Comparing JSON libraries

Sean SullivanPortland Java User Group

July 19, 2011

JavaScript Object Notation

pentagon hexagon json

{ “hello” : “world”, “count” : 1 }

JSON is a data interchange format

{

“name” : “Mock Crest Tavern”,

“tags” : [ “music”, “beer”, “tots” ],

“location” :

{

“city” : “Portland”,

“state” : “Oregon”

}

}

• based on a subset of the JavaScript programming language

• text format

• language independent

JSON

RFC 4627

How is JSON useful to Java developers?

Web Services

“In the first version of our API, data was available in XML, with JSON support added largely as an afterthought. XML as a means for delivering developer-friendly data hasn’t aged well. Seeing the growing inclination of developers and API makers alike towards JSON, we’ve decided to eliminate XML support and put the energy spent there into getting our JSON implementation just right.”

July 2011

http://engineering.tumblr.com/post/7541361718/introducing-tumblrs-new-api

JSON libraries

• json.org library

• Google GSON

• Jackson

• lift-json

http://json.org/javadoc

import org.json.*;

JSONObject obj = new JSONObject();

obj.put(“Hello”, “World”);

obj.put(“count”, 1);

String json = obj.toString();

http://jackson.codehaus.org/

import org.codehaus.jackson.*;

import org.codehaus.jackson.map.*;

ObjectMapper mapper = new ObjectMapper();

String json = mapper.writeValueAsString(foo);

Foo foo2 = mapper.readValue(json, Foo.class);

http://code.google.com/p/google-gson/

import com.google.gson.*;

GsonBuilder builder = new GsonBuilder();

Gson gson = builder.create();

String json = gson.toJson(foo);

Foo foo2 = gson.fromJson(json, Foo.class);

Jackson vs GSON

• GSON serializes all non-transient non-static fields. GSON accesses fields directly with Java’s Reflection API

• Jackson uses JavaBean methods (setter methods / getter methods)

JSON and Scala

lift-json

JSON and Android

json.org JsonReader, JsonWriter

Android 1.x Y N

Android 2.x Y N

Android 3.x Y Y

Benchmarks

Related topics

Native JSON

http://blog.mozilla.com/webdev/2009/02/12/native-json-in-firefox-31/

http://blogs.msdn.com/ie/archive/2008/09/10/native-json-in-ie8.aspx

For more information

• http://www.json.org

• http://en.wikipedia.org/wiki/JSON

Thank you