Java JSON library for generics

Question

Is there a JSON library for Java that can handle something like the following scenario:

public class BaseShapeSender<T extends Shape> {
{
  Collection<T> shapes;

  public void send
  {
    // Sending the shapes collection with JSON
  }
}

public class CircleSender extends BaseShapeSender<Circle>
{

}

Currently I'm using Jersey, but calling circleSender.send() with the above above scenario gives an exception

A message body writer for Java type, class java.util.ArrayList, and MIME media type, application/json, was not found

even when using GenericEntity to send the collection (apparently Jersey can handle Collection<Circle> but the second level of generics is too much). So, I found myself duplicating the sending code in every subclass:

public class CircleSender extends BaseShapeSender<Circle>
{
  Collection<Circle> circles;

  public void send
  {
    // Sending the circles collection with JSON
  }
}

I would love to avoid that if possible since the sending logic is basically the same in all subclasses.

look at Google's GSon library – Umesh Awasthi Feb 03 '12 at 08:00 — Umesh Awasthi, Feb 03 '12 at 08:00

score 2 · Answer 1 · answered Feb 03 '12 at 08:13

2

One of the best JSON library for Java is Jackson (http://jackson.codehaus.org).

We use it with Jersey and Resteasy and it's very good. You may automate object transformation without writing any factory or extra code. It's just automatic. There are a lot of advanced features and it is proven. I believe it is the standard for Java.

It also supports templating. Here is an example:

List<User> list = getUserService().getAllUsers();
Writer writer = new StringWriter();
getObjectMapper().writeValue(writer, list);

answered Feb 03 '12 at 08:13

unludo

4,912
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How does it integrate with Jersey? Don't they perform the same job (serializing Java objects to JSON strings and vice versa)? – Alex Feb 03 '12 at 08:19
No in fact Jersey manages the REST part. You need to convert the argurments (both input and output if you want to convert from/to JSON). When you convert the output to a string with Jackson, return it in the REST controller and is is sent in response. I found an example here http://www.mkyong.com/webservices/jax-rs/json-example-with-jersey-jackson/. I mainly use Resteasy which is a bit different. – unludo Feb 03 '12 at 08:32

score 1 · Accepted Answer · edited May 23 '17 at 12:13

1

According to this answer Jackson supports both generics as well as polymorphism. GSON (which I've stuck with so far) does not until issue 231 is resolved.

edited May 23 '17 at 12:13

Community

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answered Feb 03 '12 at 08:11

Ben Schulz

6,101
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Java JSON library for generics

2 Answers2