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javajaxbjax-wsjerseyjackson

jackson with jaxb

when using Jackson JSON processor in Jersey, when and why would I need to use JAXB annotations in between? Object->JAXB->JSON

Jackson also provides it's own JAX-RS provider to go direct Object->JSON. what is missing in this approach? or why would I prefer on over another

ps: I use also spring

Solution

  • For generating JSON you generally just have to specifiy @Produces(MediaType.APPLICATION_JSON). This will however take the JAXB route by default.

    With Object -> JAXB -> JSON you will have to annotate the classes you want to map with @XmlRootElement. This will work fine, but once you get to serializing a HashMap you will not end up with an obvious {keyOne:"one",keyTwo:"two"} but rather something strange like {entry:[{key:"keyOne",value:"one"},{key:"keyTwo",value:"two"}]}.

    So to take the direct Object -> JSON way, just specify the following in your web.xml:

        <init-param>
        <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
        <param-value>true</param-value>
    </init-param>

    With this JSON mapping will work just the way you would expect it to work. Just don't forget to remove the @XmlRootElement annotations, they force XML generation when POJO mapping is turned on.

    Also have a look at my question regarding this: Java.util.Map to JSON Object with Jersey / JAXB / Jackson

    Reference: http://jersey.java.net/nonav/documentation/latest/json.html#d4e894