how to open an .apk file

hi i am a new developer, i created开发者_运维问答 an app of my own. I created the .apk file and get it signed and aligned it. When i was running it on my device i thought of doing some changes in it, but i missed the original source code. Can i get back my source code using the aligned.apk file... I am using eclipse

The apk is just a zip file so you can unzip it. Your code will be in a classes.dex file in the dalvik format. There are some tools you can use to convert it back from dex2jar, and then decompile the class files using jad but your source code will most likely be imcomplete.