For JSON to object marshalling, Camel provides integration with three popular JSON libraries:
By default Camel uses the XStream library.
Using JSON data format with the Jackson library
from("activemq:My.Queue").
marshal().json(JsonLibrary.Jackson).
to("mqseries:Another.Queue");
Using JSON data format with the GSON library
from("activemq:My.Queue").
marshal().json(JsonLibrary.Gson).
to("mqseries:Another.Queue");
Using JSON in Spring DSL
When using Data Format in Spring DSL you need to declare the data formats first. This is done in the DataFormats XML tag.
<dataFormats>
<!-- here we define a Json data format with the id jack and that it should use the TestPojo as the class type when
doing unmarshal. The unmarshalTypeName is optional, if not provided Camel will use a Map as the type -->
<json id="jack" library="Jackson" unmarshalTypeName="org.apache.camel.component.jackson.TestPojo"/>
</dataFormats>
And then you can refer to this id in the route:
<route>
<from uri="direct:back"/>
<unmarshal ref="jack"/>
<to uri="mock:reverse"/>
</route>
Excluding POJO fields from marshalling
As of Camel 2.10
When marshalling a POJO to JSON you might want to exclude certain fields from the JSON output. With Jackson you can use JSON views to accomplish this. First create one or more marker classes.
public class Views {
static class Weight { }
static class Age { }
}
Use the marker classes with the @JsonView annotation to include/exclude certain fields. The annotation also works on getters.
@JsonView(Views.Age.class)
private int age = 30;
private int height = 190;
@JsonView(Views.Weight.class)
private int weight = 70;
Finally use the Camel JacksonDataFormat to marshall the above POJO to JSON.
JacksonDataFormat ageViewFormat = new JacksonDataFormat(TestPojoView.class, Views.Age.class);
from("direct:inPojoAgeView").marshal(ageViewFormat);
Note that the weight field is missing in the resulting JSON:
The GSON library supports a similar feature through the notion of ExclusionStrategies:
/**
* Strategy to exclude {@link ExcludeAge} annotated fields
*/
protected static class AgeExclusionStrategy implements ExclusionStrategy {
@Override
public boolean shouldSkipField(FieldAttributes f) {
return f.getAnnotation(ExcludeAge.class) != null;
}
@Override
public boolean shouldSkipClass(Class<?> clazz) {
return false;
}
}
The GsonDataFormat accepts an ExclusionStrategy in its constructor:
GsonDataFormat ageExclusionFormat = new GsonDataFormat(TestPojoExclusion.class, new AgeExclusionStrategy());
from("direct:inPojoExcludeAge").marshal(ageExclusionFormat);
The line above will exclude fields annotated with @ExcludeAge when marshalling to JSON.
Dependencies for XStream
To use JSON in your camel routes you need to add the a dependency on camel-xstream which implements this data format.
If you use maven you could just add the following to your pom.xml, substituting the version number for the latest & greatest release (see the download page for the latest versions).
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-xstream</artifactId>
<version>2.9.2</version>
</dependency>
Dependencies for Jackson
To use JSON in your camel routes you need to add the a dependency on camel-jackson which implements this data format.
If you use maven you could just add the following to your pom.xml, substituting the version number for the latest & greatest release (see the download page for the latest versions).
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-jackson</artifactId>
<version>2.9.2</version>
</dependency>
Dependencies for GSON
To use JSON in your camel routes you need to add the a dependency on camel-gson which implements this data format.
If you use maven you could just add the following to your pom.xml, substituting the version number for the latest & greatest release (see the download page for the latest versions).
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-gson</artifactId>
<version>2.10.0</version>
</dependency>
