gwt-jackson

gwt-jackson is a JSON parser for GWT. It uses Jackson 2.x annotations to customize the serialization/deserialization process.

Most of the Jackson 2.x annotations are supported. You can find an up-to-date list here. You can also find a lot of use cases in the tests.

Jackson 1.x annotations (org.codehaus.jackson.*) are not supported.

Check the wiki for more informations.

Release process at Europace

The lib gets no updates anymore. So we update it for ourselves with new versions of Jackson locally:

1. Checkout the branch local-releases
2. Update the property jackson.version to the needed version of Jackson (also update the version of all poms accordingly)
3. Execute mvn clean install and if successful, execute mvn release:prepare
4. Push changes to Github
5. Execute mvn release:perform to deploy release to Nexus

Quick start

Add <inherits name="com.github.nmorel.gwtjackson.GwtJackson" /> to your module descriptor XML file.

Then just create an interface extending ObjectReader, ObjectWriter or ObjectMapper if you want to read JSON, write an object to JSON or both.

Here's an example without annotation :

public class TestEntryPoint implements EntryPoint {

    public static interface PersonMapper extends ObjectMapper<Person> {}

    public static class Person {

        private String firstName;
        private String lastName;

        public String getFirstName() {
            return firstName;
        }

        public void setFirstName(String firstName) {
            this.firstName = firstName;
        }

        public String getLastName() {
            return lastName;
        }

        public void setLastName(String lastName) {
            this.lastName = lastName;
        }
    }

    @Override
    public void onModuleLoad() {
        PersonMapper mapper = GWT.create( PersonMapper.class );

        String json = mapper.write( new Person( "John", "Doe" ) );
        GWT.log( json ); // > {"firstName":"John","lastName":"Doe"}

        Person person = mapper.read( json );
        GWT.log( person.getFirstName() + " " + person.getLastName() ); // > John Doe
    }
}

And if you want to make your class immutable for example, you can add some Jackson annotations :

public class TestEntryPoint implements EntryPoint {

    public static interface PersonMapper extends ObjectMapper<Person> {}

    public static class Person {

        private final String firstName;
        private final String lastName;

        @JsonCreator
        public Person( @JsonProperty( "firstName" ) String firstName,
                       @JsonProperty( "lastName" ) String lastName ) {
            this.firstName = firstName;
            this.lastName = lastName;
        }

        public String getFirstName() {
            return firstName;
        }

        public String getLastName() {
            return lastName;
        }
    }

    @Override
    public void onModuleLoad() {
        PersonMapper mapper = GWT.create( PersonMapper.class );

        String json = mapper.write( new Person( "John", "Doe" ) );
        GWT.log( json ); // > {"firstName":"John","lastName":"Doe"}

        Person person = mapper.read( json );
        GWT.log( person.getFirstName() + " " + person.getLastName() ); // > John Doe
    }
}

With Maven

<dependency>
  <groupId>com.github.nmorel.gwtjackson</groupId>
  <artifactId>gwt-jackson</artifactId>
  <version>0.15.4</version>
  <scope>provided</scope>
</dependency>

You can also get maven snapshots using the following repository :

<repository>
  <id>oss-sonatype-snapshots</id>
  <url>https://oss.sonatype.org/content/repositories/snapshots</url>
  <snapshots>
    <enabled>true</enabled>
  </snapshots>
</repository>

Without Maven

In addition of gwt-jackson jar you can find here, you also need

• jackson-annotations-2.7.2.jar
• jackson-annotations-2.7.2-sources.jar for the GWT compilation only
• javapoet-1.0.0.jar for the GWT compilation only

Server communication

If you need to communicate with your server using REST/Json payload, you can check these framework which integrates gwt-jackson :

• GWTP Rest Dispatch. Check the example.
• RestyGWT. Check the example.
• Requestor. Check the example.
• gwt-jackson-rest. Check the example.
• GWT RequestBuilder. Check the example.

Copyright and license

Copyright 2014 Nicolas Morel under the Apache 2.0 license.