How to get ContextPath in init() method of Servlet version 2.4

java servlets contextpath
Lama picture Lama · Dec 14, 2012 · Viewed 13.6k times · Source

I'm using version 2.4 of Servlet and I need to get the ContextPath through the init() method which is called on server start, so I don't have any Request object that could call getContextPath() and because the Servlet version I do not have getContextPath() method in the ServletContext either.

Is there a way to get this ContextPath() somehow ?

Answer

Ian Roberts picture Ian Roberts · Dec 14, 2012

One web application can be published at several different context paths, so the context path (singular) is only meaningful in the context of a particular request. Servlet 2.5 added getContextPath() to ServletContext, specified to return the "primary" context path for this web application, but there's no container-independent way to access this information in earlier spec versions.

There may be tricks that work for certain containers, for example on Tomcat the ServletContext.getResource() method returns URLs with a custom scheme, of the form jndi://hostname/context/.... Thus you may be able to use

ctx.getResource("/").getPath()

to get the context path on Tomcat (or possibly getResource("/WEB-INF/web.xml") and trim off the tail, as getResource() is specified to return null if you ask it for a file that does not exist). You will have to experiment with different containers to find similar tricks that work on those.

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