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One:
1. Introduction of Knowledge points
1). Essential difference: The forwarding of the request only makes one request, while the redirect makes two requests.
Specific:
①. Forwarding of requests: The Address bar is the address where the request was first made.
REDIRECT requested: The Address bar is no longer the initial request address. Address bar is the last address that responds
②. Request forwarding: In the final Servlet, the request object and the requested request in transit are the same object.
Request redirection: In the final Servlet, the request object and the requested request in transit are not the same object.
③. Forwarding of requests: resources that can only be forwarded to the current WEB app
REDIRECT requested: can be redirected to any resource.
④. Forwarding of requests:/represents the root directory of the current WEB app
REDIRECT requested:/represents the root directory of the current WEB site.
Two: procedure
1.web.xml (about configuration using annotations)
1 <?XML version= "1.0" encoding= "UTF-8"?>2 <Web-appXmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"3 xmlns= "Http://xmlns.jcp.org/xml/ns/javaee"4 xsi:schemalocation= "Http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"5 ID= "webapp_id"version= "3.1">6 <Display-name>Jsptest</Display-name>7 </Web-app>
2.jsp files (two links representing two points of knowledge)
1<%@ page language= "java" contenttype= "text/html; Charset=iso-8859-1 "2pageencoding= "Iso-8859-1"%>3<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "HTTP://WWW.W3.ORG/TR/HTML4/LOOSE.DTD" >456<meta http-equiv= "Content-type" content= "text/html; Charset=iso-8859-1 ">7<title>insert title here</title>89<body>Ten<!--Request Forwarding-- One<a href= "ForwardServlet" >Forward</a> A -<br><br> - the<!--redirects-- -<a href= "Redirectservlet" >RedirectServlet</a> -</body> -3.forwardservlet.java
1 PackageServlets;2 3 Importjava.io.IOException;4 5 ImportJavax.servlet.RequestDispatcher;6 Importjavax.servlet.ServletException;7 ImportJavax.servlet.annotation.WebServlet;8 ImportJavax.servlet.http.HttpServlet;9 Importjavax.servlet.http.HttpServletRequest;Ten ImportJavax.servlet.http.HttpServletResponse; One A /** - * Servlet Implementation class ForwardServlet - */ the@WebServlet ("/forwardservlet") - Public classForwardServletextendsHttpServlet { - Private Static Final LongSerialversionuid = 1L; - + protected voidDoget (HttpServletRequest request, httpservletresponse response)throwsservletexception, IOException { -System.out.println ("ForwardServlet doget"); + //Request Forwarding AString path= "Nextservlet"; atRequestDispatcher requestdispatcher=request.getrequestdispatcher ("/" +path); - Requestdispatcher.forward (request, response); - } - -}4.nextservlet.java
1 PackageServlets;2 3 Importjava.io.IOException;4 Importjavax.servlet.ServletException;5 ImportJavax.servlet.annotation.WebServlet;6 ImportJavax.servlet.http.HttpServlet;7 Importjavax.servlet.http.HttpServletRequest;8 ImportJavax.servlet.http.HttpServletResponse;9 Ten /** One * Servlet Implementation class Nextservlet A */ -@WebServlet ("/nextservlet") - Public classNextservletextendsHttpServlet { the Private Static Final LongSerialversionuid = 1L; - - protected voidDoget (HttpServletRequest request, httpservletresponse response)throwsservletexception, IOException { -System.out.println ("Nextservlet doget"); + } -}5.redirectservlet.java
1 PackageServlets;2 3 Importjava.io.IOException;4 Importjavax.servlet.ServletException;5 ImportJavax.servlet.annotation.WebServlet;6 ImportJavax.servlet.http.HttpServlet;7 Importjavax.servlet.http.HttpServletRequest;8 ImportJavax.servlet.http.HttpServletResponse;9 Ten /** One * Servlet Implementation class Redirectservlet A */ -@WebServlet ("/redirectservlet") - Public classRedirectservletextendsHttpServlet { the Private Static Final LongSerialversionuid = 1L; - - protected voidDoget (HttpServletRequest request, httpservletresponse response)throwsservletexception, IOException { -System.out.println ("Redirectservlet doget"); + - // redirect +String path= "Nextservlet"; A response.sendredirect (path); at } -}6. Effects
Click the link individually.
JSP learning two (request forwarding and redirection)
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