Support installing the voices if the voice data signature has changed.

Makefile.am

 		espeak-data/phondata espeak-data/phonindex espeak-data/phontab \
 		espeak-data/*_dict espeak-data/voices
 
-android: android/res/raw/espeakdata.zip
+android/res/raw/espeakdata_version: android/res/raw/espeakdata.zip
+	sha1sum $< | awk '{ print $$1 }' > $@
+
+android: android/res/raw/espeakdata.zip android/res/raw/espeakdata_version
 
 ##### dictionaries:
 

android/res/raw/espeakdata_version

+6e7a49d1894b9915873b8bc066f35c65e155c31e

android/src/com/reecedunn/espeak/CheckVoiceData.java

 /*
+ * Copyright (C) 2012 Reece H. Dunn
  * Copyright (C) 2009 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
 import android.app.Activity;
 import android.content.Context;
 import android.content.Intent;
+import android.content.res.Resources.NotFoundException;
 import android.os.Bundle;
 import android.speech.tts.TextToSpeech;
 import android.speech.tts.TextToSpeech.Engine;
 import com.reecedunn.espeak.SpeechSynthesis.SynthReadyCallback;
 import com.reecedunn.espeak.SpeechSynthesis.Voice;
 
+import java.io.ByteArrayOutputStream;
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 
     /** Resources required for eSpeak to run correctly. */
     private static final String[] BASE_RESOURCES = {
-            "intonations", "phondata", "phonindex", "phontab", "en_dict", "voices/en/en-us"
+        "version",
+        "intonations",
+        "phondata",
+        "phonindex",
+        "phontab",
+        "en_dict",
+        "voices/en/en-us"
     };
 
     public static File getDataPath(Context context) {
         return true;
     }
 
+    public static String readContent(InputStream stream) throws IOException {
+        ByteArrayOutputStream content = new ByteArrayOutputStream();
+        int c = stream.read();
+        while (c != -1)
+        {
+            content.write((byte)c);
+            c = stream.read();
+        }
+        return content.toString();
+    }
+
+    public static boolean canUpgradeResources(Context context) {
+        try {
+            final String version = readContent(context.getResources().openRawResource(R.raw.espeakdata_version));
+            final String installedVersion = readContent(new FileInputStream(new File(getDataPath(context), "version")));
+            return !version.equals(installedVersion);
+        } catch (Exception e) {
+            return false;
+        }
+    }
+
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         ArrayList<String> availableLanguages = new ArrayList<String>();
         ArrayList<String> unavailableLanguages = new ArrayList<String>();
 
-        if (!hasBaseResources(this)) {
+        if (!hasBaseResources(this) || canUpgradeResources(this)) {
             if (!attemptedInstall) {
                 downloadVoiceData();
                 return;

android/src/com/reecedunn/espeak/DownloadVoiceData.java

                 // Make sure the output file is readable.
                 doChmod(outputFile);
             }
+
+            final String version = CheckVoiceData.readContent(mContext.getResources().openRawResource(R.raw.espeakdata_version));
+            final File outputFile = new File(mOutput, "espeak-data/version");
+            mExtractedFiles.add(outputFile);
+
+            final FileOutputStream outputStream = new FileOutputStream(outputFile);
+            outputStream.write(version.getBytes(), 0, version.length());
+            outputStream.close();
+            doChmod(outputFile);
         }
 
         private void removeExtractedFiles() {