JAVA-EE在MVC模式下ThreadLocal保证事务完成银行转账业务------计算机网络经典

忘是亡心i 2024-02-20 10:00 82阅读 0赞

>     package com.bjpowernode.Bank.utils;
>     
>     import java.sql.*;
>     import java.util.ResourceBundle;
>     
>     public class DBUtil
>     {
>         private static ThreadLocal<Connection> threadLocal = new ThreadLocal<>();
>         private static ResourceBundle bundle = ResourceBundle.getBundle("resources.jdbc");
>         private static String driver = bundle.getString("driver");
>         private static String url = bundle.getString("url");
>         private static String user = bundle.getString("user");
>         private static String password = bundle.getString("password");
>         //JDBC工具类
>         static
>         {
>             //注册驱动
>             try
>             {
>     //            Class.forName("com.mysql.jdbc.Driver");//避免写死
>                 Class.forName(driver);
>             }
>             catch (ClassNotFoundException e)
>             {
>                 throw new RuntimeException(e);
>             }
>         }
>         public static Connection getConnection() throws SQLException {
>             //获取链接
>             Connection connection = threadLocal.get();
>             if(connection == null)
>             {
>                 connection = DriverManager.getConnection(url,user,password);
>                 threadLocal.set(connection);
>             }
>             return connection;
>         }
>         //释放资源
>         public static void close(Connection connection, Statement statement, ResultSet resultSet)
>         {
>             if (resultSet != null) {
>                 try {
>                     resultSet.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (statement != null) {
>                 try {
>                     statement.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (connection != null) {
>                 try {
>                     connection.close();
>                     //因为Tomcat服务器内置了一个线程池
>                     //线程池内置了很多创建好的线程对象
>                     //存在重复使用的可能,如果没有移除,就会导致另一个分配到这个线程的人
>                     //会导致获取到已经关闭的connection对象
>                     threadLocal.remove();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>         }
>     }
> 
>     package com.bjpowernode.Bank.utils;
>     
>     import java.sql.*;
>     import java.util.ResourceBundle;
>     
>     public class DBUtil
>     {
>         private static ThreadLocal<Connection> threadLocal = new ThreadLocal<>();
>         private static ResourceBundle bundle = ResourceBundle.getBundle("resources.jdbc");
>         private static String driver = bundle.getString("driver");
>         private static String url = bundle.getString("url");
>         private static String user = bundle.getString("user");
>         private static String password = bundle.getString("password");
>         //JDBC工具类
>         static
>         {
>             //注册驱动
>             try
>             {
>     //            Class.forName("com.mysql.jdbc.Driver");//避免写死
>                 Class.forName(driver);
>             }
>             catch (ClassNotFoundException e)
>             {
>                 throw new RuntimeException(e);
>             }
>         }
>         public static Connection getConnection() throws SQLException {
>             //获取链接
>             Connection connection = threadLocal.get();
>             if(connection == null)
>             {
>                 connection = DriverManager.getConnection(url,user,password);
>                 threadLocal.set(connection);
>             }
>             return connection;
>         }
>         //释放资源
>         public static void close(Connection connection, Statement statement, ResultSet resultSet)
>         {
>             if (resultSet != null) {
>                 try {
>                     resultSet.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (statement != null) {
>                 try {
>                     statement.close();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>             if (connection != null) {
>                 try {
>                     connection.close();
>                     //因为Tomcat服务器内置了一个线程池
>                     //线程池内置了很多创建好的线程对象
>                     //存在重复使用的可能,如果没有移除,就会导致另一个分配到这个线程的人
>                     //会导致获取到已经关闭的connection对象
>                     threadLocal.remove();
>                 } catch (SQLException e) {
>                     throw new RuntimeException(e);
>                 }
>             }
>         }
>     }

>     package com.bjpowernode.Bank.servlet;
>     
>     import com.bjpowernode.Bank.service.AccountService;
>     import com.bjpowernode.Bank.service.Impl.AccountServiceImpl;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     
>     import java.io.IOException;
>     import java.io.PrintWriter;
>     
>     @WebServlet("/bank/transfer")
>     public class AccountServlet extends HttpServlet
>     {
>         private AccountService accountService = new AccountServiceImpl();
>         @Override
>         protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             //接收数据
>             String fromActno = request.getParameter("fromActno");
>             String toActno = request.getParameter("toActno");
>             Double value = Double.valueOf(request.getParameter("Value"));
>             response.setContentType("text/html;charset=UTF-8");
>             PrintWriter out = response.getWriter();
>             try
>             {
>                 accountService.transfer(fromActno,toActno,value);
>                 out.println("转账成功");
>             }
>             catch (Exception e)
>             {
>                 out.println(e.getMessage());
>             }
>         }
>     }
> 
>     package com.bjpowernode.Bank.servlet;
>     
>     import com.bjpowernode.Bank.service.AccountService;
>     import com.bjpowernode.Bank.service.Impl.AccountServiceImpl;
>     import jakarta.servlet.ServletException;
>     import jakarta.servlet.annotation.WebServlet;
>     import jakarta.servlet.http.HttpServlet;
>     import jakarta.servlet.http.HttpServletRequest;
>     import jakarta.servlet.http.HttpServletResponse;
>     
>     import java.io.IOException;
>     import java.io.PrintWriter;
>     
>     @WebServlet("/bank/transfer")
>     public class AccountServlet extends HttpServlet
>     {
>         private AccountService accountService = new AccountServiceImpl();
>         @Override
>         protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException
>         {
>             //接收数据
>             String fromActno = request.getParameter("fromActno");
>             String toActno = request.getParameter("toActno");
>             Double value = Double.valueOf(request.getParameter("Value"));
>             response.setContentType("text/html;charset=UTF-8");
>             PrintWriter out = response.getWriter();
>             try
>             {
>                 accountService.transfer(fromActno,toActno,value);
>                 out.println("转账成功");
>             }
>             catch (Exception e)
>             {
>                 out.println(e.getMessage());
>             }
>         }
>     }

>     package com.bjpowernode.Bank.service;
>     
>     import com.bjpowernode.Bank.Dao.AccountDao;
>     import com.bjpowernode.Bank.exception.MoneyNotEnoughException;
>     
>     public interface AccountService
>     {
>         //业务类,专注于业务处理
>         //不写别的,只处理业务信息
>         void transfer(String fromActno,String toActno,double money) throws Exception;
>     }
> 
>     package com.bjpowernode.Bank.service;
>     
>     import com.bjpowernode.Bank.Dao.AccountDao;
>     import com.bjpowernode.Bank.exception.MoneyNotEnoughException;
>     
>     public interface AccountService
>     {
>         //业务类,专注于业务处理
>         //不写别的,只处理业务信息
>         void transfer(String fromActno,String toActno,double money) throws Exception;
>     }

>     package com.bjpowernode.Bank.service.Impl;
>     
>     import com.bjpowernode.Bank.Dao.AccountDao;
>     import com.bjpowernode.Bank.Dao.Impl.AccountDaoImpl;
>     import com.bjpowernode.Bank.Pojo.Account;
>     import com.bjpowernode.Bank.exception.AppException;
>     import com.bjpowernode.Bank.exception.MoneyNotEnoughException;
>     import com.bjpowernode.Bank.service.AccountService;
>     import com.bjpowernode.Bank.utils.DBUtil;
>     
>     import java.sql.Connection;
>     import java.sql.SQLException;
>     
>     public class AccountServiceImpl implements AccountService
>     {
>         private AccountDao accountDao = new AccountDaoImpl();
>         @Override
>         public void transfer(String fromActno, String toActno, double money) throws Exception {
>             //在service层开启事务
>             try
>             {
>                 Connection connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 Account fromAccount = accountDao.selectByActno(fromActno);
>                 if(fromAccount.getBalance() < money)
>                 {
>                     throw new MoneyNotEnoughException("余额不足");
>                 }
>                 Account toAccount = accountDao.selectByActno(toActno);
>                 fromAccount.setBalance(fromAccount.getBalance() - money);
>                 toAccount.setBalance(toAccount.getBalance() + money);
>                 int count = accountDao.update(fromAccount);
>                 count = count + accountDao.update(toAccount);
>                 if(count != 2)
>                 {
>                     throw new AppException("转账失败");
>                 }
>                 connection.commit();
>             }
>             catch(SQLException e)
>             {
>                 throw new AppException("转账异常,请联系客服");
>             }
>             finally
>             {
>                 DBUtil.close(DBUtil.getConnection(),null,null);
>             }
>         }
>     }
> 
>     package com.bjpowernode.Bank.service.Impl;
>     
>     import com.bjpowernode.Bank.Dao.AccountDao;
>     import com.bjpowernode.Bank.Dao.Impl.AccountDaoImpl;
>     import com.bjpowernode.Bank.Pojo.Account;
>     import com.bjpowernode.Bank.exception.AppException;
>     import com.bjpowernode.Bank.exception.MoneyNotEnoughException;
>     import com.bjpowernode.Bank.service.AccountService;
>     import com.bjpowernode.Bank.utils.DBUtil;
>     
>     import java.sql.Connection;
>     import java.sql.SQLException;
>     
>     public class AccountServiceImpl implements AccountService
>     {
>         private AccountDao accountDao = new AccountDaoImpl();
>         @Override
>         public void transfer(String fromActno, String toActno, double money) throws Exception {
>             //在service层开启事务
>             try
>             {
>                 Connection connection = DBUtil.getConnection();
>                 connection.setAutoCommit(false);
>                 Account fromAccount = accountDao.selectByActno(fromActno);
>                 if(fromAccount.getBalance() < money)
>                 {
>                     throw new MoneyNotEnoughException("余额不足");
>                 }
>                 Account toAccount = accountDao.selectByActno(toActno);
>                 fromAccount.setBalance(fromAccount.getBalance() - money);
>                 toAccount.setBalance(toAccount.getBalance() + money);
>                 int count = accountDao.update(fromAccount);
>                 count = count + accountDao.update(toAccount);
>                 if(count != 2)
>                 {
>                     throw new AppException("转账失败");
>                 }
>                 connection.commit();
>             }
>             catch(SQLException e)
>             {
>                 throw new AppException("转账异常,请联系客服");
>             }
>             finally
>             {
>                 DBUtil.close(DBUtil.getConnection(),null,null);
>             }
>         }
>     }

>     package com.bjpowernode.Bank.Pojo;
>     
>     public class Account
>     {
>         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.bjpowernode.Bank.Pojo;
>     
>     public class Account
>     {
>         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.bjpowernode.Bank.exception;
>     
>     public class MoneyNotEnoughException extends Exception
>     {
>         public MoneyNotEnoughException(){}
>         public MoneyNotEnoughException(String msg){super(msg);}
>     }
> 
>     package com.bjpowernode.Bank.exception;
>     
>     public class MoneyNotEnoughException extends Exception
>     {
>         public MoneyNotEnoughException(){}
>         public MoneyNotEnoughException(String msg){super(msg);}
>     }

>     package com.bjpowernode.Bank.exception;
>     
>     public class AppException extends Exception
>     {
>         public AppException(){}
>     
>         public AppException(String message) {
>             super(message);
>         }
>     }
> 
>     package com.bjpowernode.Bank.exception;
>     
>     public class AppException extends Exception
>     {
>         public AppException(){}
>     
>         public AppException(String message) {
>             super(message);
>         }
>     }

>     package com.bjpowernode.Bank.Dao;
>     
>     import com.bjpowernode.Bank.Pojo.Account;
>     
>     import java.util.List;
>     
>     public interface AccountDao
>     {
>         //DAO,Data Access Object数据访问对象
>         //取名规范取决于处理的表名字
>         int insert(Account account);
>         int deleteByActno(Long id);
>         int update(Account account);
>         Account selectByActno(String actno);
>         List<Account> selectAll();
>     }
> 
>     package com.bjpowernode.Bank.Dao;
>     
>     import com.bjpowernode.Bank.Pojo.Account;
>     
>     import java.util.List;
>     
>     public interface AccountDao
>     {
>         //DAO,Data Access Object数据访问对象
>         //取名规范取决于处理的表名字
>         int insert(Account account);
>         int deleteByActno(Long id);
>         int update(Account account);
>         Account selectByActno(String actno);
>         List<Account> selectAll();
>     }

>     package com.bjpowernode.Bank.Dao.Impl;
>     
>     import com.bjpowernode.Bank.Dao.AccountDao;
>     import com.bjpowernode.Bank.Pojo.Account;
>     import com.bjpowernode.Bank.utils.DBUtil;
>     
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     import java.util.ArrayList;
>     import java.util.List;
>     
>     public class AccountDaoImpl implements AccountDao
>     {
>         @Override
>         public int insert(Account account)
>         {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "insert into t_act(id,actno,balance) values(?,?,?)";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,null);
>                 statement.setString(2,account.getActno());
>                 statement.setDouble(3,account.getBalance());
>                 count = statement.executeUpdate();
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return count;
>         }
>     
>         @Override
>         public int deleteByActno(Long id) {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "delete from t_act where id = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setLong(1,id);
>                 count = statement.executeUpdate();
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return count;
>         }
>     
>         @Override
>         public int update(Account account) {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "update t_act set actno = ?,balance = ? where id = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,account.getActno());
>                 statement.setDouble(2,account.getBalance());
>                 statement.setLong(3,account.getId());
>                 count = statement.executeUpdate();
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return count;
>         }
>     
>         @Override
>         public Account selectByActno(String actno) {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             Account account = new Account();
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from t_act where actno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,actno);
>                 resultSet = statement.executeQuery();
>                 if(resultSet.next())
>                 {
>                     account.setActno(actno);
>                     Long id = resultSet.getLong("id");
>                     account.setId(id);
>                     double balance = resultSet.getDouble("balance");
>                     account.setBalance(balance);
>                 }
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return account;
>         }
>     
>         @Override
>         public List<Account> selectAll() {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             List<Account> list = null;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from t_act";
>                 statement = connection.prepareStatement(sql);
>                 resultSet = statement.executeQuery();
>                 while(resultSet.next())
>                 {
>                     list = new ArrayList<Account>();
>                     Account account = new Account();
>                     String actno = resultSet.getString("actno");
>                     account.setActno(actno);
>                     Long id = resultSet.getLong("id");
>                     account.setId(id);
>                     double balance = resultSet.getDouble("balance");
>                     account.setBalance(balance);
>                     list.add(account);
>                 }
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return list;
>         }
>     }
> 
>     package com.bjpowernode.Bank.Dao.Impl;
>     
>     import com.bjpowernode.Bank.Dao.AccountDao;
>     import com.bjpowernode.Bank.Pojo.Account;
>     import com.bjpowernode.Bank.utils.DBUtil;
>     
>     import java.sql.Connection;
>     import java.sql.PreparedStatement;
>     import java.sql.ResultSet;
>     import java.sql.SQLException;
>     import java.util.ArrayList;
>     import java.util.List;
>     
>     public class AccountDaoImpl implements AccountDao
>     {
>         @Override
>         public int insert(Account account)
>         {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "insert into t_act(id,actno,balance) values(?,?,?)";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,null);
>                 statement.setString(2,account.getActno());
>                 statement.setDouble(3,account.getBalance());
>                 count = statement.executeUpdate();
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return count;
>         }
>     
>         @Override
>         public int deleteByActno(Long id) {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "delete from t_act where id = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setLong(1,id);
>                 count = statement.executeUpdate();
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return count;
>         }
>     
>         @Override
>         public int update(Account account) {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             int count = 0;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "update t_act set actno = ?,balance = ? where id = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,account.getActno());
>                 statement.setDouble(2,account.getBalance());
>                 statement.setLong(3,account.getId());
>                 count = statement.executeUpdate();
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return count;
>         }
>     
>         @Override
>         public Account selectByActno(String actno) {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             Account account = new Account();
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from t_act where actno = ?";
>                 statement = connection.prepareStatement(sql);
>                 statement.setString(1,actno);
>                 resultSet = statement.executeQuery();
>                 if(resultSet.next())
>                 {
>                     account.setActno(actno);
>                     Long id = resultSet.getLong("id");
>                     account.setId(id);
>                     double balance = resultSet.getDouble("balance");
>                     account.setBalance(balance);
>                 }
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return account;
>         }
>     
>         @Override
>         public List<Account> selectAll() {
>             ResultSet resultSet = null;
>             PreparedStatement statement = null;
>             Connection connection = null;
>             List<Account> list = null;
>             try
>             {
>                 connection = DBUtil.getConnection();
>                 String sql = "select * from t_act";
>                 statement = connection.prepareStatement(sql);
>                 resultSet = statement.executeQuery();
>                 while(resultSet.next())
>                 {
>                     list = new ArrayList<Account>();
>                     Account account = new Account();
>                     String actno = resultSet.getString("actno");
>                     account.setActno(actno);
>                     Long id = resultSet.getLong("id");
>                     account.setId(id);
>                     double balance = resultSet.getDouble("balance");
>                     account.setBalance(balance);
>                     list.add(account);
>                 }
>             }
>             catch (SQLException e)
>             {
>                 throw new RuntimeException(e);
>             }
>             finally
>             {
>                 DBUtil.close(null,statement,resultSet);
>             }
>             return list;
>         }
>     }