How to set build properties from a file in Maven POM?

Question

I need to read and filter a properties file from a location outside my project, say ${user.home}/my.properties. This properties file looks like this:

res.dir         


        

Answer 1

I think it would be better if you turned the properties file into a template file and take the properties from the pom.xml using maven resource filtering.

A simple setup might look like this

pom.xml

    4.0.0

    com.stackoverflow
    Q12082277
    1.0-SNAPSHOT

    ${project.artifactId}-${project.version}

    
        /default/stuff/here
        ${res.dir}
        ${resource.dir}/bin
        ${resource.dir}/config
    

    
    
    

    
        
            
                src/main/resources
                true
            
        
    

src/main/resources/app.properties

res.dir=${res.dir}
resource.dir=${resource.dir}
bin.dir=${bin.dir}
cfg.dir=${cfg.dir}

src/main/java/com/stackoverflow/Q12082277/App.java

package com.stackoverflow.Q12082277;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/**
 * @author maba, 2012-08-23
 */
public class App {

    public static void main(String[] args) throws IOException {
        ClassLoader loader = App.class.getClassLoader();
        InputStream in = loader.getResourceAsStream("app.properties");
        Properties properties = new Properties();
        properties.load(in);
        properties.list(System.out);
    }
}

System.out

-- listing properties --
resource.dir=/default/stuff/here
cfg.dir=/default/stuff/here/config
bin.dir=/default/stuff/here/bin
res.dir=/default/stuff/here

The pom.xml will have the default properties that are used by everybody.

If you want to override the values then call maven with input parameters:

mvn install -Dres.dir=/my/stuff/here -Dresource.dir="C:/${res.dir}"

System.out

-- listing properties --
resource.dir=C://my/stuff/here
cfg.dir=C://my/stuff/here/config
bin.dir=C://my/stuff/here/bin
res.dir=/my/stuff/here

By doing it this way everybody will have the same view of the properties and you can override them if you want to when running on your own machine.