Introduction to the Forward and sendRedirect methods of JSP

Response. sendRedirect is two different requests that are redirected on the client, and the browser displays the name of the page after the jump. Because it redirects from the client to the second page.

When forward is used, because only one request is sent, the property setAttribute set for the request can still be stored on the next page.

When sendRedirect is used, the request attribute cannot be obtained next time because two request requests are sent. However, you can rewrite the URL.

The content is passed in.

The following is an example:

Tian. jsp
<% Request. setAttribute ("river", "redwater ");
Request. setAttribute ("country", "daguaiwan ");
%>
<Jsp: forward page = "fengshan. jsp"/>
Donglan. jsp
<% Request. setAttribute ("river", "redwater ");
Request. setAttribute ("country", "daguaiwan ");
%>
<A href = "fengshan. jsp"> fengshan </a>
  Bama. jsp
<% Request. setAttribute ("river", "redwater ");
Request. setAttribute ("country", "daguaiwan ");
Response. sendRedirect ("fengshan. jsp ");
%>
Fengshan. jsp
<% = Request. getAttribute ("river") %> <br/>
<% = Request. getAttribute ("country") %>
 

   
 

    
  
Http: // localhost: 8080/ForwardRedirect/tiane. jsp:
    
  
Redwater
    
  
Daguaiwan
    
  

    
  
Http: // localhost: 8080/ForwardRedirect/donglan. jsp:
    
  
Null
    
  
Null
    
  

    
  
Http: // localhost: 8080/ForwardRedirect/bama. jsp:
    
  
Null
    
  
Null
   
 

Result Analysis: tiane. jsp jumps to fengshan through forward. jsp, the two pages use the same request, so fengshan. jsp can receive tiane. attributes set by jsp through request. And donglan. jsp sends another request through href, bama. jsp jumps through sendRedirect and uses another request. Therefore, fengshan. jsp cannot receive the attributes set by request on these two pages. Jump between Jsp and Servlet: jump from Jsp to Servlet can be used or response. sendRedirect (URL), the difference between them has been described above. Jump from Servlet to Jsp: getRequestDispatcher's forward (request, response) method. Here we only send a request, and you can accept the attributes set by the request on the next page. 2. response. sendRedirect (URL). Two requests are sent here. The attributes set by the request cannot be accepted on the next page.

Example: servlettiane. jsp

   
 

    
  
<%request.setAttribute("river","redwater");   
    
  
    request.setAttribute("country","daguaiwan");   
    
  
%>   
    
  
<jsp:forward page="/tiane" />   
    
  
 
    
  
servletbama.jsp      
    
  
<%request.setAttribute("river","redwater");   
    
  
    request.setAttribute("country","daguaiwan");   
    
  
    response.sendRedirect("/ForwardRedirect/tiane");   
    
  
%>  
   
 

Tiane. java

   
 

    
  
public class Tiane extends HttpServlet {   
    
  
 
    
  
  public void doGet(HttpServletRequest request, HttpServletResponse response)   
    
  
      throws ServletException, IOException {   
    
  
//    response.sendRedirect("/ForwardRedirect/fengshan.jsp");   
    
  
    this.getServletConfig().getServletContext()   
    
  
            .getRequestDispatcher("/fengshan.jsp").forward(request, response);   
    
  
  }   
    
  
 
    
  
  public void doPost(HttpServletRequest request, HttpServletResponse response)   
    
  
      throws ServletException, IOException {   
    
  
    doGet(request, response);   
    
  
  }      
    
  
}  
   
 

Configure servlet in web. xml:

   
 

    
  
<servlet>   
    
  
  <servlet-name>tiane</servlet-name>   
    
  
  <servlet-class>com.dvnchina.test.Tiane</servlet-class>   
    
  
  </servlet>   
    
  
  <servlet-mapping>   
    
  
  <servlet-name>tiane</servlet-name>   
    
  
  <url-pattern>/tiane</url-pattern>   
    
  
</servlet-mapping>  
   
 

I will not analyze the specific results, which is similar to the first example. See the attachment for the code.

1. Analysis on CGI supported by jsp http Server
2. Use JSP pages to generate PDF reports
3. Step for customizing JSP labels
4. Detailed test of JSP containers
5. Describes the following features of jsp http Server