Refactor dynamic patching to use clearer naming and structure.

shell/platform/android/io/flutter/app/FlutterActivityDelegate.java

@@ -33,6 +33,7 @@
 import io.flutter.view.FlutterRunArguments;
 import io.flutter.view.FlutterView;
 
+import java.io.File;
 import java.util.ArrayList;
 
 /**
@@ -343,8 +344,9 @@ private void runBundle(String appBundlePath) {
         if (!flutterView.getFlutterNativeView().isApplicationRunning()) {
             FlutterRunArguments args = new FlutterRunArguments();
             ArrayList<String> bundlePaths = new ArrayList<>();
-            if (FlutterMain.getUpdateInstallationPath() != null) {
-                bundlePaths.add(FlutterMain.getUpdateInstallationPath());
+            if (FlutterMain.getResourceUpdater() != null) {
+                File patchFile = FlutterMain.getResourceUpdater().getPatch();
+                bundlePaths.add(patchFile.getPath());
             }
             bundlePaths.add(appBundlePath);
             args.bundlePaths = bundlePaths.toArray(new String[0]);

shell/platform/android/io/flutter/view/FlutterMain.java

@@ -360,8 +360,13 @@ public static String findAppBundlePath(Context applicationContext) {
         return appBundle.exists() ? appBundle.getPath() : null;
     }
 
-    public static String getUpdateInstallationPath() {
-        return sResourceUpdater == null ? null : sResourceUpdater.getUpdateInstallationPath();
+    /**
+     * Returns the main internal interface for the dynamic patching subsystem.
+     *
+     * If this is null, it means that dynamic patching is disabled in this app.
+     */
+    public static ResourceUpdater getResourceUpdater() {
+        return sResourceUpdater;
     }
 
     /**

shell/platform/android/io/flutter/view/ResourceExtractor.java

@@ -123,17 +123,6 @@ void waitForCompletion() {
         }
     }
 
-    boolean filesMatch() {
-        JSONObject updateManifest = readUpdateManifest();
-        if (!validateUpdateManifest(updateManifest)) {
-            updateManifest = null;
-        }
-
-        final File dataDir = new File(PathUtils.getDataDirectory(mContext));
-        final String timestamp = checkTimestamp(dataDir, updateManifest);
-        return (timestamp == null);
-    }
-
     private String[] getExistingTimestamps(File dataDir) {
         return dataDir.list(new FilenameFilter() {
             @Override
@@ -160,7 +149,6 @@ private void deleteFiles() {
         }
     }
 
-
     /// Returns true if successfully unpacked APK resources,
     /// otherwise deletes all resources and returns false.
     private boolean extractAPK(File dataDir) {
@@ -208,11 +196,12 @@ private boolean extractAPK(File dataDir) {
     /// Returns true if successfully unpacked update resources or if there is no update,
     /// otherwise deletes all resources and returns false.
     private boolean extractUpdate(File dataDir) {
-        if (FlutterMain.getUpdateInstallationPath() == null) {
+        ResourceUpdater resourceUpdater = FlutterMain.getResourceUpdater();
+        if (resourceUpdater == null) {
             return true;
         }
 
-        final File updateFile = new File(FlutterMain.getUpdateInstallationPath());
+        File updateFile = resourceUpdater.getPatch();
         if (!updateFile.exists()) {
             return true;
         }
@@ -298,11 +287,14 @@ private String checkTimestamp(File dataDir, JSONObject updateManifest) {
                 if (!buildNumber.equals(Long.toString(getVersionCode(packageInfo)))) {
                     Log.w(TAG, "Outdated update file for " + getVersionCode(packageInfo));
                 } else {
-                    final File updateFile = new File(FlutterMain.getUpdateInstallationPath());
+                    ResourceUpdater resourceUpdater = FlutterMain.getResourceUpdater();
+                    assert resourceUpdater != null;
+                    File patchFile = resourceUpdater.getPatch();
+                    assert patchFile.exists();
                     if (patchNumber != null) {
-                        expectedTimestamp += "-" + patchNumber + "-" + updateFile.lastModified();
+                        expectedTimestamp += "-" + patchNumber + "-" + patchFile.lastModified();
                     } else {
-                        expectedTimestamp += "-" + updateFile.lastModified();
+                        expectedTimestamp += "-" + patchFile.lastModified();
                     }
                 }
             }
@@ -365,11 +357,12 @@ private boolean validateUpdateManifest(JSONObject updateManifest) {
 
     /// Returns null if no update manifest is found.
     private JSONObject readUpdateManifest() {
-        if (FlutterMain.getUpdateInstallationPath() == null) {
+        ResourceUpdater resourceUpdater = FlutterMain.getResourceUpdater();
+        if (resourceUpdater == null) {
             return null;
         }
 
-        File updateFile = new File(FlutterMain.getUpdateInstallationPath());
+        File updateFile = resourceUpdater.getPatch();
         if (!updateFile.exists()) {
             return null;
         }

shell/platform/android/io/flutter/view/ResourceUpdater.java

@@ -58,23 +58,23 @@ enum InstallMode {
         IMMEDIATE
     }
 
-    private static class DownloadTask extends AsyncTask<String, String, Void> {
+    private class DownloadTask extends AsyncTask<String, String, Void> {
         @Override
-        protected Void doInBackground(String... args) {
+        protected Void doInBackground(String... unused) {
             try {
-                URL unresolvedURL = new URL(args[0]);
-                File localFile = new File(args[1]);
+                URL unresolvedURL = new URL(buildUpdateDownloadURL());
+                File localFile = getPatch();
 
                 long startMillis = new Date().getTime();
                 Log.i(TAG, "Checking for updates at " + unresolvedURL);
 
                 HttpURLConnection connection =
                         (HttpURLConnection)unresolvedURL.openConnection();
 
-                long lastModified = localFile.lastModified();
-                if (lastModified != 0) {
-                    Log.i(TAG, "Active update timestamp " + lastModified);
-                    connection.setIfModifiedSince(lastModified);
+                long lastDownloadTime = localFile.lastModified();
+                if (lastDownloadTime != 0) {
+                    Log.i(TAG, "Active update timestamp " + lastDownloadTime);
+                    connection.setIfModifiedSince(lastDownloadTime);
                 }
 
                 try (InputStream input = connection.getInputStream()) {
@@ -108,7 +108,6 @@ protected Void doInBackground(String... args) {
                         long totalMillis = new Date().getTime() - startMillis;
                         Log.i(TAG, "Update downloaded in " + totalMillis / 100 / 10. + "s");
 
-                        output.flush();
                         return null;
                     }
                 }
@@ -127,7 +126,7 @@ public ResourceUpdater(Context context) {
         this.context = context;
     }
 
-    public String getAPKVersion() {
+    private String getAPKVersion() {
         try {
             PackageManager packageManager = context.getPackageManager();
             PackageInfo packageInfo = packageManager.getPackageInfo(context.getPackageName(), 0);
@@ -138,11 +137,11 @@ public String getAPKVersion() {
         }
     }
 
-    public String getUpdateInstallationPath() {
-        return context.getFilesDir().toString() + "/patch.zip";
+    public File getPatch() {
+        return new File(context.getFilesDir().toString() + "/patch.zip");
     }
 
-    public String buildUpdateDownloadURL() {
+    private String buildUpdateDownloadURL() {
         Bundle metaData;
         try {
             metaData = context.getPackageManager().getApplicationInfo(
@@ -168,7 +167,7 @@ public String buildUpdateDownloadURL() {
         return uri.normalize().toString();
     }
 
-    public DownloadMode getDownloadMode() {
+    DownloadMode getDownloadMode() {
         Bundle metaData;
         try {
             metaData = context.getPackageManager().getApplicationInfo(
@@ -195,7 +194,7 @@ public DownloadMode getDownloadMode() {
         }
     }
 
-    public InstallMode getInstallMode() {
+    InstallMode getInstallMode() {
         Bundle metaData;
         try {
             metaData = context.getPackageManager().getApplicationInfo(
@@ -222,21 +221,21 @@ public InstallMode getInstallMode() {
         }
     }
 
-    public void startUpdateDownloadOnce() {
+    void startUpdateDownloadOnce() {
         if (downloadTask != null ) {
             return;
         }
         downloadTask = new DownloadTask();
-        downloadTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR,
-                buildUpdateDownloadURL(), getUpdateInstallationPath());
+        downloadTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
     }
 
-    public void waitForDownloadCompletion() {
+    void waitForDownloadCompletion() {
         if (downloadTask == null) {
             return;
         }
         try {
             downloadTask.get();
+            downloadTask = null;
         } catch (CancellationException e) {
             Log.w(TAG, "Download cancelled: " + e.getMessage());
             return;