zipalign is an archive alignment tool that provides important optimization to Android application (.apk) files. The purpose is to ensure that all uncompressed data starts with a particular alignment relative to the start of the file. Specifically, it causes all uncompressed data within the .apk, such as images or raw files, to be aligned on 4-byte boundaries. This allows all portions to be accessed directly with  even if they contain binary data with alignment restrictions. The benefit is a reduction in the amount of RAM consumed when running the application.

This tool should always be used to align your .apk file before distributing it to end-users. The Android build tools can handle this for you. When using Eclipse with the ADT plugin, the Export Wizard will automatically zipalign your .apk after it signs it with your private key. The build scripts used when compiling your application with Ant will also zipalign your .apk, as long as you have provided the path to your keystore and the key alias in your project  file, so that the build tools can sign the package first.

The adjustment is made by altering the size of the "extra" field in the zip Local File Header sections. Existing data in the "extra" fields may be altered by this process.

For more information about how to use zipalign when building your application, please read Signing Your Application.

Usage

To align  and save it as :

To confirm the alignment of :

The  is an integer that defines the byte-alignment boundaries. This must always be 4 (which provides 32-bit alignment) or else it effectively does nothing.

Flags:

•  : overwrite existing outfile.zip
•  : verbose output
•  : confirm the alignment of the given file

刚认真研究发现一点：

When using Eclipse with the ADT plugin, the Export Wizard will automatically zipalign your .apk after it signs it with your private key.

也就是说用eclipse export打包的apk是已经zipalign过的了