j2ee—框架（1）：Servlet+JSP实现基本的登录功能（v1.0）

Mister24

发布于 2018-05-14 10:23:11

9350

发布于 2018-05-14 10:23:11

主要分为四个部分：LoginController、web.xml、login.jsp和login_success.jsp(login_fail.jsp)。

第一部分 LoginController

 1     protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 2         // TODO Auto-generated method stub
 3         ServletContext servletContext = getServletContext();
 4         RequestDispatcher requestDispatcher = null;
 5         
 6         String name = request.getParameter("name");
 7         System.out.println(name);
 8         String password = request.getParameter("password");
 9         
10         //if("ustc".equals(name)&&"oreo".equals(password))
11         if(name.equals(password))
12         {
13             System.out.println("123");
14             requestDispatcher = servletContext.getRequestDispatcher("/login_success.jsp");
15         }
16         else
17         {
18             requestDispatcher = servletContext.getRequestDispatcher("/login_fail.jsp");
19         }
20         
21         
22         requestDispatcher.forward(request, response);
23         
24         //response.getWriter().append("Served at: ").append(request.getContextPath());
25     }
26 
27     /**
28      * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
29      */
30     protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
31         // TODO Auto-generated method stub
32         doGet(request, response);
33     }

在这一部分，用LoginController实现了跳转不同页面的处理，如果账号和密码是正确的，则跳转到login_success.jsp的页面，否则跳转到login_fail.jsp的页面。

第二部分 web.xml 在这里，先看<servlet-mapping>中的内容，如果url后半部分是/action/a1，则将该部分交给Controller的LoginController处理。

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
 3   <display-name>Controller</display-name>
 4   <welcome-file-list>
 5     <welcome-file>index.html</welcome-file>
 6     <welcome-file>index.htm</welcome-file>
 7     <welcome-file>index.jsp</welcome-file>
 8     <welcome-file>default.html</welcome-file>
 9     <welcome-file>default.htm</welcome-file>
10     <welcome-file>default.jsp</welcome-file>
11   </welcome-file-list>
12   
13   <servlet>
14       <servlet-name>Controller</servlet-name>
15       <servlet-class>hello.LoginController</servlet-class>
16   </servlet>
17   
18   <servlet-mapping>
19       <servlet-name>Controller</servlet-name>
20       <url-pattern>/action/a1</url-pattern>
21   </servlet-mapping>
22 </web-app>

第三部分 login.jsp 在这里，声明了action="action/a1"，所以会被交给servlet处理，servlet才能用String类型的数据将name和password保存下来，然后用来作为判定条件，从而跳转到相应的页面。

 1 <%@ page language="java" contentType="text/html; charset=utf-8"
 2     pageEncoding="utf-8"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 <form action="action/a1" method="post">
11     <label>账号：</label><input type="text" name="name"></br>
12     <label>密码：</label><input type="text" name="password"></br>
13     <input type="submit" value="登录">
14 </form>
15 </body>
16 </html>

第四部分 login_success.jsp和login_fail.jsp

 1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 2     pageEncoding="ISO-8859-1"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 Welcome!
11 </body>
12 </html>

login_success.jsp代码

 1 <%@ page language="java" contentType="text/html; charset=ISO-8859-1"
 2     pageEncoding="ISO-8859-1"%>
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
 4 <html>
 5 <head>
 6 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
 7 <title>Insert title here</title>
 8 </head>
 9 <body>
10 Failed!
11 </body>
12 </html>

login_fail.jsp代码

运行截图