so the questions as in the title, I need to run my server application in Tomcat on a System which is 32 bit Windows XP, I am working and compiling on my 64 bit Windows 7 in Eclipse. How do I compile it to 32 bit, what do I need to do? I assume it won't work on the 32 bit Windows when I'm compiling it on a 64 bit machine?
Java doesn't build 32-bit or 64-bit applications - bytecode is portable across different bit architectures.
The only exception is native libraries that you might be using in your code. If there are any then you will have to manually compile those for the respective platform. Otherwise the java code is totally portable across 32-bit and 64-bit platforms.
The problem is your JNI DLL, which needs to be compiled for 32-bit to match the 32-bit JRE.
Java is independent of the OS.
You can compile with your 64bit machine and run this on a 32bit computer as long as this computer has a 32bit VM.
If you're still searching for some "simple" solution, one would be to install a 32 bit os in a virtual machine and run eclipse from there.. Very ugly I know, but it works.
Another approach is mentioned here. How to launch java swing app which used precompled DLL from cmd?
You could install a 32bits jdk on a 64bits machine. point the JAVA_HOME to this jdk and use it. It
来源：https://stackoverflow.com/questions/17145781/compile-32-bit-java-builds-on-64-bit-machine-with-eclipse