How i can view the contents of Jar files and enter to it like Zip files on windows 7 , so windows explorer can view these files ?
Try this registry script:
Windows Registry Editor Version 5.00 [HKEY_CURRENT_USER\SOFTWARE\Classes\.jar] @="CompressedFolder"
Jar (=Java Archive) are just zipped Java class files, so you can use any Zip-Archiver tool to unzip it, for example 7-zip.
It won't bring you much, however, because class files are the files compiled into bytecode, so this is a binary format you cannot easily look in. You can decompile these files using some of existing Java decompilers, for example this one.
Open them with 7-zip. If you really want to double click, set it as default program for