mapping servlet to serve my requests

Question

I would like to map a servlet to serve the requests that includes 'app' and ends with *.html in the following way

<url-pattern>/app/*.html</url-pattern>

but on running the application it gives me an error

java.lang.IllegalArgumentException: Invalid <url-pattern> 
/app/*.html in servlet mapping

please help me to map that. And please provide me the links where I can learn about these url mapping rule and conventions.

score 11 · Accepted Answer · edited May 23 '17 at 11:46

This is indeed invalid. The wildcard has to be the first or the last character to indicate a suffix or prefix pattern respectively.

<url-pattern>*.html</url-pattern>

or

<url-pattern>/app/*</url-pattern>

This is all clearly specified in Section 12.2 of Servlet API specification. Here's an extract of relevance:

12.2 Specification of Mappings

In the Web application deployment descriptor, the following syntax is used to define mappings:

A string beginning with a ‘/’ character and ending with a ‘/*’ suffix is used for path mapping.

A string beginning with a ‘*.’ prefix is used as an extension mapping.

The empty string ("") is a special URL pattern that exactly maps to the application's context root, i.e., requests of the form http://host:port/<contextroot>/. In this case the path info is ’/’ and the servlet path and context path is empty string (““).

A string containing only the ’/’ character indicates the "default" servlet of the application. In this case the servlet path is the request URI minus the context path and the path info is null.

All other strings are used for exact matches only.

To fix this, you have 2 options:

Use the /app/* pattern and do not put non-HTML files in /app. Put them elsewhere.

Use a different prefix pattern like /controller/* and create a Filter which is mapped on /app/* and does the following in doFilter() method:

String uri = ((HttpServletRequest) request).getRequestURI();
if (uri.endsWith(".html")) {
    request.getRequestDispatcher("/controller" + uri).forward(request, response);
} else {
    chain.doFilter(request, response);
}

mapping servlet to serve my requests

2 Answers2

12.2 Specification of Mappings

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