JavaWeb_请求转发

一时失言乱红尘 2021-12-15 08:15 336阅读 0赞

**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