Do you want to get java file from war file ? or
Do you want to convert war file into java file?
If you want to extract java file in the war file then do the following steps
1)locate the war file using windows explorer.
2)Change the extension of the file from .war to .zip
3) Extract that zip file in suitable location and locate your java file. If you have not included java files during build then locate desired class file
4) decomplie that class file into desired java file using 'jad' utility or 'DJ Java Decompiler' easily available on internet