Merge pull request #1425 from reicast/ac/dropbox

Update Dropbox API from 1.6 to 3.0

shell/android-studio/reicast/build.gradle

@@ -39,8 +39,6 @@ android {
         ndk {
             moduleName "dc"
                 abiFilters 'armeabi-v7a', 'x86'
-            moduleName "sexplay"
-                abiFilters 'armeabi-v7a', 'x86'
         }
     }
 
@@ -56,11 +54,13 @@ android {
     buildTypes {
         debug {
             debuggable true
+            minifyEnabled true
             zipAlignEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
         }
         release {
             debuggable false
-            minifyEnabled false
+            minifyEnabled true
             zipAlignEnabled true
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
             signingConfig signingConfigs.release
@@ -101,6 +101,7 @@ dependencies {
     implementation 'org.bouncycastle:bcprov-jdk16:1.46'
     implementation 'commons-io:commons-io:2.6'
     implementation 'org.apache.commons:commons-lang3:3.7'
+    implementation 'com.dropbox.core:dropbox-core-sdk:3.0.9'
     implementation ('com.googlecode.json-simple:json-simple:1.1.1') {
         exclude module: 'junit'
     }

shell/android-studio/reicast/proguard-rules.txt

@@ -0,0 +1,69 @@
+# This is a configuration file for ProGuard.
+# http://proguard.sourceforge.net/index.html#manual/usage.html
+# Optimizations: If you don't want to optimize, use the
+# proguard-android.txt configuration file instead of this one, which
+# turns off the optimization flags.  Adding optimization introduces
+# certain risks, since for example not all optimizations performed by
+# ProGuard works on all versions of Dalvik.  The following flags turn
+# off various optimizations known to have issues, but the list may not
+# be complete or up to date. (The "arithmetic" optimization can be
+# used if you are only targeting Android 2.0 or later.)  Make sure you
+# test thoroughly if you go this route.
+-optimizations !code/simplification/arithmetic,!code/simplification/cast,!field/*,!class/merging/*
+-optimizationpasses 5
+-allowaccessmodification
+-dontpreverify
+# The remainder of this file is identical to the non-optimized version
+# of the Proguard configuration file (except that the other file has
+# flags to turn off optimization).
+-dontusemixedcaseclassnames
+-dontskipnonpubliclibraryclasses
+-verbose
+-keepattributes *Annotation*
+# For native methods, see http://proguard.sourceforge.net/manual/examples.html#native
+-keepclasseswithmembernames class * {
+    native <methods>;
+}
+# keep setters in Views so that animations can still work.
+# see http://proguard.sourceforge.net/manual/examples.html#beans
+-keepclassmembers public class * extends android.view.View {
+   void set*(***);
+   *** get*();
+}
+# We want to keep methods in Activity that could be used in the XML attribute onClick
+-keepclassmembers class * extends android.app.Activity {
+   public void *(android.view.View);
+}
+# For enumeration classes, see http://proguard.sourceforge.net/manual/examples.html#enumerations
+-keepclassmembers enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
+-keepclassmembers class * implements android.os.Parcelable {
+  public static final android.os.Parcelable$Creator CREATOR;
+}
+-keepclassmembers class **.R$* {
+    public static <fields>;
+}
+
+-keep class com.reicast.** {*;}
+-keepclassmembers  class com.reicast.** {*;}
+
+# The support library contains references to newer platform versions.
+# Don't warn about those in case this app is linking against an older
+# platform version.  We know about them, and they are safe.
+-dontwarn android.support.**
+-dontwarn okio.**
+-dontwarn okhttp3.**
+-dontwarn com.squareup.okhttp.**
+-dontwarn com.google.appengine.**
+-dontwarn java.io.**
+-dontwarn java.nio.file.**
+-dontwarn javax.naming.**
+-dontwarn javax.servlet.**
+-dontwarn junit.textui.**
+
+-keepattributes Signature
+-keepattributes InnerClasses
+
+-keepattributes Exceptions,SourceFile,LineNumberTable

shell/android-studio/reicast/src/main/AndroidManifest.xml

@@ -101,11 +101,11 @@
             android:theme="@android:style/Theme.NoTitleBar.Fullscreen" >
         </activity>
         <activity
-            android:name="com.dropbox.client2.android.AuthActivity"
+            android:name="com.dropbox.core.android.AuthActivity"
             android:configChanges="orientation|keyboard"
-            android:launchMode="singleTask" >
+            android:launchMode="singleTask">
             <intent-filter>
-                <data android:scheme="db-7d7tw1t57sbzrj5" />
+                <data android:scheme="db-lowa9ps6h5k7zbo" />
                 <action android:name="android.intent.action.VIEW" />
                 <category android:name="android.intent.category.BROWSABLE" />
                 <category android:name="android.intent.category.DEFAULT" />

shell/android-studio/reicast/src/main/java/com/reicast/emulator/CloudFragment.java

@@ -1,350 +0,0 @@
-package com.reicast.emulator;
-
-/*
- *  File: CloudFragment.java
- *  Author: Luca D'Amico (Luca91)
- *  Last Edit: 11 May 2014
- *
- *  Reference: http://forums.reicast.com/index.php?topic=160.msg422
- */
-
-import android.app.AlertDialog;
-import android.content.Context;
-import android.content.DialogInterface;
-import android.content.SharedPreferences;
-import android.content.SharedPreferences.Editor;
-import android.os.AsyncTask;
-import android.os.Bundle;
-import android.os.Environment;
-import android.preference.PreferenceManager;
-import android.support.v4.app.Fragment;
-import android.util.Log;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.Button;
-import android.widget.Toast;
-
-import com.dropbox.client2.DropboxAPI;
-import com.dropbox.client2.DropboxAPI.Entry;
-import com.dropbox.client2.android.AndroidAuthSession;
-import com.dropbox.client2.exception.DropboxException;
-import com.dropbox.client2.session.AccessTokenPair;
-import com.dropbox.client2.session.AppKeyPair;
-import com.dropbox.client2.session.TokenPair;
-import com.reicast.emulator.config.Config;
-
-import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileNotFoundException;
-import java.io.FileOutputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.util.concurrent.ExecutionException;
-
-
-public class CloudFragment extends Fragment {
-
-	Button uploadBtn;
-	Button downloadBtn;
-	AlertDialog.Builder confirmDialog = null;
-	boolean actionRequired=false;
-	public String task = "";
-	DropBoxClient client = null;
-	private String home_directory;
-
-	String[] vmus = {"vmu_save_A1.bin","vmu_save_A2.bin",
-			"vmu_save_B1.bin","vmu_save_B2.bin",
-			"vmu_save_C1.bin","vmu_save_C2.bin",
-			"vmu_save_D1.bin","vmu_save_D2.bin"};
-
-	@Override
-	public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
-		return inflater.inflate(R.layout.cloud_fragment, container, false);
-	}
-
-	@Override
-	public void onViewCreated(View view, Bundle savedInstanceState) {
-		SharedPreferences mPrefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
-		home_directory = mPrefs.getString(Config.pref_home,
-				Environment.getExternalStorageDirectory().getAbsolutePath());
-		buttonListener();
-		confirmDialog = new AlertDialog.Builder(getActivity());
-		setClient();
-	}
-
-	public void setClient(){
-		if(client==null)
-			client = new DropBoxClient(getActivity());
-	}
-
-
-	public void buttonListener() {
-		uploadBtn = (Button) getView().findViewById(R.id.uploadBtn);
-		uploadBtn.setOnClickListener(new View.OnClickListener() {
-			@Override
-			public void onClick(View arg0) {
-				confirmDialog.setMessage(R.string.uploadWarning);
-				confirmDialog.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
-					public void onClick(DialogInterface dialog, int which) {
-						setClient();
-						task = "Upload";
-						client.startLogin();
-						actionRequired = true;
-					}
-				});
-				confirmDialog.setNegativeButton(R.string.cancel, null);
-				confirmDialog.show();
-
-			}
-		});
-
-
-		downloadBtn = (Button) getView().findViewById(R.id.downloadBtn);
-		downloadBtn.setOnClickListener(new View.OnClickListener() {
-			@Override
-			public void onClick(View arg0) {
-				confirmDialog.setMessage(R.string.downloadWarning);
-				confirmDialog.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
-					public void onClick(DialogInterface dialog, int which) {
-						setClient();
-						task = "Download";
-						client.startLogin();
-						actionRequired = true;
-					}
-				});
-				confirmDialog.setNegativeButton(R.string.cancel, null);
-				confirmDialog.show();
-			}
-		});
-	}
-
-
-	@Override
-	public void onResume(){
-		super.onResume();
-		if (client.mDBApi != null) {
-			if (client.mDBApi.getSession().authenticationSuccessful()) {
-				try {
-					client.mDBApi.getSession().finishAuthentication();
-					TokenPair tokens = client.mDBApi.getSession(). getAccessTokenPair();
-					if(tokens == null)
-						Toast.makeText(getActivity(), "Failed to save session token!", Toast.LENGTH_SHORT).show();
-					else
-						client.storeKeys(tokens.key, tokens.secret);
-				} catch (IllegalStateException e) {
-					Log.i("Dropbox", "Error authenticating", e);
-				}
-			}
-			if(actionRequired){
-				for(int k=0;k<vmus.length;k++){
-					String result = "";
-					try {
-						String vmuPath = home_directory+"/"+vmus[k];
-						File vmu = new File(vmuPath);
-						if(vmu.exists() || task.equals("Download") ){
-							result = new netOperation(client, home_directory).execute(
-									task,vmuPath,vmus[k]).get();
-						}
-						else{
-							result = "Ok"; // The result is still ok, because the vmu bin doesn't exist ;)
-							Toast.makeText(getActivity(), vmus[k]+ " doesn't exist, skipping it!",
-									Toast.LENGTH_SHORT).show();
-						}
-					} catch (InterruptedException e) {
-						e.printStackTrace();
-					} catch (ExecutionException e) {
-						e.printStackTrace();
-					}
-					if(result.equals("Ok"))
-						Toast.makeText(getActivity(), "Task Completed!", Toast.LENGTH_SHORT).show();
-					else
-						Toast.makeText(getActivity(), "Task Failed!", Toast.LENGTH_SHORT).show();
-				}
-			}
-			actionRequired = false;
-		}
-	}
-
-
-}
-
-
-class DropBoxClient {
-
-	Context context;
-
-	final static private String APP_KEY = "7d7tw1t57sbzrj5";
-	final static private String APP_SECRET = "5xxqa2uctousyi2";
-
-	public DropboxAPI<AndroidAuthSession> mDBApi;
-	AndroidAuthSession session;
-
-	public DropBoxClient(Context context){
-		this.context = context;
-		session = buildSession();
-		mDBApi = new DropboxAPI<AndroidAuthSession>(session);
-	}
-
-	public void startLogin(){
-		mDBApi.getSession().startOAuth2Authentication(context);
-	}
-
-	public String[] getKeys() {
-		SharedPreferences prefs = context.getSharedPreferences("ReicastVMUUploader", 0);
-		String key = prefs.getString("DBoxKey", null);
-		String secret = prefs.getString("DBoxSecret", null);
-		if (key != null && secret != null) {
-			String[] ret = new String[2];
-			ret[0] = key;
-			ret[1] = secret;
-			return ret;
-		} else {
-			return null;
-		}
-	}
-
-
-
-	public void storeKeys(String key, String secret) {
-		SharedPreferences prefs = context.getSharedPreferences("ReicastVMUUploader", 0);
-		Editor edit = prefs.edit();
-		edit.putString("DBoxKey", key);
-		edit.putString("DBoxSecret", secret);
-		edit.apply();
-	}
-
-	private AndroidAuthSession buildSession() {
-		AppKeyPair appKeyPair = new AppKeyPair(APP_KEY, APP_SECRET);
-		AndroidAuthSession session;
-
-		String[] stored = getKeys();
-		if (stored != null) {
-			AccessTokenPair accessToken = new AccessTokenPair(stored[0], stored[1]);
-			session = new AndroidAuthSession(appKeyPair, accessToken);
-		} else {
-			session = new AndroidAuthSession(appKeyPair);
-		}
-
-		return session;
-	}
-
-}
-
-class netOperation extends AsyncTask<String, Void, String> {
-
-	DropBoxClient client = null;
-	private String home_directory;
-
-	public netOperation(DropBoxClient client, String home_directory){
-		this.client = client;
-		this.home_directory = home_directory;
-	}
-
-	public boolean uploadFile(String filePath, String fileName) {
-		File file = new File(filePath);
-		FileInputStream inputStream = null;
-		try {
-			inputStream = new FileInputStream(file);
-		} catch (FileNotFoundException e) {
-			e.printStackTrace();
-		}
-
-		DropboxAPI.Entry response = null;
-		try {
-			response = client.mDBApi.putFileOverwrite("/"+fileName, inputStream, file.length(), null);
-		} catch (DropboxException e) {
-			e.printStackTrace();
-		}
-		Log.i("FileInfos", "The uploaded file's rev is: "+ response);
-		return true;
-	}
-
-	public boolean downloadFile(String filePath, String fileName) {
-		DropboxAPI.DropboxFileInfo info = null;
-		try {
-			Entry remoteFile = client.mDBApi.metadata("/"+fileName, 1, null, false, null);
-			if((remoteFile.rev != null) && (remoteFile.bytes > 0)){ // Avoid to download 0 bytes vmus!
-				File file = new File(filePath);
-				if(file.exists())
-					createBackupOfVmu(fileName);
-				FileOutputStream out = null;
-				try {
-					out = new FileOutputStream(file);
-				} catch (FileNotFoundException e) {
-					e.printStackTrace();
-				}
-				info = client.mDBApi.getFile("/"+fileName,null,out,null);
-			}
-		} catch (DropboxException e) {
-			e.printStackTrace();
-		}
-		Log.i("FileInfos", "The downloaded file's rev is: "+ info);
-		return true;
-	}
-
-
-	@Override
-	protected void onPostExecute(String result) {
-
-	}
-
-	@Override
-	protected String doInBackground(String... strings) {
-		if(strings[0].equals("Upload")){
-			if(uploadFile(strings[1],strings[2]))
-				return "Ok";
-			else
-				return "No";
-		}
-		else if(strings[0].equals("Download")){
-			if(downloadFile(strings[1],strings[2]))
-				return "Ok";
-			else
-				return "No";
-		}
-		else
-			return "Unknown";
-	}
-
-	@Override
-	protected void onPreExecute() {}
-
-	@Override
-	protected void onProgressUpdate(Void... values) {}
-
-
-	void  createBackupOfVmu(String vmuName){
-		File backupDir = new File(home_directory+"/VmuBackups/");
-		if(!backupDir.exists()) {
-			backupDir.mkdirs();
-		}
-
-		File source = new File(home_directory+"/"+vmuName);
-		File destination = new File(home_directory+"/VmuBackups/"+vmuName);
-		if(!destination.exists()) {
-			try {
-				destination.createNewFile();
-			} catch (IOException e) {
-				e.printStackTrace();
-			}
-		}
-		try {
-			InputStream in = new FileInputStream(source);
-			OutputStream out = new FileOutputStream(destination);
-			byte[] buffer = new byte[1024];
-			int length;
-			while ((length = in.read(buffer)) > 0){
-				out.write(buffer, 0, length);
-			}
-			in.close();
-			out.close();
-		} catch (FileNotFoundException e) {
-			e.printStackTrace();
-		} catch (IOException e) {
-			e.printStackTrace();
-		}
-	}
-
-}

shell/android-studio/reicast/src/main/java/com/reicast/emulator/FileBrowser.java

@@ -194,6 +194,11 @@ public class FileBrowser extends Fragment {
 			if (buttons != null && buttons.exists()) {
 				in = new FileInputStream(buttons);
 			} else if (!file.exists() || file.length() == 0) {
+				try {
+					file.createNewFile();
+				} catch (Exception e) {
+					// N+ files be broken
+				}
 				in = getActivity().getAssets().open("buttons.png");
 			}
 			if (in != null) {
@@ -321,17 +326,7 @@ public class FileBrowser extends Fragment {
 			((TextView) childview.findViewById(R.id.item_name)).setText(R.string.boot_bios);
 			ImageView icon = (ImageView) childview.findViewById(R.id.item_icon);
 			icon.setImageResource(R.mipmap.disk_bios);
-			int app_theme = mPrefs.getInt(Config.pref_app_theme, 0);
+			configureTheme(childview, true);
-			if (app_theme == 7) {
-				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-						ContextCompat.getColor(getActivity(), R.color.colorDreamTint)));
-			} else if (app_theme == 1) {
-				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-						ContextCompat.getColor(getActivity(), R.color.colorBlueTint)));
-			} else {
-				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-						ContextCompat.getColor(getActivity(), R.color.colorDarkTint)));
-			}
 
 			childview.setTag(null);
 
@@ -352,17 +347,7 @@ public class FileBrowser extends Fragment {
 			((TextView) childview.findViewById(R.id.item_name)).setText(R.string.clear_search);
 			ImageView icon = (ImageView) childview.findViewById(R.id.item_icon);
 			icon.setImageResource(R.mipmap.disk_unknown);
-			int app_theme = mPrefs.getInt(Config.pref_app_theme, 0);
+			configureTheme(childview, true);
-			if (app_theme == 7) {
-				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-						ContextCompat.getColor(getActivity(), R.color.colorDreamTint)));
-			} else if (app_theme == 1) {
-				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-						ContextCompat.getColor(getActivity(), R.color.colorBlueTint)));
-			} else {
-				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-						ContextCompat.getColor(getActivity(), R.color.colorDarkTint)));
-			}
 
 			childview.setTag(null);
 
@@ -433,6 +418,7 @@ public class FileBrowser extends Fragment {
 						}
 					}
 				});
+		configureTheme(childview, false);
 		list.addView(childview);
 		xmlParser.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, game.getName());
 	}
@@ -499,18 +485,6 @@ public class FileBrowser extends Fragment {
 					final View childview = browser.get().getActivity().getLayoutInflater().inflate(
 							R.layout.browser_fragment_item, null, false);
 
-					int app_theme = browser.get().mPrefs.getInt(Config.pref_app_theme, 0);
-					if (app_theme == 7) {
-						childview.findViewById(R.id.childview)
-								.setBackgroundResource(R.drawable.game_selector_dream);
-					} else if (app_theme == 1) {
-						childview.findViewById(R.id.childview)
-								.setBackgroundResource(R.drawable.game_selector_blue);
-					} else {
-						childview.findViewById(R.id.childview)
-								.setBackgroundResource(R.drawable.game_selector_dark);
-					}
-
 					if (file == null) {
 						((TextView) childview.findViewById(R.id.item_name)).setText(R.string.folder_select);
 					} else if (file == parent)
@@ -522,17 +496,7 @@ public class FileBrowser extends Fragment {
 					icon.setImageResource(file == null
 							? R.drawable.ic_settings: file.isDirectory()
 							? R.drawable.ic_folder_black_24dp : R.drawable.disk_unknown);
-
+					browser.get().configureTheme(childview, true);
-					if (app_theme == 7) {
-						ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-								ContextCompat.getColor(browser.get().getActivity(), R.color.colorDreamTint)));
-					} else if (app_theme == 1) {
-						ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-								ContextCompat.getColor(browser.get().getActivity(), R.color.colorBlueTint)));
-					} else {
-						ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
-								ContextCompat.getColor(browser.get().getActivity(), R.color.colorDarkTint)));
-					}
 
 					childview.setTag(file);
 
@@ -616,6 +580,30 @@ public class FileBrowser extends Fragment {
         }
     }
 
+	private void configureTheme(View childview, boolean useTint) {
+		int app_theme = mPrefs.getInt(Config.pref_app_theme, 0);
+		ImageView icon = (ImageView) childview.findViewById(R.id.item_icon);
+		if (app_theme == 7) {
+			childview.findViewById(R.id.childview)
+					.setBackgroundResource(R.drawable.game_selector_dream);
+			if (useTint)
+				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
+						ContextCompat.getColor(getActivity(), R.color.colorDreamTint)));
+		} else if (app_theme == 1) {
+			childview.findViewById(R.id.childview)
+					.setBackgroundResource(R.drawable.game_selector_blue);
+			if (useTint)
+				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
+						ContextCompat.getColor(getActivity(), R.color.colorBlueTint)));
+		} else {
+			childview.findViewById(R.id.childview)
+					.setBackgroundResource(R.drawable.game_selector_dark);
+			if (useTint)
+				ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
+						ContextCompat.getColor(getActivity(), R.color.colorDarkTint)));
+		}
+	}
+
 	private void showToastMessage(String message, int duration) {
 		ConstraintLayout layout = (ConstraintLayout) getActivity().findViewById(R.id.mainui_layout);
 		Snackbar snackbar = Snackbar.make(layout, message, duration);

shell/android-studio/reicast/src/main/java/com/reicast/emulator/MainActivity.java

@@ -20,7 +20,6 @@ import android.support.design.widget.NavigationView;
 import android.support.design.widget.Snackbar;
 import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.Fragment;
-import android.support.v4.app.FragmentTransaction;
 import android.support.v4.view.GravityCompat;
 import android.support.v4.widget.DrawerLayout;
 import android.support.v7.app.AppCompatActivity;
@@ -41,6 +40,7 @@ import com.reicast.emulator.config.InputFragment;
 import com.reicast.emulator.config.OptionsFragment;
 import com.reicast.emulator.config.PGConfigFragment;
 import com.reicast.emulator.debug.GenerateLogs;
+import com.reicast.emulator.cloud.CloudFragment;
 import com.reicast.emulator.emu.JNIdc;
 
 import java.lang.Thread.UncaughtExceptionHandler;

shell/android-studio/reicast/src/main/java/com/reicast/emulator/XMLParser.java

@@ -227,12 +227,15 @@ public class XMLParser extends AsyncTask<String, Integer, String> {
 		icon.setImageDrawable(game_icon);
 		int app_theme = mPrefs.getInt(Config.pref_app_theme, 0);
 		if (app_theme == 7) {
+			childview.get().setBackgroundResource(R.drawable.game_selector_dream);
 			ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
 					ContextCompat.getColor(mContext.get(), R.color.colorDreamTint)));
 		} else if (app_theme == 1) {
+			childview.get().setBackgroundResource(R.drawable.game_selector_blue);
 			ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
 					ContextCompat.getColor(mContext.get(), R.color.colorBlueTint)));
 		} else {
+			childview.get().setBackgroundResource(R.drawable.game_selector_dark);
 			ImageViewCompat.setImageTintList(icon, ColorStateList.valueOf(
 					ContextCompat.getColor(mContext.get(), R.color.colorDarkTint)));
 		}

shell/android-studio/reicast/src/main/java/com/reicast/emulator/cloud/CloudFragment.java

@@ -0,0 +1,432 @@
+package com.reicast.emulator.cloud;
+
+/*
+ *  Author: Luca D'Amico (Luca91)
+ *  Rewrite: AbandonedCart
+ *  Last Edit: 02 Oct 2018
+ *  Reference: http://forums.reicast.com/index.php?topic=160.msg422
+ */
+
+import android.app.AlertDialog;
+import android.app.ProgressDialog;
+import android.content.Context;
+import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.net.Uri;
+import android.os.AsyncTask;
+import android.os.Bundle;
+import android.os.Environment;
+import android.preference.PreferenceManager;
+import android.support.v4.app.Fragment;
+import android.util.Log;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.Toast;
+
+import com.dropbox.core.DbxException;
+import com.dropbox.core.android.Auth;
+import com.dropbox.core.v2.DbxClientV2;
+import com.dropbox.core.v2.files.FileMetadata;
+import com.dropbox.core.v2.files.ListFolderResult;
+import com.dropbox.core.v2.files.Metadata;
+import com.dropbox.core.v2.files.WriteMode;
+import com.reicast.emulator.R;
+import com.reicast.emulator.config.Config;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.lang.ref.WeakReference;
+
+
+public class CloudFragment extends Fragment {
+
+    private final static String APP_KEY = "lowa9ps6h5k7zbo";
+	private String mPath = ""; // Dropbox folder
+
+	Button uploadBtn;
+	Button downloadBtn;
+	AlertDialog.Builder confirmDialog = null;
+	private String home_directory;
+
+	String[] vmus = {"vmu_save_A1.bin", "vmu_save_A2.bin",
+			"vmu_save_B1.bin", "vmu_save_B2.bin",
+			"vmu_save_C1.bin", "vmu_save_C2.bin",
+			"vmu_save_D1.bin", "vmu_save_D2.bin"};
+
+	@Override
+	public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
+		return inflater.inflate(R.layout.cloud_fragment, container, false);
+	}
+
+	@Override
+	public void onViewCreated(View view, Bundle savedInstanceState) {
+		SharedPreferences mPrefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
+		home_directory = mPrefs.getString(Config.pref_home,
+				Environment.getExternalStorageDirectory().getAbsolutePath());
+		buttonListener();
+		confirmDialog = new AlertDialog.Builder(getActivity());
+	}
+
+	@Override
+	public void onResume() {
+		super.onResume();
+		SharedPreferences mPrefs = PreferenceManager.getDefaultSharedPreferences(getActivity());
+		String accessToken = mPrefs.getString("access-token", null);
+		if (accessToken == null) {
+			accessToken = Auth.getOAuth2Token();
+			if (accessToken != null) {
+				mPrefs.edit().putString("access-token", accessToken).apply();
+				DbxClientFactory.init(accessToken);
+			}
+		} else {
+			DbxClientFactory.init(accessToken);
+		}
+	}
+
+	public void buttonListener() {
+		Auth.startOAuth2Authentication(getActivity(), APP_KEY);
+		uploadBtn = (Button) getView().findViewById(R.id.uploadBtn);
+		uploadBtn.setOnClickListener(new View.OnClickListener() {
+			@Override
+			public void onClick(View arg0) {
+				confirmDialog.setMessage(R.string.uploadWarning);
+				confirmDialog.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+					public void onClick(DialogInterface dialog, int which) {
+						getPathForFiles("Upload");
+					}
+				});
+				confirmDialog.setNegativeButton(R.string.cancel, null);
+				confirmDialog.show();
+
+			}
+		});
+
+
+		downloadBtn = (Button) getView().findViewById(R.id.downloadBtn);
+		downloadBtn.setOnClickListener(new View.OnClickListener() {
+			@Override
+			public void onClick(View arg0) {
+				confirmDialog.setMessage(R.string.downloadWarning);
+				confirmDialog.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener() {
+					public void onClick(DialogInterface dialog, int which) {
+						getPathForFiles("Download");
+					}
+				});
+				confirmDialog.setNegativeButton(R.string.cancel, null);
+				confirmDialog.show();
+			}
+		});
+	}
+
+	private void uploadFile(String filePath) {
+		final ProgressDialog dialog = new ProgressDialog(getActivity());
+		dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
+		dialog.setCancelable(false);
+		dialog.setMessage("Uploading");
+		dialog.show();
+
+		try {
+			new UploadFileTask(getActivity(), DbxClientFactory.getClient(), new UploadFileTask.Callback() {
+				@Override
+				public void onUploadComplete(FileMetadata result) {
+					dialog.dismiss();
+				}
+
+				@Override
+				public void onError(Exception e) {
+					dialog.dismiss();
+
+					Log.e(getActivity().getLocalClassName(), "Failed to upload file.", e);
+					Toast.makeText(getActivity(),
+							"Failed to upload file", Toast.LENGTH_SHORT).show();
+				}
+			}).execute(filePath, mPath);
+		} catch (IllegalStateException s) {
+			dialog.dismiss();
+			Log.e(getActivity().getLocalClassName(), "Failed to upload file.", s);
+			Toast.makeText(getActivity(),
+					"Failed to upload file", Toast.LENGTH_SHORT).show();
+		}
+	}
+
+	private void retrieveFiles(final String vmu) {
+		final ProgressDialog dialog = new ProgressDialog(getActivity());
+		dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
+		dialog.setCancelable(false);
+		dialog.setMessage("Loading");
+		dialog.show();
+
+		try {
+			new ListFolderTask(DbxClientFactory.getClient(), new ListFolderTask.Callback() {
+				@Override
+				public void onDataLoaded(ListFolderResult result) {
+					dialog.dismiss();
+					for (Metadata item : result.getEntries()) {
+						if (item.getName().equals(vmu)) {
+							if (item instanceof FileMetadata) {
+								downloadFile((FileMetadata) item);
+							}
+						}
+					}
+				}
+
+				@Override
+				public void onError(Exception e) {
+					dialog.dismiss();
+
+					Log.e(getActivity().getLocalClassName(), "Failed to list folder.", e);
+					Toast.makeText(getActivity(),
+							"Failed to list folder", Toast.LENGTH_SHORT).show();
+				}
+			}).execute(mPath);
+		} catch (IllegalStateException s) {
+			dialog.dismiss();
+			Log.e(getActivity().getLocalClassName(), "Failed to list folder.", s);
+			Toast.makeText(getActivity(),
+					"Failed to list folder", Toast.LENGTH_SHORT).show();
+		}
+	}
+
+	private void downloadFile(FileMetadata file) {
+		final ProgressDialog dialog = new ProgressDialog(getActivity());
+		dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
+		dialog.setCancelable(false);
+		dialog.setMessage("Downloading");
+		dialog.show();
+
+		try {
+			new DownloadFileTask(this, DbxClientFactory.getClient(), new DownloadFileTask.Callback() {
+				@Override
+				public void onDownloadComplete(File result) {
+					dialog.dismiss();
+				}
+
+				@Override
+				public void onError(Exception e) {
+					dialog.dismiss();
+
+					Log.e(getActivity().getLocalClassName(), "Failed to download file.", e);
+					Toast.makeText(getActivity(),
+							"Failed to download file\n" + e, Toast.LENGTH_SHORT).show();
+				}
+			}).execute(file);
+		} catch (IllegalStateException s) {
+			dialog.dismiss();
+			Log.e(getActivity().getLocalClassName(), "Failed to download file.", s);
+			Toast.makeText(getActivity(),
+					"Failed to download file", Toast.LENGTH_SHORT).show();
+		}
+	}
+
+	static class UploadFileTask extends AsyncTask<String, Void, FileMetadata> {
+
+		private WeakReference<Context> mContext;
+		private final DbxClientV2 mDbxClient;
+		private final Callback mCallback;
+		private Exception mException;
+
+		public interface Callback {
+			void onUploadComplete(FileMetadata result);
+			void onError(Exception e);
+		}
+
+		UploadFileTask(Context context, DbxClientV2 dbxClient, Callback callback) {
+			mContext = new WeakReference<>(context);
+			mDbxClient = dbxClient;
+			mCallback = callback;
+		}
+
+		@Override
+		protected void onPostExecute(FileMetadata result) {
+			super.onPostExecute(result);
+			if (mException != null) {
+				mCallback.onError(mException);
+			} else if (result == null) {
+				mCallback.onError(null);
+			} else {
+				mCallback.onUploadComplete(result);
+			}
+		}
+
+		@Override
+		protected FileMetadata doInBackground(String... params) {
+			File localFile = new File(params[0]);
+			String remoteFolderPath = params[1];
+
+			// Note - does not verify a valid dropbox file name
+			String remoteFileName = localFile.getName();
+
+			try {
+				InputStream inputStream = new FileInputStream(localFile);
+				return mDbxClient.files().uploadBuilder(
+						remoteFolderPath + "/" + remoteFileName)
+						.withMode(WriteMode.OVERWRITE)
+						.uploadAndFinish(inputStream);
+			} catch (DbxException | IOException e) {
+				mException = e;
+			}
+
+			return null;
+		}
+	}
+
+	static class ListFolderTask extends AsyncTask<String, Void, ListFolderResult> {
+
+		private final DbxClientV2 mDbxClient;
+		private final Callback mCallback;
+		private Exception mException;
+
+		public interface Callback {
+			void onDataLoaded(ListFolderResult result);
+			void onError(Exception e);
+		}
+
+		ListFolderTask(DbxClientV2 dbxClient, Callback callback) {
+			mDbxClient = dbxClient;
+			mCallback = callback;
+		}
+
+		@Override
+		protected void onPostExecute(ListFolderResult result) {
+			super.onPostExecute(result);
+
+			if (mException != null) {
+				mCallback.onError(mException);
+			} else {
+				mCallback.onDataLoaded(result);
+			}
+		}
+
+		@Override
+		protected ListFolderResult doInBackground(String... params) {
+			try {
+				return mDbxClient.files().listFolder(params[0]);
+			} catch (DbxException e) {
+				mException = e;
+			}
+
+			return null;
+		}
+	}
+
+	static class DownloadFileTask extends AsyncTask<FileMetadata, Void, File> {
+
+		private WeakReference<CloudFragment> mCloud;
+		private final DbxClientV2 mDbxClient;
+		private final Callback mCallback;
+		private Exception mException;
+
+		public interface Callback {
+			void onDownloadComplete(File result);
+			void onError(Exception e);
+		}
+
+		DownloadFileTask(CloudFragment context, DbxClientV2 dbxClient, Callback callback) {
+            mCloud = new WeakReference<>(context);
+			mDbxClient = dbxClient;
+			mCallback = callback;
+		}
+
+		@Override
+		protected void onPostExecute(File result) {
+			super.onPostExecute(result);
+			if (mException != null) {
+				mCallback.onError(mException);
+			} else {
+				mCallback.onDownloadComplete(result);
+			}
+		}
+
+		@Override
+		protected File doInBackground(FileMetadata... params) {
+			FileMetadata metadata = params[0];
+			try {
+				File path = new File(mCloud.get().home_directory);
+				File file = new File(path, metadata.getName());
+
+				// Make sure the Downloads directory exists.
+				if (!path.exists()) {
+					if (!path.mkdirs()) {
+						mException = new RuntimeException("Unable to create directory: " + path);
+					}
+				} else if (!path.isDirectory()) {
+					mException = new IllegalStateException("Download path is not a directory: " + path);
+					return null;
+				}
+
+				// Download the file.
+				OutputStream outputStream = new FileOutputStream(file);
+				mDbxClient.files().download(metadata.getPathLower(), metadata.getRev())
+						.download(outputStream);
+
+				// Tell android about the file
+				Intent intent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
+				intent.setData(Uri.fromFile(file));
+				mCloud.get().getActivity().sendBroadcast(intent);
+
+				return file;
+			} catch (DbxException | IOException e) {
+				mException = e;
+			}
+
+			return null;
+		}
+	}
+
+	private void getPathForFiles(String task) {
+		for (String vmu : vmus) {
+			File vmuFile = new File(home_directory, vmu);
+			if (task.equals("Download")) {
+				if (vmuFile.exists())
+					createBackupOfVmu(vmuFile.getName());
+				else
+                    retrieveFiles(vmuFile.getName());
+			}
+			if (task.equals("Upload")) {
+				if (vmuFile.exists())
+					uploadFile(vmuFile.toString());
+			}
+		}
+	}
+
+	void createBackupOfVmu(String vmuName) {
+		File backupDir = new File(home_directory, "vmu_backup");
+		if (!backupDir.exists()) {
+			backupDir.mkdirs();
+		}
+
+		File source = new File(home_directory, vmuName);
+		File destination = new File(home_directory, "vmu_backup/" + vmuName);
+		if (!destination.exists()) {
+			try {
+				destination.createNewFile();
+			} catch (IOException e) {
+				e.printStackTrace();
+			}
+		}
+		try {
+			InputStream in = new FileInputStream(source);
+			OutputStream out = new FileOutputStream(destination);
+			byte[] buffer = new byte[1024];
+			int length;
+			while ((length = in.read(buffer)) > 0) {
+				out.write(buffer, 0, length);
+			}
+			in.close();
+			out.close();
+		} catch (FileNotFoundException e) {
+			e.printStackTrace();
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+        retrieveFiles(vmuName);
+	}
+}

shell/android-studio/reicast/src/main/java/com/reicast/emulator/cloud/DbxClientFactory.java

@@ -0,0 +1,32 @@
+package com.reicast.emulator.cloud;
+
+import com.dropbox.core.DbxRequestConfig;
+import com.dropbox.core.http.StandardHttpRequestor;
+import com.dropbox.core.v2.DbxClientV2;
+
+/**
+ * Singleton instance of {@link DbxClientV2} and friends
+ */
+public class DbxClientFactory {
+
+    private static DbxClientV2 sDbxClient;
+
+    public static void init(String accessToken) {
+        if (sDbxClient == null) {
+            StandardHttpRequestor requestor = new StandardHttpRequestor(
+                    StandardHttpRequestor.Config.DEFAULT_INSTANCE);
+            DbxRequestConfig requestConfig = DbxRequestConfig
+                    .newBuilder("ReicastCloud")
+                    .withHttpRequestor(requestor).build();
+
+            sDbxClient = new DbxClientV2(requestConfig, accessToken);
+        }
+    }
+
+    public static DbxClientV2 getClient() {
+        if (sDbxClient == null) {
+            throw new IllegalStateException("Client not initialized.");
+        }
+        return sDbxClient;
+    }
+}