Tomcat Server with ability to upload jar-files and relative paths

Question

I got a Tomcat Server running. And it's possible to upload jar-files within the web interface. Now the server is able to invoke methods of the uploaded jar-file. The problem is, that I got some relative paths to some files in my jar-file. If I run my jar-file locally it's no problem but on the server the paths don't fit anymore.

The place where the jar file is uploaded is given through this:

arg0.getServletContext().getRealPath(File.separator) + "WEB-INF" + File.separatorChar + "lib" + File.separatorChar;

From my jar-file I don't have the option to get the Servlet Context because it's an closed environment within the jar-file.

Any Idea how I can access the files?

Tanks

Answer 1

You should not treat resources within a Java application archive (JAR, WAR, EAR, whatevAR) like disk file system resources. You should treat them like classpath resources.

Simply put, this is wrong as it depends on the "current working directory" when the JVM was started and you have no control over that from inside your Java application:

InputStream resource = new FileInputStream("file.ext"); // Relative to CWD.

One of those is right, depending on whether you'd like to allow users to override the JAR-bundled resource by placing another resource on exactly the same FQN outside the JAR on a place having higher classloading precedence:

InputStream resource = getClass().getResourceAsStream("file.ext"); // Relative to class' package.

InputStream resource = Thread.currentThread().getContextClassLoader().getResourceAsStream("file.ext"); // Relative to classpath root.

See also:

• getResourceAsStream() vs FileInputStream
• Where to place and how to read configuration resource files in servlet based application?