RequestDispatche转发（forward）和包含（include）的区别

本文链接：https://blog.youkuaiyun.com/liuzhenghui666666/article/details/94638374

本文详细探讨了Servlet中RequestDispatcher的forward和include方法的区别。forward是服务器内部跳转，请求处理完成后用户无法感知；include则是将一个请求的结果嵌入到另一个响应中，两个资源可以共享同一个请求环境。forward只能转发一次，而include可以多次包含。理解这两个概念对于优化Web应用程序的性能和结构至关重要。

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import javax.servlet.RequestDispatcher;
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("/dispatcher3")
public class DispatcherServlet3 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //这儿的path有两种写法，第一种是不以/开头

        System.out.println("dispatcher3");
        response.getWriter().println("dispatcher3");
        //以/开头时，注意：如果执行主体是浏览器的时候，浏览器不知道当前应用的应用名是什么，所以要加
                        //如果是服务器，那么服务器知道当前应用名，则必须省略该应用名
        RequestDispatcher dispatcher = request.getRequestDispatcher("/dispatcher4");
//        dispatcher.forward(request,response);//转发  打印dispatcher4(会覆盖)
        dispatcher.include(request,response);//包含  打印dispatcher3（不会覆盖）
                                                     // dispatcher4
    }
}
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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("/dispatcher4")
public class DispatcherServlet4 extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        System.out.println("dispatcher4");
        response.getWriter().println("dispatcher4");
    }
}