JavaWeb_请求转发

原文链接： http://www.cnblogs.com/yangHS/p/10985219.html

请求的转发和重定向：

1）本质区别：请求的转发只发出一次请求，而重定向则发出来两次请求。

具体：

①请求的转发：地址栏是初次发出请求的地址

请求的重定向：地址栏不再是初次发出的请求地址，地址栏为最后响应的那个地址

②请求转发：在最终的Servlet中，request对象和中转的那个request是同一个对象

请求的重定向：在最终的Servlet中，request对象和中转的那个request不是同一个对象

(3)请求的转发：只能转发给当前WEB应用的资源

　 请求的重定向：可以重定向到任何资源。

④请求转发：/ 代表的是当前WEB应用的根目录

　请求重定向：/ 代表的是当前WEB站点的根目录

JSP

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<a href="ForwardServlet">ForwardServlet</a>

<br>

<a href="RedirectServlet">RedirectServlet</a>
</body>
</html>

Servlet

public class ForwardServlet 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("ForwardServlet's doGet");

        /**
         * 请求的转发
         * 1.调用HttpServletRequest的getRequestDispatcher()方法获取RequestDispatcher对象
         * 调用getRequestDispatcher()需要传入要转发的地址
         */
        String path = "/TestServlet";

        RequestDispatcher requestDispatcher = request.getRequestDispatcher(path);
         /**
         * 2.调用HttpServletRequest的forward(request,response)进行请求的转发
         */
         requestDispatcher.forward(request,response);

    }
public class TestServlet 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("TestServlet's doGet");
    }
}


@WebServlet(name = "RedirectServlet")
public class RedirectServlet 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("RedirectServlet's doGet");
        //执行请求的重定向，直接调用response，sendRedirect(path)方法
        //path为要重定向的地址
        String path = "TestServlet";
        response.sendRedirect(path);
    }
}

转载于:https://www.cnblogs.com/yangHS/p/10985219.html

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