toughie88 / Android-Hotpatch

Update an android app on the fly

Android-Hotpatch

Update or fix an android app on the fly, without having to publish a new APK.

Usage:

1. Make a .jar library with your app's classes and methods that you want to be updatable (see compiling your application as a library)
2. Grab Hotpatch.java and add it to your project
3. Load the .jar library you built earlier

You might need to do a small refactor of your app's code, but the advantages are many:

• Quickly fix & deploy a patch for a method
• Add methods to classes
• Hotpatch does not need the app to restart
• Updating an app using Hotpatch does not require root!

Quick usage demo:

Let's say we have a class that we want to use in our Android app, defined this way:

package com.chars.testlib.TestLib;

public class TestLib {
     public String getVersionString() {
        return "libversion 1.0";
     }
}

After making a .jar library of that class, deploy it to you device i.e in /sdcard/TestLib.jar

In order to use it in your Android app, you must load it with Hotpatch

final String className = "com.chars.testlib.TestLib";
final String methods[] = {"getVersionString"};

final Hotpatch hotpatch = new Hotpatch();

try {
    hotpatch.loadLibrary("/sdcard/TestLib.jar", getApplicationContext());
    hotpatch.loadClass(className);
    hotpatch.loadMethods(className, methods);

    String result = (String)hotpatch.call(className, methods[0]);
    Log.d("AndroidHotpatch", result);

} catch (Exception e) {
    Log.e("AndroidHotpatch", Log.getStackTraceString(e));
}

The line

    String result = (String)hotpatch.call(className, methods[0]);

will execute the getVersionString() method, defined in class TestLib.

To update the library, just make a new .jar from an updated version of the class. For example:

package com.chars.testlib.TestLib;

public class TestLib {
     public String getVersionString() {
        return "libversion 2.0";
     }
}

Push the updated .jar to the same path as the previous. In your Android app, you can just call

    hotpatch.reload();

and you'll have your updated library loaded into the app. Now, whenever you execute getVersionString() you will get "libversion 2.0"

Compiling an application as a library (Android Studio / Eclipse):

1. Start a new android project
2. Add the classes that you want to be updatable
3. Build an APK
4. Rename the .apk file to .jar

Changelog

• v0.1 Alpha:
  • Support for methods
  • Implemented Hotpatch.loadLibrary()
  • Implemented Hotpatch.loadClass()
  • Implemented Hotpatch.loadMethods()
  • Implemented Hotpatch.reload()
  • Implemented Hotpatch.call()