json java libraries benchmark - jsonlib, jackson, gson

Because I don't parse huge json string so I only test object binding which is much more convenient. For the same reason, I did not have jettison or gson-streaming in this test because they are much faster with the trade-off of lower level of encapsulation and OOP.

For gson and jackson, the instance of Gson and ObjectMapper can be reused. Jackson performs very good because its ObjectMapper caches class mapping meta data. Jackson will be slow if you don't reuse ObjectMapper, it's designed for reuse.

The scala built-in parser is extremely slow (100 X slower!) and lift-json is the defacto lib for scala, which is about 15% slower than jackson.

-	Bean to JSON	JSON to Bean
Jsonlib 2.4	2058	3055
Gson 1.7	1481	1472
Jackson 1.7.6	694	667

Test env: jdk6 on Mac OS X 10.6.7
unit: millseconds

Conclusion: Jackson is the best solution for server side because of its cache. Another win of jackson is that it has zero dependency, jsonlib sucks a lot in both performance and dependency. Gson is also very fast with zero dependency, without cache, it's ad-hoc usage is the best, it's best for less heavy use of json, like android device or web start applet (170K only).