Java: owner: Loading strategy MERGE

In previous post, I explained about the load startegy First, In this post, I am going to explain about load strategy Merge.

@LoadPolicy(LoadType.MERGE)

@Sources({ "file:~/.myapp.config",

         "classpath:App.properties",

    "classpath:Con.properties" })

In above snippet, owner API first tries to find tge property int the file "file:~/.myapp.config", if the property exists, then it return the value associated with this property. If the property not exist in first file, it look into the second file "classpath:App.properties", if the property exists, it return the value associated with it, else it look into the third file "classpath:Con.properties", if the property exists, then it return the value associated with it, else it return the value specified by the @DefaultValue if specified, otherwise null will be returned.

App.properties

#Project configurations
videos.directory = /Users/harikrishna_gurram/videos
maxIcons = 9

Con.properties

#Project configurations
images.directory = /Users/harikrishna_gurram/images
images.backup.directory = /Users/harikrishna_gurram/backup/images
maxIcons = 19

ProjectConfig.java

package owner_api_tutorial;

import org.aeonbits.owner.Config;
import org.aeonbits.owner.Config.Sources;
import org.aeonbits.owner.Config.LoadPolicy;
import org.aeonbits.owner.Config.LoadType;

@LoadPolicy(LoadType.MERGE)
@Sources({ "file:~/.myapp.config", 
  "classpath:App.properties", 
    "classpath:Con.properties" })
public interface ProjectConfig extends Config {

  @Key("images.directory")
  String imagesDirectory();

  @Key("images.backup.directory")
  String imagesBackupDirectory();

  @Key("videos.directory")
  String videosDirectory();

  @DefaultValue("16")
  int maxIcons();

  @DefaultValue("admin@admin.com")
  String adminMail();
}

PropertyUtil.java

package owner_api_tutorial;

import org.aeonbits.owner.ConfigFactory;

public class PropertyUtil {
  public static void main(String args[]) throws Exception {
    ProjectConfig cfg = ConfigFactory.create(ProjectConfig.class);

    System.out.println(cfg.adminMail());
    System.out.println(cfg.imagesDirectory());
    System.out.println(cfg.imagesBackupDirectory());
    System.out.println(cfg.maxIcons());
    System.out.println(cfg.videosDirectory());

  }
}

Output

admin@admin.com
/Users/harikrishna_gurram/images
/Users/harikrishna_gurram/backup/images
9
/Users/harikrishna_gurram/videos

Note

~ points to the Home directory in your machine.

$ echo ~

/Users/harikrishna_gurram

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