在实现之前我们首先应该了解请求转发和请求重定向的概念和区别:https://www.cnblogs.com/haimishasha/p/5952129.html
在Servlet中,我们是通过ReqDispatcher对象来实现请求转发,Servlet把请求转发给Servlet、HTML、JSP或其它信息资源,由第2个信息资源响应该请求,两个信息资源共享同一个request对象。
有两种方式可以获取这个对象:
//1.通过ServletContent.getReqDisPathcer()获取ReqDisPathcer对象,再调用该对象的forward()实现请求转发 RequestDispatcher requestDispatcher= this.getServletContext().getRequestDispatcher("/test.jsp"); requestDispatcher.forward(request,response); //2.通过Request.getDisPatcher()获取ReqDisPatcher对象,再调用该对象的forward()实现请求转发 RequestDispatcher requestDispatcher=request.getRequestDispatcher("/test.jsp").forward(request,response);
下面我们可以来看一个Demo:
在TestReqDispatcher Servlet中将请求转发至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="今天天气很好"; request.setAttribute("data",data); //1.通过ServletContent.getReqDisPathcer()获取ReqDisPathcer对象,再调用该对象的forward()实现请求转发 RequestDispatcher requestDispatcher= this.getServletContext().getRequestDispatcher("/test.jsp"); requestDispatcher.forward(request,response); //2.通过Request.getDisPatcher()获取ReqDisPatcher对象,再调用该对象的forward()实现请求转发 //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表达式取出data: <h2>${data}</h2> </body> </html>
好了,我们看一下在浏览器输出的结果: