Installing the anti-compile plugin under eclipse allows you to view the appropriate Java source code for the. class file directly.
The anti-compile plugin has jdeclipse and jadeclipse.
(1) jdeclipse
http://www.djjavadecompiler.com/
(2) Jad + jadeclipse
Download Jadeclipse:http://sourceforge.net/projects/jadclipse/files/
Or see my note-taking address:
http://note.youdao.com/yws/public/resource/bd5eb7f827b10534088c7c5085208bbe/355468C26CA948358BF4458CA68A6828
After downloading Net.sf.jadclipse_3.3.0.jar, copy to the plugin folder under the Eclipse home folder. Then restart Eclipse.
Download Jad.exe:http://www.varaneckas.com/jad/(address found on wiki)
Or see my note-taking address:
http://note.youdao.com/yws/public/resource/bd5eb7f827b10534088c7c5085208bbe/B06333506D5E428787F0FF14B55F5090
after downloading, copy to random path, such as I copy to%java_home%\bin, namely: D:\Program Files\java\jdk1.6.0_33\bin\jad.exe
And then:
Window->preferences->java->jadclipse. Fill in path to decompiler with the full pathname of the Anti-compilation tool Jad, which is:D:\Program Files\java\jdk1.6.0_33\bin\jad.exe.
And then:
File associations, Editors, Perference, Windows,
Under File Type, select *.class. Then select the Jadclipse Class File Viewer under associated editors. and click on the default button on the right side to set it as the Defaults editor.
  Note, After you set this up, you can still double-click some. class files that cannot be deserialized because these class files do not have additional source code. To resolve all class files, you need to do the following:
Under File type, select *.class without source, (if there is no option, you can try clicking on the right side AddButton yourself to join the *.class without source type), and then Associated editors Click on the right side add, add the Jadclipse class file Viewer, then select the Jadclipse class file viewer and click DefaultButton on the right. Set the Jadclipse Class File Viewer to the default editor for *.class without source .
Eclipse 4.2 Installing the Java Anti-compilation plugin