APK Shrinking Practices for JD Finance Android App

Background – The JD Finance Android app grew rapidly, exceeding 117 MB from 2019‑2022, which negatively impacted download conversion, installation time, and device storage. A dedicated slimming campaign started in September 2022 and reduced the package to 74 MB without removing business code.

APK Content Analysis – The APK is a ZIP archive containing classes.dex , resources.arsc , res/ , lib/ , assets/ , META-INF/ , and AndroidManifest.xml . Understanding each component’s size is essential for targeted reduction.

SDK Size Analysis – Using the internal Pandora tool, the sizes of third‑party SDKs were visualized, revealing that many SDKs (especially those with multiple native .so libraries) contributed heavily to the overall size.

ZIP Structure Analysis – The zipinfo -l --t --h test.apk > test.txt command lists each file’s original and compressed sizes, enabling per‑file size indexing and identification of compression opportunities.

Shrinking Practices

Image Optimization – Convert all images to WebP, apply multi‑DPI merging, and run Pngquant for lossy compression.

R‑file Inlining – Replace R.layout.xxx references with raw integer IDs (e.g., setContentView(2131427356); ) and then delete the generated R classes.

AndResGuard – Shorten resource names in resources.arsc to reduce the resource table size.

7‑zip Compression – Re‑package the unsigned APK with 7za a -tzip -mx9 target.zip extracted_dir , then store uncompressed files (e.g., native libraries) with -mx0 to avoid runtime decompression overhead.

CPU Architecture Configuration – Build only arm64‑v8a binaries via ndk { abiFilters "arm64-v8a" } .

resources.arsc Compression – Although compressing resources.arsc saves space, it can increase memory usage and start‑up time; therefore it is disabled for targetSdkVersion ≥ 30.

Internationalization – Remove unused language resources with defaultConfig { resConfigs "zh", "en" } .

shrinkResources & minifyEnabled – Enable both flags in build.gradle to delete unused resources and code.

Advanced Technical Solutions

Dynamic SO Loading – Download required .so libraries at runtime and inject them into the class loader using reflection (see code snippet below).

Pluginization – Split the monolithic APK into independent plugin modules that can be loaded on demand, allowing hot‑fixes and reducing the base package size.

System.load("{secure_path}/libxxx.so")
// Reflective injection of new native library paths
final Field pathListField = ShareReflectUtil.findField(classLoader, "pathList");
final Object dexPathList = pathListField.get(classLoader);
final Field nativeLibraryDirectories = ShareReflectUtil.findField(dexPathList, "nativeLibraryDirectories");
List
origLibDirs = (List
) nativeLibraryDirectories.get(dexPathList);
origLibDirs.add(0, new File(folder));
final Method makeElements = ShareReflectUtil.findMethod(dexPathList, "makePathElements", List.class);
Object[] elements = (Object[]) makeElements.invoke(dexPathList, origLibDirs);
final Field nativeLibraryPathElements = ShareReflectUtil.findField(dexPathList, "nativeLibraryPathElements");
nativeLibraryPathElements.set(dexPathList, elements);

Business Optimization & Governance – Low‑UV business modules are evaluated for removal or pluginization. A control platform monitors package changes across builds, flags regressions, and enforces SDK size limits.

Results & Future Plans – After two quarters and five releases, the APK size stabilized at ~74 MB. Ongoing plans include automating the slimming pipeline, integrating the control platform with CI/CD, and periodic audits to prevent size regression.

References

Google Play: Shrinking APKs – link

ProGuard – link

R8 – link

AndResGuard – link