You can use microsoft's EWS api which is open source for android by doing the following steps,
Download the source code available in the URL,
http://archive.msdn.microsoft.com/ewsjavaapi
EWSJavaAPI_1.1.5.zip
Make the changes to above api to work for JDK 1.4 in eclipse like remove override annotations etc
Download source code of javax.*
package available in below URL,
http://www.java2s.com/Code/Jar/j/Downloadjsr17310srcjar.htm
jsr173_1.0_src.jar.zip
Download source code of stax api available in below URL,
http://dist.codehaus.org/stax/distributions
stax-src-1.2.0.zip
Keep all the sources under the single java project in eclipse
Open the project explorer and select the package which are starts with "javax" and rename to your company name eg: com. Note: Eclipse will ask for all the naming contexts will change then click OK.
Export all the java sources to one single jar file.
You are good now to go to use the jar in Android application with out any problems.
I used the same way explained above and it worked in android application 100% perfectly.