关于重定向页面和请求转发页面的区别

重定向页面resp.sendRedirect(forword)会有2次响应，重定向的页面无法通过req.getParameter("username")获取到表单信息

请求转发页面只进行一次响应可以获取响应表单元素req.getParameter("username")

forword="/xxx.jsp";

RequestDispatcher rd= req.getRequestDispatcher(forword);

rd.forward(req, resp);

1 package com.iwb.servlet; 2 3 import java.io.IOException; 4 5 import javax.servlet.RequestDispatcher; 6 import javax.servlet.ServletException; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse;10 11 public class LoginServlet extends HttpServlet {12 13/**14* 15*/16private static final long serialVersionUID = 1L;17 18/*@Override19protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {20 // TODO Auto-generated method stub21 String userName=req.getParameter("uname");22 String password=req.getParameter("upwd");23 24 System.out.println("用户名=>"+userName);25 System.out.println("密码=>"+password);26}*/27 28@Override29protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {30 // TODO Auto-generated method stub31 System.out.println("=======进入doGet方法========");32 doPost(req,resp);33}34 35@Override36protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {37 // TODO Auto-generated method stub38 System.out.println("=======进入doPost方法========");39 String userName=req.getParameter("uname");40 String password=req.getParameter("upwd");41 42 System.out.println("用户名=>"+userName);43 System.out.println("密码=>"+password);44 String forword=null;45 if(userName.equals("iwb") && password.equals("iwb")){46 //请求转发47 forword="/success.jsp";48 RequestDispatcher rd= req.getRequestDispatcher(forword);49 rd.forward(req, resp);50 //重定向51 //resp.sendRedirect(req.getContextPath()+"/success.jsp");52 }else{53 //请求转发54 forword="/error.jsp";55 RequestDispatcher rd= req.getRequestDispatcher(forword);56 rd.forward(req, resp);57 //重定向58 //resp.sendRedirect(req.getContextPath()+"/error.jsp");59 }60}61 62 }

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