標籤：insert ima 請求 code doget 區別 XML ring splay
一：
1.介紹知識點
1). 本質區別: 請求的轉寄只發出了一次請求, 而重新導向則發出了兩次請求.
具體:
①. 請求的轉寄: 地址欄是初次發出請求的地址.
請求的重新導向: 地址欄不再是初次發出的請求地址. 地址欄為最後響應的那個地址
②. 請求轉寄: 在最終的 Servlet 中, request 對象和中轉的那個 request 是同一個對象.
請求的重新導向: 在最終的 Servlet 中, request 對象和中轉的那個 request 不是同一個對象.
③. 請求的轉寄: 只能轉寄給當前 WEB 應用的的資源
請求的重新導向: 可以重新導向到任何資源.
④. 請求的轉寄: / 代表的是當前 WEB 應用的根目錄
請求的重新導向: / 代表的是當前 WEB 網站的根目錄.
二：程式
1.web.xml(關於配置使用註解了)
1 <?xml version="1.0" encoding="UTF-8"?>2 <web-app xmlns: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檔案（兩種連結代表兩種知識點）
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 <!-- 請求轉寄 -->11 <a href="forwardServlet">Forward</a>12 13 <br><br>14 15 <!-- 重新導向 -->16 <a href="redirectServlet">RedirectServlet</a>17 </body>18 </html>
3.ForwardServlet.java
1 package Servlets; 2 3 import java.io.IOException; 4 5 import javax.servlet.RequestDispatcher; 6 import javax.servlet.ServletException; 7 import javax.servlet.annotation.WebServlet; 8 import javax.servlet.http.HttpServlet; 9 import javax.servlet.http.HttpServletRequest;10 import javax.servlet.http.HttpServletResponse;11 12 /**13 * Servlet implementation class ForwardServlet14 */15 @WebServlet("/forwardServlet")16 public class ForwardServlet extends HttpServlet {17 private static final long serialVersionUID = 1L;18 19 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {20 System.out.println("ForwardServlet doGet");21 //請求轉寄22 String path="nextServlet";23 RequestDispatcher requestDispatcher=request.getRequestDispatcher("/"+path);24 requestDispatcher.forward(request, response);25 }26 27 }
4.NextServlet.java
1 package Servlets; 2 3 import java.io.IOException; 4 import javax.servlet.ServletException; 5 import javax.servlet.annotation.WebServlet; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 /**11 * Servlet implementation class NextServlet12 */13 @WebServlet("/nextServlet")14 public class NextServlet extends HttpServlet {15 private static final long serialVersionUID = 1L;16 17 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {18 System.out.println("NextServlet doGet");19 }20 }
5.RedirectServlet.java
1 package Servlets; 2 3 import java.io.IOException; 4 import javax.servlet.ServletException; 5 import javax.servlet.annotation.WebServlet; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 10 /**11 * Servlet implementation class RedirectServlet12 */13 @WebServlet("/redirectServlet")14 public class RedirectServlet extends HttpServlet {15 private static final long serialVersionUID = 1L;16 17 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {18 System.out.println("RedirectServlet doGet");19 20 //重新導向21 String path="nextServlet";22 response.sendRedirect(path);23 }24 }
6.效果
分別點擊一次連結。
JSP的學習二（請求轉寄與 重新導向）
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