2 个表 1 个 Web 应用程序我该怎么做答案

【问题标题】：2 tables 1 web app what do I do2 个表 1 个 Web 应用程序我该怎么做
【发布时间】：2016-06-25 17:05:09
【问题描述】：

我现在有两个名为 Earnings 和 Passengers 的表我有这些代码

从这里开始查看

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
"http://www.w3.org/TR/html4/loose.dtd">
<html> 
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<form action="mrtservlet" method="post">
Enter first name: <input type="text" name="fname">
Enter last name: <input type="text" name="lname">
Destination: <input type="text" name="dest">
<input type="submit" value="submit">
</form>
</body>
</html>

现在我必须将 fname lname 和 dest 发送到 Passengers 表，如果我将 guadalupe 作为 dest 输入，则 Earnings 必须基于 dest 示例的条目，因此 Earnings 表必须有 1 和 20 的条目，两列有 1是停止号，20 是到达那里的价格

这是我的豆子

package model;

public class earnings {
private int fare;
private int sno;

public int getfare(){
    return fare;
    }
public void setfare(int fare){
    this.fare = fare;
    }
public int getsno(){
    return sno;
    }
public void setsno(int sno){
    this.sno = sno;
    }
}

和

package model;

public class passengers {
private String fname;
private String lname;
private String dest;

public String getfname(){
    return fname;
    }
public void setfname(String fname){
    this.fname = fname;
    }
public String getlname(){
    return lname;
    }
public void setlname(String lname){
    this.lname = lname;
    }
public String getdest(){
    return dest;
    }
public void setdest(String dest){
    this.dest = dest;
    }
}

以及我的 sql 命令和连接实用程序

package utilities;

 import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class earnings_connection {

private static Connection connection = null;

public static Connection getConnection() {
     if (connection != null)
     return connection;
     else {
     try {
     Properties prop = new Properties();
     InputStream=inputStreampassengers_connection.class.getClassLoader().getResourceAsStream("/db.properties0");
     prop.load(inputStream);
     String driver = prop.getProperty("driver");
     String url = prop.getProperty("url");
     String user = prop.getProperty("user");
     String password = prop.getProperty("password");
     Class.forName(driver);
     connection = DriverManager.getConnection(url, user, password);
     } catch (ClassNotFoundException e) {
     e.printStackTrace();
     } catch (SQLException e) {
     e.printStackTrace();
     } catch (FileNotFoundException e) {
     e.printStackTrace();
     } catch (IOException e) {
     e.printStackTrace();
     }
     return connection;
     }
    }   
}

收入连接（上）和乘客连接（下）包实用程序；

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

public class passengers_connection {

private static Connection connection = null;

public static Connection getConnection() {
     if (connection != null)
     return connection;
     else {
     try {
     Properties prop = new Properties();
     InputStream inputStream = passengers_connection.class.getClassLoader().getResourceAsStream("/db.properties");
     prop.load(inputStream);
     String driver = prop.getProperty("driver");
     String url = prop.getProperty("url");
     String user = prop.getProperty("user");
     String password = prop.getProperty("password");
     Class.forName(driver);
     connection = DriverManager.getConnection(url, user, password);
     } catch (ClassNotFoundException e) {
     e.printStackTrace();
     } catch (SQLException e) {
     e.printStackTrace();
     } catch (FileNotFoundException e) {
     e.printStackTrace();
     } catch (IOException e) {
     e.printStackTrace();
     }
     return connection;
     }

    }
    }

表格将首先用于收益的 sql 操作

package utilities;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.List;

import model.earnings;

public class earnings_dao {

private Connection connection;

public earnings_dao(){
    connection = utilities.passengers_connection.getConnection(); 
    }

    public void insertrip(earnings user) { 
        try {
        PreparedStatement preparedStatement = connection
        .prepareStatement("insert into Earnings(Stop No,Fare)"
                + "values (?, ?)");
        preparedStatement.setInt(1, user.getsno());
        preparedStatement.setInt(2, user.getfare());
        preparedStatement.executeUpdate();
        } catch (SQLException e) {
        e.printStackTrace();
        }
    }

    public List<earnings> getAllUsers() {
        List<earnings> users = new ArrayList<earnings>();
        try {
        Statement statement = connection.createStatement();
        ResultSet rs = statement.executeQuery("select Stop No from Earnings");
        while (rs.next()) {
        earnings user = new earnings();
        user.setsno(rs.getInt("Stop No"));
        users.add(user);}
        } catch (SQLException e) {
        e.printStackTrace();
        }
        return users;
    }   
}

现在为乘客

package utilities;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import model.passengers;


public class passengers_dao {

private Connection connection;

public passengers_dao(){
connection = utilities.passengers_connection.getConnection(); 
}

public void insertrip(passengers user) { 
    try {
    PreparedStatement preparedStatement = connection
    .prepareStatement("insert into Passengers(firstname,lastname,destination)"
            + "values (?, ?, ?)");
    preparedStatement.setString(1, user.getfname());
    preparedStatement.setString(2, user.getlname());
    preparedStatement.setString(3, user.getdest());
    preparedStatement.executeUpdate();
    } catch (SQLException e) {
    e.printStackTrace();
    }

   }
}

现在我被我的控制器卡住了，谁能指出我对我的代码所做的任何错误，如果它有助于我使用 MySQL Server Management Studio 创建我尚未完成的数据库及其表，我将不胜感激映射尚未

【问题讨论】：

您缺少 servlet 本身，是否在某处定义了它？您需要告诉应用程序服务器什么是处理 /mrtservlet 路径

标签： java mysql model-view-controller crud

【解决方案1】：

不完全确定问题是什么，但在这个问题中，我没有看到您试图回发的 Servlet 的任何声明，所以我假设这是问题所在：

您可以定义 Servlet 类来处理对定义的 url 完成的 get 和 post 请求。

将在答案中使用类的 JAVA 约定命名，并尝试编写一些希望可以帮助您的代码。

@WebServlet(name = "mrtservlet", urlPatterns = {"/mrtservlet"}})
public class Mrtservlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //do the get stuff if necessary
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //read the post parameters to temporary variables
        String fname= req.getParameter("fname");
        String lname= req.getParameter("lname");
        String dest= req.getParameter("dest");
         // do some null checks on the fields you get from the request

        //fill the earning with what you want and do all the dao related stuf
        Earning earning = new Earning();

        EarningsDao earningsDao= new EarningsDao();
        earningsDao.insert(earning);

        //You can wrap the above code in a switch or a if's if you want to do something different for each dest 
        if(dest!=null && dest.equals("guadalupe")){
         //do guadalupe related stuff
        }

        //redirect to any servlet/page you want you want

        resp.sendRedirect("/servlet");
    }
}

【讨论】：

我已经制作了 servlet，只是我无法理解在 servlet 部分我需要什么的概念
我会尝试在答案中添加更多细节
类名也应该是驼峰式，比如 EarningsDao 而不是 Earnings_dao