You can download the demo from <https://github.com/mmin18/AndroidDynamicLoader/raw/master/host.apk> (35k).

In a normal Android application, we use Activity as the root UI container. But since Activity is registered in AndroidManifest.xml, and we can't modify manifest in runtime, we must find an alternative UI container - Fragment.

The Fragment itself, interduced in Android 3.0 Honeycomb, is a perfect UI container, and it has lifecycle and state management.

Once the plugin and its dependency is downloaded, an Activity (MainActivity.java) will be started, create an instance of the specific fragment, and add the fragment into the root view.

See the [HelloFragment.java](https://github.com/mmin18/AndroidDynamicLoader/blob/master/workspace/sample.helloworld/src/sample/helloworld/HelloFragment.java) sample.

Since we use Fragment as UI container, each page is implemented in Fragment instead of Activity. So how do we start a new page?

We use URL, just like a browser does. For instance, in a browser, we open `http://mydomain.com/helloworld.html`. In plugins, we open `app://helloworld`.

Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse("app://helloworld"));

startActivity(i);

Each host is mapped to a single fragment, you define the url mapping table in **project/fragment.properties**.

See the [helloworld fragment.properties](https://github.com/mmin18/AndroidDynamicLoader/blob/master/workspace/sample.helloworld/fragment.properties) sample.

`/Host` contains the host application (build as host.apk).

`/tools/update.sh` checks your environment and helps you config your plugins. You should always run it once after git clone or create a new plugin.

`/workspace/sample.helloworld` is a most simple plugin.

`/workspace/sample.helloworld/fragment.properties` defines the url mapping of your fragments.

`/site/***/site.txt` is the definition file for all the plugins files, dependency and fragments url mapping table.