Specify the order in which configuration files and classes are loaded in Java

The problem you want to solve

--When executing WAR, if there are multiple configuration files with the same name on the classpath for some reason, you want to specify the order in which they are loaded. --Environment assumes WebSphere Liberty, Java 8 --There are three simple ways to include the configuration file and class in the classpath. I want to check these three priorities --Include in WAR file --Include in JAR file and place in WEB-INF / lib of WAR file --Place outside WAR (specify in <library> in Liberty's server.xml)

Result from the research

The order was as follows. Since 1 and 2 are difficult to set freely due to the packaging method and the arrangement of environment-dependent files, if you want to specify the loading order in detail, place the JAR outside the WAR, and then <library> It seems good to specify the order in detail in .

Include in WAR file
Include it in the JAR file and place it in the WAR file WEB-INF / lib
Place outside of WAR (specify in <library> in Liberty's server.xml)

Specifically, it has such a shape. The order of specifying the child elements of <library> is the order of class loading. When not only <file> but also <folder> is specified, the order of XML elements is the order of class loading.

<library id="mydir">
  <file name="/mydir/foo1.jar"/>
  <file name="/mydir/foo2.jar"/>
</library>

<webApplication location="/dir/bar.war">
  <classloader privateLibraryRef="mydir"/>
</webApplication>

What I didn't understand

It seems that the same setting can be made by specifying Class-Path of MANIFEST.MF, but if it is specified by Class-Path of MANIFEST.MF included in WAR, it will not be the target of class loading for some reason. It was like.