JAVA-EE在不使用MVC分层的情况下用一个servlet完成转账业务------Java-Web项目

在不使用MVC分层的情况下用一个servlet完成转账业务

package com.bjpowernode.Bank.servlet;

import com.bjpowernode.Bank.exception.AppException;
import com.bjpowernode.Bank.exception.MoneyNotEnoughException;
import com.bjpowernode.oa.utils.DBUtil;
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;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

//@WebServlet("/bank/transfer")
public class AccountTransferServlet extends HttpServlet
{
    //当前Servlet实际上负责了
    //数据接收,核心业务处理,CRUD操作,界面的数据展示
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        String fromActno = request.getParameter("fromActno");
        String toActno = request.getParameter("toActno");
        Double value = Double.parseDouble(request.getParameter("Value"));
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        PreparedStatement statement1 = null;
        PreparedStatement statement2 = null;
        try
        {
            connection = DBUtil.getConnection();
            connection.setAutoCommit(false);
            String sql = "select * from t_act where actno = ?";
            statement = connection.prepareStatement(sql);
            statement.setString(1,fromActno);
            resultSet = statement.executeQuery();
            if(resultSet.next())
            {
                System.out.println("我在这");
                double balance = resultSet.getDouble("balance");
                System.out.println(balance);
                if(balance < value)
                {
                    //余额不足
                    throw new MoneyNotEnoughException("余额不足");
                }
                else
                {
                    String newSql = "update t_act set balance = balance - ? where actno = ?";
                    statement1 = connection.prepareStatement(newSql);
                    statement1.setDouble(1,value);
                    statement1.setString(2,fromActno);
                    int count = statement1.executeUpdate();
                    String sql2 = "update t_act set balance = balance + ? where actno = ?";
                    statement2 = connection.prepareStatement(sql2);
                    statement2.setDouble(1,value);
                    statement2.setString(2,toActno);
                    count = count + statement2.executeUpdate();
                    if(count != 2)
                    {
                        throw new AppException("App异常请联系管理员");
                    }
                    else
                    {
                        connection.commit();
                        out.println("转账成功");
                    }
                }
            }
        }
        catch (Exception e)
        {
            if (connection != null)
            {
                try
                {
                    connection.rollback();
                }
                catch (SQLException ex)
                {
                    throw new RuntimeException(ex);
                }
            }
            //传的一定是构造方法我们传的值
            out.println(e.getMessage());
        }
        finally
        {
            DBUtil.close(connection,statement,resultSet);
            DBUtil.close(null,statement1,null);
            DBUtil.close(null,statement2,null);
        }
    }
}