Develop Reference

Take logback.xml to outside of the jar

I am using logback with slf4j in my Maven Java project. Currently logback config file (logback.xml) is in src -> main -> resources folder. And it is working fine.
My issue is, I need to give my client the ability to configure logging as he prefers. For that logback.xml should be outside the jar when I build it. But as xml is inside src folder it is inside the jar and no one can change it after build.
How to achieve this?

Specifying the location of the default configuration file as a system property
You may specify the location of the default configuration file with a system property named "logback.configurationFile". The value of this property can be a URL, a resource on the class path or a path to a file external to the application.
java -Dlogback.configurationFile=/path/to/config.xml -jar myapp.jar
From offcial docs

Logback config file location can be specified in application.properties or application.yml.
application.yml
logging:
config: logback-spring.xml
This allows you to place jar and log-back.xml at the same folder.
Please note that logback-spring.xml file in your project folder should not be included in your jar. This can be achieved setting on build.gradle or pom.xml.
build.gradle
bootJar {
archiveName 'your-project.jar'
exclude("*.xml")
}

The logback.xml file needs to be on the classpath, but it doesn't need to be inside any specific jar. The details of how you want to do this depend on the exact deployment mechanism that's being used: How does whatever's starting this application set the classpath? Whatever that mechanism is, you should be able to configure it to include wherever you're putting the logback.xml file, and then just don't include in in the src/main/resources to be embedded in the jar file.
Depending on the complexity of what you're going for, you may find the maven-assembly-plugin useful for creating your distribution of dependencies.

Using Scala SBT (1.2.1) on Windows:
Batch file:
#cd %~dp0
#set JAVA_OPTS=-Dlogback.configurationFile=logback.xml
#sbt clean run
worked for me (strange ...)

log4j xml configuration file outside the classpath

I am having my log4j xml configuration file outside of the project. I am loading the xml configuration file by using absolute path as
DOMConfigurator.configure("D:/E-Signature/ESignature logs/log4j_Properties_Xml/log4j-properties.xml");. Since I am going to convert my project to executable jar I have kept it outside of the project.
Is there any other efficient way to handle this without giving the absolute path.

If your project is a maven project, you can put the log4j.properties in the src/main/resources folder so you don't need to give the absolute path and if it is a simple java project put it in the src folder it will work.

Trying to reference a folder with my .properties and log4j files in IntelliJ

I don't want to put my .properties and log4j files in my /resources folder in my spring MVC appication because these will get put into the jar at compile time, and I want to be able to edit these files on my server when I deploy my application.
So I created a folder and dropped my log4j, *.properties files, and my spring-context.xml file in it.
I have a maven multi project, and my folders look like:
/myapp-persists
/myapp-web
/src/main/conf
The /src/main/conf has my property files, so in IntelliJ I went to the myapp-web module and added a 'jar or directories' dependancy, pointed to that folder and chose 'classes'.
It didn't work, my files were not picked up and starting the server resulted in a crash, the property files were not detected.
What am I doing wrong here?
It seems me doing this via intelliJ is going to cause my maven builds to fail then right? I really don't want to create a separate maven project for this.

You can just use the context menu on /src/main/conf and choose Directory : Add as Source. In the preferences you should set keep source folders in the maven settings (not really sure about the naming of the menu/settings - no idea at hand, sorry). The jar dependency is not needed.

What is the Maven idiom for accessing configuration files?

For example suppose I'm using the standard project structure and have
src/main/config/config.xml
To access this I presume
new File("src/main/config/config.xml");
would be incorrect

There is no "Maven Idiom" for accessing configuration files. Maven is a build platform, not an execution platform. So the conventions for accessing configuration files that apply are really just the conventions of the Java platform that you are using; e.g.
the plain J2SE way of doing it, or
the J2EE and/or webapp way of doing it, or
the J2ME way of doing it, or
...
Maven only comes into the picture because you (presumably) have resource files in your project / version control that need to be included in the JAR or WAR or whatever artifacts that you are building. To get this to work in Maven, you simply need to understand how Maven copies non-Java files into the artifacts.
In the simple (JAR) case, the default behavior is to copy anything in src/main/resources/ into the JAR, with the same relative name; e.g. src/main/resource/foo/bar.xml becomes /foo/bar.xml in the JAR file.
For WAR files, the default is to copy anything src/main/webapp to into the WAR file. So if you wanted a file to be accessible in the webapp as a classpath resource with the name /foo/bar.xml you would put it in src/main/webapp/WEB-INF/classes/foo/bar.xml. (I'm assuming that you know how webapp classpaths work ... or that this isn't your use-case.)

A config file is just a resource on your classpath like any other, so use:
URL resource = getClass().getResource("config.xml");
You'll need to do the usual Use as Source Folder on your src/main/config folder for this to work in Eclipse with m2e.

I think config files should be in src/main/resources by default.

How to access a XML file in a maven project so it stays available when packaged

I currently started working on a maven web-app project that needs to be launched with the jetty:run-exploded goal for development/debugging in eclipse.
Now, I have an XML file which contents I need to access at runtime. My problem is: where to put the file so that the code that does the reading works both in "exploded" and packaged (i.e. in the WAR) mode?
Putting the file in src/main/java (so as to be in the classpath) won't cut it since maven filters out all non-java files on packaging.
When the file is in src/main/resources, one mean would be to figure out the root path of the project (during eclipse development) and look into that directory - but this won't be the case anymore when the project will be packaged.
Of course I could go into writing code that tries to read the file from both locations, but this seems rather cumbersome. Any suggestions?

Files in src/main/resources are copied to the target/classes directory and are available on the class path. Just read them from the class path. As explained in How do I add resources to my JAR? from the maven documentation (with a test resource here):
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
...

In such case I put the file under src/main/resources directory and use Spring's ClassPathResource. This way the file is accessible in IDE, during Maven build process and in runtime.