
>             this.id = id;
>         }
>     
>         public String getActno() {
>             return actno;
>         }
>     
>         public void setActno(String actno) {
>             this.actno = actno;
>         }
>     
>         public Double getBalance() {
>             return balance;
>         }
>     
>         public void setBalance(Double balance) {
>             this.balance = balance;
>         }
>     
>         public Account(Long id, String actno, Double balance) {
>             this.id = id;
>             this.actno = actno;
>             this.balance = balance;
>         }
>     
>         public Account() {
>         }
>     }

>     package com.powernode.bank.exceptions;
>     
>     public class TransferException extends Exception
>     {
>         public TransferException(){};
>         public TransferException(String msg)
>         {
>             super(msg);
>         }
>     }
> 
>     package com.powernode.bank.exceptions;
>     
>     public class TransferException extends Exception
>     {
>         public TransferException(){};
>         public TransferException(String msg)
>         {
>             super(msg);
>         }
>     }

>     package com.powernode.bank.exceptions;
>     
>     public class MoneyNotEnoughException extends Exception
>     {
>         public MoneyNotEnoughException(){};
>         public MoneyNotEnoughException(String msg)
>         {
>             super(msg);
>         }
>     }
> 
>     package com.powernode.bank.exceptions;
>     
>     public class MoneyNotEnoughException extends Exception
>     {
>         public MoneyNotEnoughException(){};
>         public MoneyNotEnoughException(String msg)
>         {
>             super(msg);
>         }
>     }

>     package com.powernode.bank.dao;
>     
>     import com.powernode.bank.POJO.Account;
>     
>     public interface AccountDao
>     {
>         //Dao对象中没有任何一个方法与业务挂钩
>         //没有任何业务在里面
>         //他们只负责进行CRUD
>         //MVC三层架构就是分层职能分工
>         Account selectByActNo(String actNo);
>         //根据账号查询账户信息
>         int UpdateByActNo(Account account);
>         //根据账号更新账户信息
>         void Commit();
>         void close();
>         void rollback();
>     }
> 
>     package com.powernode.bank.dao;
>     
>     import com.powernode.bank.POJO.Account;
>     
>     public interface AccountDao
>     {
>         //Dao对象中没有任何一个方法与业务挂钩
>         //没有任何业务在里面
>         //他们只负责进行CRUD
>         //MVC三层架构就是分层职能分工
>         Account selectByActNo(String actNo);
>         //根据账号查询账户信息
>         int UpdateByActNo(Account account);
>         //根据账号更新账户信息
>         void Commit();
>         void close();
>         void rollback();
>     }

>     package com.powernode.bank.dao.Impl;
>     
>     import com.powernode.bank.POJO.Account;
>     import com.powernode.bank.dao.AccountDao;
>     import com.powernode.bank.utils.SqlSessionUtil;
>     import org.apache.ibatis.session.SqlSession;
>     
>     public class AccountDaoImpl implements AccountDao
>     {
>         //必须保证事务从始至终都是同一个操作对象
>         private SqlSession sqlSession = SqlSessionUtil.openSession();
>         @Override
>         public Account selectByActNo(String actNo)
>         {
>             Account account = (Account)sqlSession.selectOne("account.selectById", actNo);
>             return account;
>         }
>     
>         @Override
>         public int UpdateByActNo(Account account)
>         {
>             int count = sqlSession.update("account.updateById", account);
>             //事务的控制不能放到Dao层去实现
>     //        Commit();
>             return count;
>         }
>         public void Commit()
>         {
>             sqlSession.commit();
>         }
>         public void close()
>         {
>             sqlSession.close();
>         }
>         public void rollback()
>         {
>             sqlSession.rollback();
>         }
>     }
> 
>     package com.powernode.bank.dao.Impl;
>     
>     import com.powernode.bank.POJO.Account;
>     import com.powernode.bank.dao.AccountDao;
>     import com.powernode.bank.utils.SqlSessionUtil;
>     import org.apache.ibatis.session.SqlSession;
>     
>     public class AccountDaoImpl implements AccountDao
>     {
>         //必须保证事务从始至终都是同一个操作对象
>         private SqlSession sqlSession = SqlSessionUtil.openSession();
>         @Override
>         public Account selectByActNo(String actNo)
>         {
>             Account account = (Account)sqlSession.selectOne("account.selectById", actNo);
>             return account;
>         }
>     
>         @Override
>         public int UpdateByActNo(Account account)
>         {
>             int count = sqlSession.update("account.updateById", account);
>             //事务的控制不能放到Dao层去实现
>     //        Commit();
>             return count;
>         }
>         public void Commit()
>         {
>             sqlSession.commit();
>         }
>         public void close()
>         {
>             sqlSession.close();
>         }
>         public void rollback()
>         {
>             sqlSession.rollback();
>         }
>     }