Request对象实现转发

最新推荐文章于 2024-07-25 20:05:43 发布

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本文通过两个Servlet示例演示了Java Web应用中请求转发的过程及特点。重点介绍了如何使用`RequestDispatcher`接口的`forward`方法实现请求转发，并展示了转发前后响应正文的变化。

ForwardDemo1.java文件：

package com.neu;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//转发：源

//转发前后，源输出的任何响应正文无效
public class ForwardDemo1 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        System.out.println("转发前");
        response.getWriter().write("forward before");//转发前会清空响应对象中的正文内容
        request.getRequestDispatcher("/servlet/ForwardDemo2").forward(request, response);//转发
        System.out.println("转发后");
        response.getWriter().write("forward after");
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}

ForwardDemo2.java文件：

package com.neu;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
//转发：目标
public class ForwardDemo2 extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.getWriter().write("222222");//响应结束
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }
}