Reading properties files made easy using OWNER library. No more boilerplate code

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No more boilerplate code for properties files

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We use properties files all over for our development to store configurable data of our applications and the same is true when it comes to test automation. We store config params in properties files.

Properties files store data as key-value pairs similar to a Java map data structure. Below is an example of a properties file.

server.host.name=testing.com
parallel=true
maxThreads=100

We can use java boilerplate code to read properties files and use them during the program execution. There are disadvantages of this approach like,

·        Need to maintain a separate code to read/write values to properties file

·        Keys can get duplicated and hence values may differ

·        Type conversion has to be managed

Good news!

What do you think if someone else takes care of all the above hassle for you and you just need to create properties file, add values and then introduce an interface to load all the data.

The owners library takes care of all these things for you. Here is the official website of owners library.

OWNER

No more code to load, convert and manage properties files, just use your properties in the simplest possible way. See…

owner.aeonbits.org

 

Let’s look at the usage of the owners library to read properties files in our application. It comes as a Jar library and as well as a maven dependency. If you are using maven, you can import the below dependency and start using the greatest features of owners library.

<dependency>
        <groupId>org.aeonbits.owner</groupId>
        <artifactId>owner</artifactId>
        <version>1.0.8</version>
    </dependency>

In this article, let’s use the above example and develop our code leveraging owners library.

Next is to generate the interface to load the properties in the file.

import org.aeonbits.owner.Config;public interface ServerConfig extends Config {
    boolean parallel();    @Key("server.host.name")
    String hostname();    @DefaultValue("5")
    int maxThreads();
}

The condition is the variable name should be the same as the property name specified in the properties file. If it is different, as in hostname, you can specify the name using the @Key annotation.

Moreover, if you look closely at the maxThreads, you can specify the default value as a safety net.

Now the question is how do you map the two files, the properties file, and the java interface.

Rule 1
If both the files are in the same package, with the same name, then the owners will find and read the value of the properties file.

Rule 2

In most cases, we want to store the properties file in a separate directory and hence you need to specify the file path using @sources annotation as below.

My file is residing inside the resources folder under the test package.

@org.aeonbits.owner.Config.Sources({
        "file:./src/test/resources/config.properties"})
public interface ServerConfig extends Config {
    boolean parallel();    @Key("server.host.name")
    String hostname();    @DefaultValue("5")
    int maxThreads();
}

With all these, next is to use the values from the properties files inside our application.

We are initiating the ServerConfig via the ConfigFactory provided by the owners.

ServerConfig cfg = ConfigFactory.create(ServerConfig .class);
cfg.hostname;
cfg.maxThreads;

Final Thoughts

· The owners library helps to remove the boilerplate code used for reading properties files.

· Owners takes care of type conversion and load strategies

· Owners library is an annotation-based library easy to maintain.