Load properties file in JAR

Question

I m having trouble when one of the jars that my web app depends on tries to load a properties file from within the jar   Here is the code in the jar   static       Properties props   new Properties        try                props load ClassLoader getSystemResourceAsStream  someProps properties           catch  IOException e                 e printStackTrace              someProperty   props getProperty  someKey        The properties file is in my  src main resources  directory of the Maven project   When I run this code from my junit test in Eclipse  it executes just fine   When the project is built with Maven into a jar  and included as a dependency in my web app  it fails to locate the properties file   I know that the properties file is at the base directory of the depended on jar  I don t know how to fix this

User · Answer

For the record  this is documented in How do I add resources to my JAR   illustrated for unit tests but the same applies for a  regular  resource       To add resources to the classpath for   your unit tests  you follow the same   pattern as you do for adding resources   to the JAR except the directory you   place resources in is     basedir  src test resources  At   this point you would have a project   directory structure that would look   like the following   my-app  -- pom xml  -- src      -- main          -- java              -- com                  -- mycompany                      -- app                          -- App java          -- resources              -- META-INF                  -- application properties      -- test          -- java              -- com                  -- mycompany                      -- app                          -- AppTest java          -- resources              -- test properties       In a unit test you could use a simple   snippet of code like the following to   access the resource required for   testing           Retrieve resource InputStream is   getClass   getResourceAsStream   test properties         Do something with the resource

User · Answer

The problem is that you are using getSystemResourceAsStream  Use simply getResourceAsStream  System resources load from the system classloader  which is almost certainly not the class loader that your jar is loaded into when run as a webapp    It works in Eclipse because when launching an application  the system classloader is configured with your jar as part of its classpath   E g  java -jar my jar will load my jar in the system class loader   This is not the case with web applications - application servers use complex class loading to isolate webapplications from each other and from the internals of the application server  For example  see the tomcat classloader how-to  and the diagram of the classloader hierarchy used   EDIT  Normally  you would call getClass   getResourceAsStream   to retrieve a resource in the classpath  but as you are fetching the resource in a static initializer  you will need to explicitly name a class that is in the classloader you want to load from  The simplest approach is to use the class containing the static initializer  e g    public  class MyClass     static                 props load MyClass class getResourceAsStream   someProps properties

[java] Load properties file in JAR?

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