在實現之前我們首先應該了解請求轉發和請求重定向的概念和區別：https://www.cnblogs.com/haimishasha/p/5952129.html
在Servlet中，我們是通過ReqDispatcher對象來實現請求轉發，Servlet把請求轉發給Servlet、HTML、JSP或其它信息資源，由第2個信息資源響應該請求，兩個信息資源共享同一個request對象。
有兩種方式可以獲取這個對象：
//1.通過ServletContent.getReqDisPathcer()獲取ReqDisPathcer對象，再調用該對象的forward()實現請求轉發 RequestDispatcher requestDispatcher= this.getServletContext().getRequestDispatcher("/test.jsp"); requestDispatcher.forward(request,response); //2.通過Request.getDisPatcher()獲取ReqDisPatcher對象，再調用該對象的forward()實現請求轉發 RequestDispatcher requestDispatcher=request.getRequestDispatcher("/test.jsp").forward(request,response);
下面我們可以來看一個Demo：
在TestReqDispatcher Servlet中將請求轉發至test.jsp
package com.java.controller; import javax.servlet.RequestDispatcher; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; public class TestReqDispatcher extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String data="今天天氣很好"; request.setAttribute("data",data); //1.通過ServletContent.getReqDisPathcer()獲取ReqDisPathcer對象，再調用該對象的forward()實現請求轉發 RequestDispatcher requestDispatcher= this.getServletContext().getRequestDispatcher("/test.jsp"); requestDispatcher.forward(request,response); //2.通過Request.getDisPatcher()獲取ReqDisPatcher對象，再調用該對象的forward()實現請求轉發 //RequestDispatcher requestDispatcher=request.getRequestDispatcher("/test.jsp").forward(request,response); } public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException { doGet(request,response); } }
test.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>大家好</title> </head> <body> 普通方式取出data： <h2><%= request.getAttribute("data")%></h2> EL表達式取出data： <h2>${data}</h2> </body> </html>
好了，我們看一下在瀏覽器輸出的結果：
