View Source Code of JAR File

In Eclipse

1. Attach Source Code

get a JAR file containing source code.

If double-click Class file, one can see a button of attach source.

or If right-click JAR file, Properties > Java Source Attachment > select Source JAR file.

2. Use JAD Decompiler

http://jadclipse.sourceforge.net/wiki/index.php/Main_Page

3. Use Maven when a project is using Maven and m2eclipse

Right-click a JAR file, Maven > Download Sources

Reference

http://blog.nya.pe.kr/45