3.servlet实现页面的跳转

效果：

在网页的输入框中输入lily,跳到成功的页面（请求转发），输入的不是lily则跳到百度的页面（跳到工程之外的页面，则是请求重定向）

　　1.建Web project“2Servlet_Basic”，在src文件夹下建MyHtml.html

<!DOCTYPE html>
<html>
  <head>
    <title>MyHtml.html</title>
 
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
   
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
  </head>
 
  <body>
    <form action="/2Servlet_Basic/servlet/basic" method="post">
     <input type="submit" value ="click">
     usename:
        <input type="text" name="usename" >
    </form>
  </body>
</html>

<!--success.html-->
<!DOCTYPE html>
<html>
  <head>
    <title>success.html</title>
 
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
   
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
  </head>
 
  <body>
    success! <br>
  </body>
</html>

<!--failure.html-->
<!DOCTYPE html>
<html>
  <head>
    <title>failure.html</title>
 
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="this is my page">
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
   
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
  </head>
 
  <body>
    failure! <br>
  </body>
</html>

2.在web.xml中加入usename的局部变量（是这个servlet实例能够调用它）

<?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> 
<servlet-name>basicservlet</servlet-name> 
<servlet-class>com.amaker.servlet.ServletBasic</servlet-class> 
<init-param> 
<param-name>usename</param-name> 
<param-value>lily</param-value> 
</init-param> 
</servlet> 
<servlet-mapping> 
<servlet-name>basicservlet</servlet-name> 
<url-pattern>/servlet/basic</url-pattern> 
</servlet-mapping> 
<welcome-file-list> 
<welcome-file>index.jsp</welcome-file> 
</welcome-file-list> 
<login-config> 
<auth-method>BASIC</auth-method> 
</login-config> 
</web-app>

3..在工程下建包com.amaker.servlet，在包下建类“ServletBasic.java”

//ServletBasic.java
package com.amaker.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//继承HttpServet,doGet alt+/,sysout alt+/
public class ServletBasic extends HttpServlet {
 /**
  *
  */
 private static final long serialVersionUID = 3616093822222878695L;
 public void init() throws ServletException {
   System.out.println("init");
 }
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
   System.out.println("doGet");
 }
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
   System.out.println("doPost");
 }
 protected void service(HttpServletRequest  request, HttpServletResponse response)
   throws ServletException, IOException {
   String usename=request.getParameter("usename");
   if(usename!=null&usename.equals("lily")){
    request.getRequestDispatcher("/success.html").forward(request, response);
//跳到工程里的页面，叫做请求转发
   }else{
//     request.getRequestDispatcher("/failure.html").forward(request, response); 
    response.sendRedirect("http://www.google.cn");
//跳到工程之外的页面，请求重定向
   }
//如果表单上填写的usename 为Lily，则跳转到成功的页面,否则跳转到失败的页面
//提交表单后第一个将调用service方法
 }
 public void destroy() {
   System.out.println("destroy");
 }
 
 
}

------------------------------------------------------------------------------------------------------------------------------本娃的学习日记@lily园