How to do XML <-> JSON?

One option found:
http://beckchr.github.com/staxon/

What are the JSON Library Which Can Be Use in JDK 1.4?

I have found these links:

http://stringtree.org/stringtree-json.html

https://github.com/douglascrockford/JSON-java

http://www.rojotek.com/blog/2009/05/07/a-review-of-5-java-json-libraries/

How to Convert Excel Data to JSON?

We came across this useful site:
http://shancarter.com/data_converter/

How to perform Struts Validation (JSON Based)?

Good example in http://code.google.com/p/struts2-jquery/wiki/Validation

Custom Jackson's ObjectMapper in Spring Framework

Method No 1: Prevent cross-site scripting when using JSON objects using ESAPI and Jackson framework 1.7.x

 Another link showing JaxbJacksonObjectMapper.

 Another link showing option 3: How to customise the Jackson JSON mapper in Spring Web MVC? Method as described in jackson-module-hibernate

One example of how to write the JSONResult

Example 2: Creating a Login Interceptor in Struts 2 - Same concept can be use to write the JSONResult and configure in Spring

How to Mybatis <-> Json?

This Chinese article gives an example: http://www.iteye.com/topic/974139

How to JSON <-> XML?

Possible Paser Choice: Jackson : http://jackson.codehaus.org/ plus a plugin will do the trick - Plugin for the Jackson Parser: https://github.com/lukas-krecan/json2xml