Accessing Resources in the WAR/WEB-INF Directory with ServletContext

Introduction:

Java web applications often store essential resources within the WAR/WEB-INF directory. To access these resources, developers can leverage the ServletContext API.

Question:

How can you create the correct path to a resource located in the WAR/WEB-INF folder, such as "/war/WEB-INF/test/foo.txt"?

Answer:

There are two primary methods for constructing the path to resources in the WAR/WEB-INF directory using ServletContext:

1. getRealPath() Method:

If the WAR file has been expanded into a set of files, you can use the getRealPath() method:

ServletContext context = getContext();
String fullPath = context.getRealPath("/WEB-INF/test/foo.txt");

This will return the complete system path to the resource.

2. getResource() or getResourceAsStream() Methods:

These methods can be used regardless of whether the WAR file is expanded or not:

ServletContext context = getContext();
URL resourceUrl = context.getResource("/WEB-INF/test/foo.txt"); // for URL
InputStream resourceContent = context.getResourceAsStream("/WEB-INF/test/foo.txt"); // for input stream

Additional Notes:

• The getContext() method mentioned in the sample code is application-specific. In JSP pages, it is available as "context," while in servlets, it is obtained from the ServletConfig during initialization.
• The getRealPath() method may not work if the Servlet Container does not extract the WAR file.
• The getResource() and getResourceAsStream() methods are reliable and work in all deployment scenarios.