本文共 2917 字，大约阅读时间需要 9 分钟。

???????Web??????????????????????????????????????????????????

???

????????????????????????????????????????Web?????Tomcat??????????????????302??????????????????????302?????????????????????????

??????

??????

????????????????????

• login.html??????????????????????
• target.html????????????

login.html:
   
   
    
    
    
    
    
    
   

• LoginServlet.java????????????????

package com.qfedu.a_servlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        System.out.println(username + " " + password); // ??????
        // ?????
        response.sendRedirect("target.html");
    }
}

??

??????????????????????????????????????????servlet??????????????????

?????

????????????

• TestServlet1.java??????????????

package com.qfedu.a_servlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/TestServlet1")
public class TestServlet1 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("????1"); // ????
        // ??????
        request.setAttribute("name", "??");
        request.getRequestDispatcher("TestServlet2").forward(request, response);
    }
}

• TestServlet2.java???????????

package com.qfedu.a_servlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
@WebServlet("/TestServlet2")
public class TestServlet2 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("????2"); // ????
        // ???????
        Object name = request.getAttribute("name");
        response.getWriter().append(name.toString());
    }
}

??

????????Web?????????????????????????????????????????????????????????????????????????????????????????????????