Move //webapk to //chrome/android/webapk

webapk/shell_apk/src/org/chromium/webapk/shell_apk/DexLoader.java

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.webapk.shell_apk;
-
-import android.content.Context;
-import android.util.Log;
-
-import dalvik.system.BaseDexClassLoader;
-
-import java.io.File;
-import java.io.FileOutputStream;
-import java.io.InputStream;
-
-/**
- * Creates ClassLoader for .dex file in a remote Context's APK.
- */
-public class DexLoader {
-    private static final int BUFFER_SIZE = 16 * 1024;
-    private static final String TAG = "cr.DexLoader";
-
-    /**
-     * Creates ClassLoader for .dex file in {@link remoteContext}'s APK.
-     * @param remoteContext The context with the APK with the .dex file.
-     * @param dexName The name of the .dex file in the APK.
-     * @param canaryClassName Name of class in the .dex file. Used for testing the ClassLoader
-     *                        before returning it.
-     * @param remoteDexFile Location of already extracted .dex file from APK.
-     * @param localDexDir Writable directory for caching data to speed up future calls to
-     *                    {@link #load()}.
-     * @return The ClassLoader. Returns null on an error.
-     */
-    public static ClassLoader load(Context remoteContext, String dexName, String canaryClassName,
-            File remoteDexFile, File localDexDir) {
-        File localDexFile = new File(localDexDir, dexName);
-
-        // If {@link localDexFile} exists, technique #2 was previously used to create the
-        // ClassLoader. Skip right to the technique which worked last time.
-        if (remoteDexFile != null && remoteDexFile.exists() && !localDexFile.exists()) {
-            // Technique #1: At startup, Chrome code extracts the .dex file from its assets and
-            // guesses where DexClassLoader searches for the odex by default and puts the odex
-            // there. Try using the odex from Chrome's data directory.
-            ClassLoader loader = tryCreatingClassLoader(canaryClassName, remoteDexFile, null);
-            if (loader != null) {
-                return loader;
-            }
-        }
-
-        // Technique #2: Extract the .dex file from the remote context's APK. Create a
-        // ClassLoader from the extracted file.
-        if (!localDexFile.exists() || localDexFile.length() == 0) {
-            localDexDir.mkdirs();
-
-            InputStream inputStream;
-            try {
-                inputStream = remoteContext.getAssets().open(dexName);
-            } catch (Exception e) {
-                Log.w(TAG, "Could not extract dex from assets");
-                e.printStackTrace();
-                return null;
-            }
-            copyFromInputStream(inputStream, localDexFile);
-        }
-
-        File localOptimizedDir = new File(localDexDir, "optimized");
-        localOptimizedDir.mkdirs();
-
-        return tryCreatingClassLoader(canaryClassName, localDexFile, localOptimizedDir);
-    }
-
-    /**
-     * Deletes any files cached by {@link #load()}.
-     * @param localDexDir Cache directory passed to {@link #load()}.
-     */
-    public static void deleteCachedDexes(File localDexDir) {
-        deleteChildren(localDexDir);
-    }
-
-    /**
-     * Deletes all of a directory's children including subdirectories.
-     * @param parentDir Directory whose children should be deleted.
-     */
-    private static void deleteChildren(File parentDir) {
-        if (!parentDir.isDirectory()) {
-            return;
-        }
-
-        File[] files = parentDir.listFiles();
-        if (files != null) {
-            for (File file : files) {
-                deleteChildren(file);
-                if (!file.delete()) {
-                    Log.e(TAG, "Could not delete " + file.getPath());
-                }
-            }
-        }
-    }
-
-    /**
-     * Copies an InputStream to a file.
-     * @param inputStream
-     * @param outFile The destination file.
-     */
-    private static void copyFromInputStream(InputStream inputStream, File outFile) {
-        try (FileOutputStream outputStream = new FileOutputStream(outFile)) {
-            byte[] buffer = new byte[BUFFER_SIZE];
-            int count = 0;
-            while ((count = inputStream.read(buffer, 0, BUFFER_SIZE)) != -1) {
-                outputStream.write(buffer, 0, count);
-            }
-        } catch (Exception e) {
-        } finally {
-            try {
-                inputStream.close();
-            } catch (Exception e) {
-            }
-        }
-    }
-
-    /**
-     * Tries to create ClassLoader with the given .dex file and optimized dex directory.
-     * @param canaryClassName Name of class in the .dex file. Used for testing the ClassLoader
-     *                        before returning it.
-     * @param dexFile .dex file to create ClassLoader for.
-     * @param optimizedDir Directory for storing the optimized dex file. If null, an OS-defined
-     *                     path based on {@link dexFile} is used.
-     * @return The ClassLoader. Returns null on an error.
-     */
-    private static ClassLoader tryCreatingClassLoader(
-            String canaryClassName, File dexFile, File optimizedDir) {
-        try {
-            ClassLoader loader = new BaseDexClassLoader(
-                    dexFile.getPath(), optimizedDir, null, ClassLoader.getSystemClassLoader());
-            // Loading {@link canaryClassName} will throw an exception if the .dex file cannot be
-            // loaded.
-            loader.loadClass(canaryClassName);
-            return loader;
-        } catch (Exception e) {
-            String optimizedDirPath = (optimizedDir == null) ? null : optimizedDir.getPath();
-            Log.w(TAG, "Could not load dex from " + dexFile.getPath() + " with optimized directory "
-                            + optimizedDirPath);
-            e.printStackTrace();
-            return null;
-        }
-    }
-}