Question

How can I get the name of the current web app in Java EE?

I’m quite comfortable with stand-alone Java, but Java EE is new to me. I’m writing some custom code to plug in to a third-party Java EE reporting package. I have multiple instances deployed on the same Tomcat server, so I have something like:

C:\
+-- tomcat6
    +-- webapps
        +-- app1
        +-- app2

So when the user goes to, let’s say, http://example.com/app1/viewReport, I want to be able to get “app1”. (And not by parsing the URL, preferrably.)

Also, if there was a way to get the root of app1 (in this example, C:\tomcat6\webapps\app1), that would be great too.

Answer 1

1. Getting the "name"
   =====
   It’s called the context path. If your code is running within the web app request context, you can get it by calling HttpServletRequest#getContextPath().

2. Accessing the physical/real resource
   =====
   If you’re trying to access the contents of a file/resource in your webapp, you’re best of using one of:

• ServletContext#getResource(String)
• ServletContext#getResourceAsStream(String)

It is also possible get the physical path on disk of a file/resource, given the path relative to the web app, using ServletContext#getRealPath(String), but it’s not reliable (doesn’t always work if you deploy you webapp as a WAR, for instance).

3. Accessing class path resources
   =====
   Per your comment, you were trying to access a resource within the /WEB-INF/classes directory. Because WEB-INF/classes/* is where web application specific classes go, you can simply access it as if you were accessing any classpath resource in a Java SE application. Again, assuming your code runs within the context of the webapp, you can simply use the following:

• Class#getResource(String)
• Class#getResourceAsStream(String)

In your case, you’d probably want to use the latter, and then load the Properties file via Properties#load(InputStream).

Something along the lines of:

Properties props = new Properties();
props.load(getClass().getResourceAsStream("/reportCustom.properties"));