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
mmap() 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. Android Studio automatically aligns your APK.
Caution: You must use zipalign at one of two specific points in the app-building process, depending on which app-signing tool you use:
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.
infile.apk and save it as
zipalign [-f] [-v] <alignment> infile.apk outfile.apk
To confirm the alignment of
zipalign -c -v <alignment> existing.apk
<alignment> is an integer that defines the byte-alignment boundaries.
This must always be 4 (which provides 32-bit alignment) or else it effectively
-f: overwrite existing outfile.zip
-v: verbose output
-p: outfile.zip should use the same page alignment for all shared object files within infile.zip
-c: confirm the alignment of the given file