REST Web服务未返回JSON数组

Question

In the web service call, if the response is a list containing a single element, the REST web service returns a JSON object instead of a JSON array. How can I always return an array?

@GET
@Produces("application/json")
@Path("/chekinList")
public List<LocationReguest> getChekinList(@FormParam("childID") String userName,@FormParam("appkey") String appkey,@FormParam("appPassword") String appPassword) // Getting the list of check in list
{

    LocationController locationController = new LocationController(); //Controller object
    List<LocationReguest> locreqlist = locationController.getChekinList(userName);   //Calling controller function
    return locreqlist;   //return proper representation object
}

Example :

JSON Object output when having one object

{"childRequest":{"childName":"test123Child","childUserName":"add"}}

JSON Object array output when having more objects:

{"childRequest":[{"childName":"Child ONE","childUserName":"chlid1"},{"childName":"abayakoon","childUserName":"abey"}]}

Answer 1

You need to write a custom implementation of MessageBodyWriter, but instead of reinventing the wheel perhaps it's easier to just use a dependency containing it:

<dependency>
  <groupId>com.fasterxml.jackson.jaxrs</groupId>
  <artifactId>jackson-jaxrs-json-provider</artifactId>
  <version>2.4.2</version>
</dependency>

It adds a provider to the classpath used by JAX-RS to serialize the return value of a REST call to JSON, in your case List<LocationReguest> . The way this implementation serializes lists is to always return a JSON array, even for the single argument list. Just how you want it.

At the moment it's likely that your app already has a provider that knows how to serialize lists, so what dependencies are you currently using?