使用Mule和Jersey修改JSON输出

Question

My goal is stupidly simple. I just want to wrap a json response from Jersey module in Mule in a JSON response such that:

{"status": "ok", message:<json-message>}

I tried to use a custom-transformer:

<flow name="sicsRest" doc:name="sicsRest">
    <inbound-endpoint address="http://localhost:65432/RestServices" 
        exchange-pattern="request-response" doc:name="RestEntry" />
    <jersey:resources doc:name="REST">
        <component doc:name="Java">
            <spring-object bean="serviceImpl" />
        </component>
        <custom-transformer returnClass="java.lang.String" 
            class="com.hyperborea.sicsbus.transformer.JsonTransformer" 
            doc:name="JsonTransformer" />
        <jersey:exception-mapper 
            class="com.hyperborea.sicsbus.exception.JsonRestExceptionMapper" />
    </jersey:resources>
</flow>

The transformer class:

public class JsonTransformer extends AbstractTransformer {
    @Override 
    protected Object doTransform(Object src, String enc) 
    throws TransformerException {
        return "{\"status\":\"ok\", \"message\":\"" + src + "\"}";
    }
}

Unfortunately it raises an exception during Mule startup:

org.xml.sax.SAXParseException: cvc-complex-type.2.4.a: Invalid content was found starting with element 'custom-transformer'. One of '{"http://www.mulesoft.org/schema/mule/core":abstract-component, "http://www.mulesoft.org/schema/mule/jersey":exception-mapper}' is expected.

Any suggestion?

Answer 1

What if you place your custom-transformer in a <response> ... </response> block between the inbound-endpoint and the jersey:resources ?

EDIT

New flow:

<flow name="sicsRest" doc:name="sicsRest">
    <inbound-endpoint ... />
    <response>
        <custom-transformer returnClass="java.lang.String"
            class="com.hyperborea.sicsbus.transformer.JsonTransformer"
            doc:name="JsonTransformer" />
    </response>
    <jersey:resources doc:name="REST">
        <component doc:name="Java">
            <spring-object bean="serviceImpl" />
        </component>
        <jersey:exception-mapper ... />
    </jersey:resources>
</flow>

The transformer has to be changed in an AbstractMessageTransformer in order to better handle the input (which is almost impossibile with AbstractTransformer):

public class JsonTransformer extends AbstractMessageTransformer {
    @Override 
    public Object transformMessage(MuleMessage message, String outputEncoding)
    throws TransformerException {
        try {
            return "{\"status\":\"ok\", \"message.getPayloadAsString()\":\"" 
            + src + "\"}";
        } catch (Exception e) {}
    }
}