"Go". apk files and Dex files in Android system

1. *.apk file

APK is the abbreviation for Android package, which is the Android installer. Install the APK file by uploading it directly to the Android emulator or Android phone.

Use the Android Packaging tool (AAPT) to combine Dex files, resource files, and Androidmanifest.xml files into an application package (APK). Dex is the full name of the Dalvik VM executes, the Android Dalvik execution program.

• meta-inf\ jar File
• Res\ Storing resource files
• Androidmanifest.xml applying a global configuration file
• *.dex Dalvik Virtual Machine byte code (application)
• RESOURCES.ARSC compiled binary resource file

Android will first need to unzip the APK file when running the program, then obtain the configuration information in the compiled Androidmanifest.xml file and execute the DEX program.

2..dex file

Dex is the full name of the Dalvik VM executes, the Android Dalvik execution program, which is typically optimized for execution. The optimized file size will increase. There are two times when optimization occurs: For a preset application, you can generate an optimization file after the system compiles to odex the end. This way, there is a corresponding Android Dex file in addition to the APK file (without Dex) at the time of release, and for non-provisioned apps, the Dex file contained in the APK file is optimized at run time and the optimized file is saved in the cache.

Zygote is a virtual machine process and an incubator of virtual machine instances, and whenever a system requires an Android application to execute, Zygote will fork out a subprocess to execute the application. The benefits of this are obvious: the zygote process is generated when the system starts, it completes the initialization of the virtual machine, the loading of the library, the loading and initialization of the pre-set class library, and so on, while the system needs a new instance of the virtual machine.

Zygote provides the fastest system by replicating itself. In addition, for some read-only system libraries, all virtual machine instances share a chunk of memory with zygote, saving significant memory overhead.

From:http://blog.chinaunix.net/uid-24439730-id-355883.html

"Go". apk files and Dex files in Android system