Gson

Gson, Google’s JSON library, is known for its simplicity and zero-dependency design. It handles most serialization needs out of the box without requiring extensive configuration. JobRunr supports Gson through the GsonJsonMapper implementation.

Gson is in maintenance mode, meaning that it may not see any new features.

Installation

Add Gson to your project dependencies. Configuration for other build tools can be found on Maven Central: https://central.sonatype.com/artifact/com.google.code.gson/gson.

Maven

<dependency>
  <groupId>com.google.code.gson</groupId>
  <artifactId>gson</artifactId>
  <version><!-- latest version --></version>
</dependency>

Gradle

implementation 'com.google.code.gson:gson' // version omitted, use latest

Usage

JobRunr automatically detects Gson on your classpath and uses it for serialization. When multiple JSON libraries are available, Gson has the fourth-highest priority in the detection hierarchy.

If auto-detection doesn’t work, you can manually configure it:

JobRunr.configure()
  .useJsonMapper(new GsonJsonMapper())
  //...
  .initialize();

Or when using a supported framework, define a JsonMapper bean. Example for Spring (can easily be adapted for other frameworks):

import org.jobrunr.utils.mapper.JsonMapper;

@Bean
public JsonMapper jsonMapper() {
    return new GsonJsonMapper();
}

Custom Gson configuration

Customize Gson by creating your own GsonJsonMapper instance. The class offers three constructors depending on your needs.

Before proceeding, note that JobRunr may overwrite your custom configuration. Verify through testing that everything behaves as expected.

Using GsonBuilder

Pass a configured GsonBuilder to customize serialization behavior:

var gsonBuilder = new GsonBuilder()
  .registerTypeAdapter(MyCustomType.class, new MyCustomTypeAdapter());

var jsonMapper = new GsonJsonMapper(gsonBuilder);

Using a pre-configured Gson instance

If you already have a Gson instance configured elsewhere in your application, you can reuse it:

Gson gson = // ... your existing Gson instance
var jsonMapper = new GsonJsonMapper(gson);

Using this may prevent JobRunr from functioning properly. Prefer the builder or option or make sure that your Gson instance has all the configuration required by JobRunr.