Dynamic fragment loading

Activities.java

package pl.selvin.fragmentloader;

import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ProgressBar;

import com.squareup.okhttp.OkHttpClient;
import com.squareup.okhttp.Request;
import com.squareup.okhttp.Response;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;

import dalvik.system.DexClassLoader;
import okio.BufferedSink;
import okio.Okio;


public class Activities {

    public static class MainActivity extends AppCompatActivity {

        private final static String[][] setupData = new String[][]{
                new String[]{"http://selvin.pl/dynamicfragment.jar", "pl.selvin.dynamicfragment.Fragment1"},
                new String[]{"http://selvin.pl/dynamicfragment.jar", "pl.selvin.dynamicfragment.Fragment2"},
                new String[]{"http://selvin.pl/dynamicfragments2.jar", "pl.selvin.dynamicfragments2.Fragment1"}
        };

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            final LinearLayout layout = new LinearLayout(this);
            layout.setOrientation(LinearLayout.VERTICAL);
            final View.OnClickListener buttonClick = (new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    final String[] rowData = (String[]) v.getTag();
                    final Intent intent = new Intent(MainActivity.this, GenericActivity.class);
                    intent.putExtra(GenericActivity.JAR_URL, rowData[0]);
                    intent.putExtra(GenericActivity.FRAGMENT_CLASS_NAME, rowData[1]);
                    startActivity(intent);
                }
            });
            for (int r = 0; r < setupData.length; r++) {
                final Button button = new Button(this);
                layout.addView(button);
                final String[] rowData = setupData[r];
                button.setText(rowData[0] + "\n" + rowData[1]);
                button.setTag(rowData);
                button.setOnClickListener(buttonClick);
            }

            setContentView(layout);
        }
    }


    public static class GenericActivity extends AppCompatActivity {
        public static String JAR_URL = "JAR_URL";
        public static String FRAGMENT_CLASS_NAME = "FRAGMENT_CLASS_NAME";

        //there should be better way - do not use it in production
        private static DexClassLoader loader;
        //url that we already loaded
        private static ArrayList<String> loadedUris = new ArrayList<>();

        @Override
        public ClassLoader getClassLoader() {
            if (loader != null)
                return loader;
            return super.getClassLoader();
        }

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            if (savedInstanceState == null) {
                final ProgressBar progressBar = new ProgressBar(this);
                progressBar.setIndeterminate(true);
                setContentView(progressBar);
                new AsyncTask<Void, Void, Fragment>() {
                    @Override
                    protected Fragment doInBackground(Void... params) {
                        final File outputDir = getCacheDir();
                        try {

                            final String url = getIntent().getStringExtra(JAR_URL);

                            if (!loadedUris.contains(url)) {

                                final OkHttpClient client = new OkHttpClient();
                                Request request = new Request.Builder().url(url).build();
                                Response response = client.newCall(request).execute();
                                if (!response.isSuccessful())
                                    throw new IOException("Unexpected code " + response);

                                final File downloadedFile = File.createTempFile("temp", ".jar", outputDir);

                                BufferedSink sink = Okio.buffer(Okio.sink(downloadedFile));
                                sink.writeAll(response.body().source());
                                sink.close();

                                final File tmpDir = getDir("dex", 0);
                                final String libPath = downloadedFile.getPath();
                                loader = new DexClassLoader(libPath, tmpDir.getAbsolutePath(), null, getClassLoader());
                                loadedUris.add(url);
                            }
                            Class<?> classToLoad = getClassLoader().loadClass(getIntent().getStringExtra(FRAGMENT_CLASS_NAME));
                            return (Fragment) classToLoad.newInstance();

                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                        return null;
                    }

                    @Override
                    protected void onPostExecute(Fragment fragment) {
                        progressBar.setVisibility(View.GONE);
                        if (fragment != null) {
                            getSupportFragmentManager().beginTransaction().add(android.R.id.content, fragment, "frag").commit();
                        }
                    }
                }.execute();
            }
        }
    }
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="pl.selvin.fragmentloader">

    <uses-permission android:name="android.permission.INTERNET" />
    <application
        android:allowBackup="true"
        android:label="FragmentLoader"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".Activities$MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".Activities$GenericActivity" />

    </application>

</manifest>

build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.1"

    defaultConfig {
        applicationId "pl.selvin.fragmentloader"
        minSdkVersion 10
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    compile 'com.android.support:appcompat-v7:23.1.0'
    compile 'com.squareup.okhttp:okhttp:2.5.0'
}

colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#3F51B5</color>
    <color name="colorPrimaryDark">#303F9F</color>
    <color name="colorAccent">#FF4081</color>
</resources>

styles.xml

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.DarkActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

</resources>