一、前言
本文 MVC 模式的一个简单案例,可以作为 练习 MVC 模式进行测试,建议不了解 MVC 模式 的小伙伴可以先去学习一下。
二、功能要求:
要求实现根据航班号查询航班信息的功能。
(a) 初始面面为查询页面，用户在该页面输入要查询的航班号，如图1所示
(b) 用户输入航班号，点击“搜索航班”按钮时，系统将校验用户输入内容，当用户没有输入航班号直接点击“搜索航班”按钮时，将给出提示信息，如图2所示
(c) 用户输入航班号并点击“搜索航班”按钮后，系统提交该查询请求，并在查询结果页面上显示满足条件的航班信息，如图3所示
(d) 当系统没有找到该航班的信息时，在查询页面上显示提示信息。用户点击“返回”按钮时，页面回到查询页面，如图4所示
三、代码展示:
View:
index.jsp:
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<form action="FlightServlet" method="post">
<span style="color: red">${space}</span> <br>
<h2>航班信息查询</h2>
请输入航班号:<input type="text" name = "flightNumber">
<input type="submit" value="搜索航班">
</form>
</body>
</html>
info.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>Title</title>
</head>
<body>
查询结果:
<c:choose>
<c:when test="${requestScope.error == null }">
<table border="2">
<tr bgcolor="red">
<td>航班号</td>
<td>航空公司</td>
<td>出发机场</td>
<td>到达机场</td>
<td>出发时间</td>
<td>到达时间</td>
<td>机型</td>
</tr>
<tr>
<td>${flightinfo.flightid}</td>
<td>${flightinfo.company}</td>
<td>${flightinfo.leaveairport}</td>
<td>${flightinfo.arriveairport}</td>
<td>${flightinfo.leavetime}</td>
<td>${flightinfo.arrivetime}</td>
<td>${flightinfo.airplane}</td>
</tr>
</table>
</c:when>
<c:otherwise>
${error}
</c:otherwise>
</c:choose>
<a href="index.jsp">回到首页</a>
</body>
</html>
Model层:
==实体部分JavaBean:对应 数据库中表。 ==
package rj.entity;
public class FlightInfo {
private int id;
private String flightid;
private String company;
private String leaveairport;
private String arriveairport;
private String leavetime;
private String arrivetime;
private String airplane;
public FlightInfo(){};
public FlightInfo(String flightid, String company, String leaveairport, String arriveairport, String leavetime, String arrivetime, String airplane) {
this.flightid = flightid;
this.company = company;
this.leaveairport = leaveairport;
this.arriveairport = arriveairport;
this.leavetime = leavetime;
this.arrivetime = arrivetime;
this.airplane = airplane;
}
public FlightInfo(int id, String flightid, String company, String leaveairport, String arriveairport, String leavetime, String arrivetime, String airplane) {
this.id = id;
this.flightid = flightid;
this.company = company;
this.leaveairport = leaveairport;
this.arriveairport = arriveairport;
this.leavetime = leavetime;
this.arrivetime = arrivetime;
this.airplane = airplane;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFlightid() {
return flightid;
}
public void setFlightid(String flightid) {
this.flightid = flightid;
}
public String getCompany() {
return company;
}
public void setCompany(String company) {
this.company = company;
}
public String getLeaveairport() {
return leaveairport;
}
public void setLeaveairport(String leaveairport) {
this.leaveairport = leaveairport;
}
public String getArriveairport() {
return arriveairport;
}
public void setArriveairport(String arriveairport) {
this.arriveairport = arriveairport;
}
public String getLeavetime() {
return leavetime;
}
public void setLeavetime(String leavetime) {
this.leavetime = leavetime;
}
public String getArrivetime() {
return arrivetime;
}
public void setArrivetime(String arrivetime) {
this.arrivetime = arrivetime;
}
public String getAirplane() {
return airplane;
}
public void setAirplane(String airplane) {
this.airplane = airplane;
}
@Override
public String toString() {
return "FlightInfo{" +
"flightid='" + flightid + '\'' +
", company='" + company + '\'' +
", leaveairport='" + leaveairport + '\'' +
", arriveairport='" + arriveairport + '\'' +
", leavetime='" + leavetime + '\'' +
", arrivetime='" + arrivetime + '\'' +
", airplane='" + airplane + '\'' +
'}';
}
}
Dao 层:
package rj.dao;
import rj.entity.FlightInfo;
import rj.util.DBUtil;
import java.sql.ResultSet;
import java.sql.SQLException;
public class FlightDao {
public FlightInfo findByFlightNumber(String flightNumber) throws SQLException {
String sql = "select * from flightinfo where flightid = ?";
Object[] params = {flightNumber};
ResultSet rs = DBUtil.excucateQuery(sql, params);
while(rs.next()) {
String flightid = rs.getString("flightid");
String company = rs.getString("company");
String leaveairport = rs.getString("leaveairport");
String arriveairport = rs.getString("arriveairport");
String leavetime = rs.getString("leavetime");
String arrivetime = rs.getString("arrivetime");
String airplane = rs.getString("airplane");
FlightInfo flightInfo = new FlightInfo(flightid,company,leaveairport,arriveairport,leavetime,arrivetime,airplane);
System.out.println(flightInfo);
return flightInfo;
}
return null;
}
}
DBUtil:数据库工具类:
package rj.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/*
* 数据库帮助类:可以简化代码(将每个模块中重复的代码弄到一个方法中,增加代码复用)
* DBUtil: 简化 Dao 层的代码
*
* */
public class DBUtil {
private static final String URL = "jdbc:mysql://localhost:3306/flight?useSSL=false&&serverTimezone=UTC";
private static final String User = "root";
private static final String Password = "root";
public static Connection conn = null;
public static PreparedStatement pstam = null;
public static ResultSet rs = null;
public static Connection getConnection() throws ClassNotFoundException, SQLException {
Class.forName("com.mysql.cj.jdbc.Driver") ;
return DriverManager.getConnection( URL,User,Password ) ;
}
public static PreparedStatement createPreParedStatement(String sql,Object[] params) throws ClassNotFoundException, SQLException {
pstam = getConnection().prepareStatement(sql) ;
if(params!=null ) {
for(int i=0;i<params.length;i++) {
pstam.setObject(i+1, params[i]);
}
}
return pstam;
}
public static boolean exeucateUpdate(String sql,Object[] pstams) {
int result = 0;
try {
pstam = createPreParedStatement(sql,pstams);
result = pstam.executeUpdate();
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} finally {
try {
if(rs != null) rs.close();
if(pstam != null) pstam.close();
if(conn != null) conn.close();
} catch(SQLException e) {
e.printStackTrace();
}
}
if(result > 0) return true;
else return false;
}
public static ResultSet excucateQuery(String sql, Object[] pstams) {
try {
pstam = createPreParedStatement(sql,pstams);
rs = pstam.executeQuery();
return rs;
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
Cotroller层:
业务逻辑层:
package rj.servlet;
import rj.dao.FlightDao;
import rj.entity.FlightInfo;
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;
import java.sql.SQLException;
@WebServlet(urlPatterns = "/FlightServlet")
public class FlightServlet extends HttpServlet {
private FlightDao flightDao = new FlightDao();
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String flightNumber = request.getParameter("flightNumber");
System.out.println("...............................................................................");
System.out.println(flightNumber);
if(flightNumber.equals("") || flightNumber.trim().equals("")) {
request.setAttribute("space","Sorry,您还没有输入航班号哦!");
request.getRequestDispatcher("/index.jsp").forward(request,response);
return;
}
try {
FlightInfo flightinfo = flightDao.findByFlightNumber(flightNumber);
if(flightinfo != null) {
request.setAttribute("flightinfo",flightinfo);
} else {
request.setAttribute("error","没有该航班信息!");
}
request.getRequestDispatcher("/info.jsp").forward(request,response);
} catch (SQLException e) {
e.printStackTrace();
}
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request,response);
}
}
四、效果展示:
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