Java Web中请求转发和请求包含

时间：2022-01-15 13:36:54

1、都是在一个请求中跨越多个Servlet

2、多个Servlet在一个请求中，他们共享request对象。就是在AServle中setAttribute（）保存数据在BServlet中由getAttribute（）取出数据

3、在AServlet转发到BServlet，那么整个请求都是由BServlet来完成，AServlet不再插手

4、AServlet 包含BServlet，那么两个Servlet共同完成请求

5、请求转发和请求包含都需要使用一个对象RequestDispatcher。

AServlet.java

package cn.edu.aynu.rjxy.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class AServlet extends HttpServlet {

    /*

     * 请求转发

     * */

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        //设置响应头

         response.setContentType("text/html;charset=utf-8");

        response.getWriter().print("AServlet...");

        request.setAttribute("name", "张三");

        //获得RequestDispatcher对象

        RequestDispatcher rd = request.getRequestDispatcher("/BServlet");

        //将request对象和response对象传递给BServlet

        rd.forward(request, response);

    }

}

BServlet.java

package cn.edu.aynu.rjxy.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class BServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        String name = (String) request.getAttribute("name");

        response.getWriter().print("BServlet为您服务...");

        response.getWriter().print("name="+name);

    }

}

CServlet.java

package cn.edu.aynu.rjxy.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class CServlet extends HttpServlet {

    /*

     * 请求包含

     * */

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        //设置响应头

         response.setContentType("text/html;charset=utf-8");

        response.getWriter().print("AServlet为您服务...");

        RequestDispatcher rd = request.getRequestDispatcher("/DServlet");

        rd.include(request, response);

    }

}

DSevler.java

package cn.edu.aynu.rjxy.servlet;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class DServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        response.getWriter().print("DServlet为您服务...");

    }

}

1、请求转发是一个请求，而重定向是两个请求

2、请求转发后浏览器地址栏不会发生变化重定向会发生变化

3、请求转发的目标只能在本项目中的资源，重定向的目标可以是其他应用

4、请求转发对Aservlet和Bservlet的请求方法是相同的，就是要么都是get，要么都是post。因为他们是同一个请求

5、请求转发可以在多个Servlet*享request的数据，而重定向不行。

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