MVC 笔记

最新推荐文章于 2022-08-25 16:14:15 发布

李华峰

最新推荐文章于 2022-08-25 16:14:15 发布

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本文链接：https://blog.youkuaiyun.com/linux_lihuafeng/article/details/38422647

本文介绍了一个使用JSP和Servlet实现的学生信息查询系统的具体实现过程，包括web.xml配置、JSP页面展示、Servlet处理逻辑及JavaBean数据操作等关键部分。

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JSP 的优势在于显示表单和显示链接通过表单或链接提交到 servlet

servlet适合纯编程跳转，包含JSP

JSp使用JavaBean

JavaBean可以删除修改数据库结果可以被Jsp使用

MVC

web.xml

===========================================================

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<description>This is the description of my J2EE component</description>
<display-name>This is the display name of my J2EE component</display-name>
<servlet-name>QueryServlet</servlet-name>
<servlet-class>servlet.QueryServlet</servlet-class>
</servlet>

<servlet-mapping>
<servlet-name>QueryServlet</servlet-name>
<url-pattern>/servlet/QueryServlet</url-pattern>
</servlet-mapping>

</web-app>

====================================================================

queryForm.jsp

<%@ page language="java" import="java.util.*" pageEncoding="GBK"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'queryForm.jsp' starting page</title>
</head>

<body>
显示查询.<br>
<form action="/AAA/servlet/QueryServlet" method="post">
学生姓名：<input name="sname"/>
<input type="submit" value="查询结果"/>
</form>
</body>
</html>

====================================================================

QueryServlet

package servlet;
import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import po.Student;
import dao.StudentDao;

public class QueryServlet extends HttpServlet {

public QueryServlet() {
super();
}

public void destroy() {
super.destroy();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//从客户端取到值
String sname = request.getParameter("sname");
//解决tomcat的中文乱码问题
try{
sname = new String(sname.getBytes("ISO-8859-1"));
}catch(Exception e){
e.printStackTrace();
}
//调用JavaBean查询数据库（ Data Access Object 数据访问对象 dao）
StudentDao studentDao = new StudentDao();
//從數據庫中查詢出結果
ArrayList<Student> stus = studentDao.queryStusByName(sname);

//將查詢出的結果暫存在request中
request.setAttribute("stus", stus);
//============================
//跳转到另一个Jsp显示结果

ServletContext application = this.getServletContext();
RequestDispatcher rd = application.getRequestDispatcher("/queryResult.jsp");
rd.forward(request, response);
}

public void init() throws ServletException {
// Put your code here
}

}

========================================================================

StudentDao

package dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import po.Student;
//用于访问数据库
public class StudentDao {

private Connection conn = null;

// 初始化数据库连接
public void initConnection() {
try {
// 载入数据库驱动
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
//初始化Connection
conn = DriverManager.getConnection("jdbc:odbc:School","scott","tiger");//載入數據源
} catch (Exception e) {
e.printStackTrace();
}
}

public ArrayList<Student> queryStusByName(String sname) {

//初始化一個ArrayList容器，，用於存儲查詢結果
ArrayList<Student> stus = new ArrayList<Student>();
//查詢數據庫
String sql = "select * from student where sname = '"+sname+"'";
try {
//打開數據庫連接
this.initConnection();
//查詢出結果集
ResultSet rs = conn.createStatement().executeQuery(sql);
//提取出結果集中的數據
while(rs.next()) {
Student stu = new Student();
stu.setStuId(rs.getString("id"));
stu.setStuName(rs.getString("name"));
stu.setStuSex(rs.getString("sex"));
stu.setStuBirthday(rs.getString("birthday"));
stu.setStuAdress(rs.getString("address"));
stus.add(stu);
}

} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}finally{
//最後，關閉連接
this.closeConnection();
}
//返回查詢結果
return stus;
}
public void closeConnection() {

try{
if(conn !=null){
conn.close();
conn = null;
}

}catch(Exception e){
e.printStackTrace();
}
}

}

=================================================================

Student

package po;
//封裝一個學生的資料
public class Student {

private String stuId;
private String stuName;
private String stuSex;
private String stuAdress;
private String stuBirthday;
public String getStuId() {
return stuId;
}
public void setStuId(String stuId) {
this.stuId = stuId;
}
public String getStuName() {
return stuName;
}
public void setStuName(String stuName) {
this.stuName = stuName;
}
public String getStuSex() {
return stuSex;
}
public void setStuSex(String stuSex) {
this.stuSex = stuSex;
}
public String getStuAdress() {
return stuAdress;
}
public void setStuAdress(String stuAdress) {
this.stuAdress = stuAdress;
}
public String getStuBirthday() {
return stuBirthday;
}
public void setStuBirthday(String stuBirthday) {
this.stuBirthday = stuBirthday;
}

}

================================================================

queryResult.jsp

<%@ page language="java" import="java.util.*" pageEncoding="gb2312"%>
<jsp:directive.page import="po.Student"/> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'queryForm.jsp' starting page</title>
</head>

<body>
显示结果. <br>
<%
ArrayList stus = (ArrayList)request.getAttribute("stus");
%>
<table bgcolor="#ff80ff">
<tr>
<td>学号</td>
<td>姓名</td>
<td>性别</td>
<td>出生年月</td>
<td>家庭住址</td>
</tr>
<%
for(int i=0;i<stus.size();i++){
Student stu = (Student)stus.get(i);
%>
<tr>
<td><%=stu.getStuId() %></td>
<td><%=stu.getStuName() %></td>
<td><%=stu.getStuSex() %></td>
<td><%=stu.getStuBirthday() %></td>
<td><%=stu.getStuAdress()%></td>
</tr>
<%
}
%>
</table>
</body>
</html>

================================================================

在这个小实例里，，queryForm.jsp 和 queryResult.jsp 属于View

QueryServlet 属于Controllcor

StudentDao{体现逻辑}、Student{体现状态} 属于 Model