Servlet不执行response.sendRedirect（addressPath）; ，但会执行没有路径的response.sendRedirect（）

Question

Consider the following hierarchy :

When I send redirect like this :

    response.sendRedirect("error404.jsp");    // no path here !!!

I reach the page error404.jsp .

But when I use a path :

    String addressPath = "/WEB-INF/results/admin/adminPage.jsp";
    response.sendRedirect(addressPath);   // with path !!!

I get 404 :

HTTP Status 404 -

type Status report

message

description The requested resource is not available.

Apache Tomcat/7.0.50

What am I doing wrong here ?

Much appreciated !

Answer 1

See the javadoc

This method can accept relative URLs;the servlet container must convert the relative URL to an absolute URL before sending the response to the client. If the location is relative without a leading '/' the container interprets it as relative to the current request URI. If the location is relative with a leading '/' the container interprets it as relative to the servlet container root. If the location is relative with two leading '/' the container interprets it as a network-path reference (see RFC 3986: Uniform Resource Identifier (URI): Generic Syntax, section 4.2 "Relative Reference").

Note that the argument is not a path within the servlet context like a RequestDispatcher would use, it as a URL used in the Location header of the 302 response.

So this

String addressPath = "/WEB-INF/results/admin/adminPage.jsp";
response.sendRedirect(addressPath);   // with path !!!

will be transformed into a 302 response with the header

Location: http://whateverhost.com/WEB-INF/results/admin/adminPage.jsp

which you don't have a handler for, so 404.

On the other hand, this

response.sendRedirect("error404.jsp");    // no path here !!!

becomes

Location: http://whateverhost.com/context-path/error404.jsp

Since error404.jsp is outside WEB-INF , it is accessible and therefore rendered by the JSP servlet and returned as a response.

Answer 2

Because stuff under WEB-INF is not accessible to the client. Don't put your JSPs under WEB-INF if you want them to be accessible.

Alternatively, to make anything under WEB-INF accessible to the client, you would have to map it to a URL in web.xml:

  <servlet>
    <servlet-name>adminPage</servlet-name> 
    <jsp-file>/WEB-INF/results/admin/adminPage.jsp</jsp-file>
  </servlet>
  <servlet-mapping>
    <servlet-name>adminPage</servlet-name>
    <url-pattern>/adminPage/*</url-pattern>
</servlet-mapping> 

Then use the url-pattern you mapped:

response.sendRedirect("./adminPage/");

Which is rather pointless. You could achieve basically the same thing with your JSP outside of WEB-INF and using a URL Rewrite Filter. In short, you probably have no real reason to put your JSPs under WEB-INF.