1，apk中的classes2.dex ..classesN.dex... 等文件被解析出来分别存储在 /data/data/packagename/files/secondary-dex/ 下 的zip文件中(这一过程只在app安装后第一次启动时进行）；
classesN.dex 对应 packageName.classesN.zip , 当然每个zip文件里只有一个zipEntry， 名字是 classes.dex（其实就是apk 里的 classesN.dex）;
2，解析出来的所有的zip文件保存在一个 files 数组中， 这个数组最终合并到 ClassLoader（DexClassLoader）的 pathList 的 dexElements 数组（根类路径）。
/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package android.support.multidex;import android.app.Application;import android.content.Context;import android.content.pm.ApplicationInfo;import android.content.pm.PackageManager;import android.content.pm.PackageManager.NameNotFoundException;import android.os.Build;import android.util.Log;import dalvik.system.DexFile;import java.io.File;import java.io.IOException;import java.lang.reflect.Array;import java.lang.reflect.Field;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.Arrays;import java.util.HashSet;import java.util.List;import java.util.ListIterator;import java.util.Set;import java.util.regex.Matcher;import java.util.regex.Pattern;import java.util.zip.ZipFile;/** * Monkey patches {@link Context#getClassLoader() the application context class * loader} in order to load classes from more than one dex file. The primary * {@code classes.dex} must contain the classes necessary for calling this * class methods. Secondary dex files named classes2.dex, classes3.dex... found * in the application apk will be added to the classloader after first call to * {@link #install(Context)}. * * * This library provides compatibility for platforms with API level 4 through 20. This library does * nothing on newer versions of the platform which provide built-in support for secondary dex files. */public final class MultiDex { static final String TAG = "MultiDex"; private static final String SECONDARY_FOLDER_NAME = "secondary-dexes"; private static final int MAX_SUPPORTED_SDK_VERSION = 20; private static final int MIN_SDK_VERSION = 4; private static final int VM_WITH_MULTIDEX_VERSION_MAJOR = 2; private static final int VM_WITH_MULTIDEX_VERSION_MINOR = 1; private static final Set installedApk = new HashSet (); private static final boolean IS_VM_MULTIDEX_CAPABLE = isVMMultidexCapable(System.getProperty("java.vm.version")); private MultiDex() {} /** * Patches the application context class loader by appending extra dex files * loaded from the application apk. This method should be called in the * attachBaseContext of your {@link Application}, see * {@link MultiDexApplication} for more explanation and an example. * * @param context application context. * @throws RuntimeException if an error occurred preventing the classloader * extension. */ public static void install(Context context) { Log.i(TAG, "install"); if (IS_VM_MULTIDEX_CAPABLE) { Log.i(TAG, "VM has multidex support, MultiDex support library is disabled."); try { clearOldDexDir(context); } catch (Throwable t) { Log.w(TAG, "Something went wrong when trying to clear old MultiDex extraction, " + "continuing without cleaning.", t); } return; } if (Build.VERSION.SDK_INT < MIN_SDK_VERSION) { throw new RuntimeException("Multi dex installation failed. SDK " + Build.VERSION.SDK_INT + " is unsupported. Min SDK version is " + MIN_SDK_VERSION + "."); } try { ApplicationInfo applicationInfo = getApplicationInfo(context); if (applicationInfo == null) { // Looks like running on a test Context, so just return without patching. return; } synchronized (installedApk) { String apkPath = applicationInfo.sourceDir; if (installedApk.contains(apkPath)) { return; } installedApk.add(apkPath); if (Build.VERSION.SDK_INT > MAX_SUPPORTED_SDK_VERSION) { Log.w(TAG, "MultiDex is not guaranteed to work in SDK version " + Build.VERSION.SDK_INT + ": SDK version higher than " + MAX_SUPPORTED_SDK_VERSION + " should be backed by " + "runtime with built-in multidex capabilty but it's not the " + "case here: java.vm.version=\"" + System.getProperty("java.vm.version") + "\""); } /* The patched class loader is expected to be a descendant of * dalvik.system.BaseDexClassLoader. We modify its * dalvik.system.DexPathList pathList field to append additional DEX * file entries. */ ClassLoader loader; try { loader = context.getClassLoader(); } catch (RuntimeException e) { /* Ignore those exceptions so that we don't break tests relying on Context like * a android.test.mock.MockContext or a android.content.ContextWrapper with a * null base Context. */ Log.w(TAG, "Failure while trying to obtain Context class loader. " + "Must be running in test mode. Skip patching.", e); return; } if (loader == null) { // Note, the context class loader is null when running Robolectric tests. Log.e(TAG, "Context class loader is null. Must be running in test mode. " + "Skip patching."); return; } File dexDir = new File(context.getFilesDir(), SECONDARY_FOLDER_NAME); List files = MultiDexExtractor.load(context, applicationInfo, dexDir, false); if (checkValidZipFiles(files)) { installSecondaryDexes(loader, dexDir, files); } else { Log.w(TAG, "Files were not valid zip files. Forcing a reload."); // Try again, but this time force a reload of the zip file. files = MultiDexExtractor.load(context, applicationInfo, dexDir, true); if (checkValidZipFiles(files)) { installSecondaryDexes(loader, dexDir, files); } else { // Second time didn't work, give up throw new RuntimeException("Zip files were not valid."); } } } } catch (Exception e) { Log.e(TAG, "Multidex installation failure", e); throw new RuntimeException("Multi dex installation failed (" + e.getMessage() + ")."); } Log.i(TAG, "install done"); } private static ApplicationInfo getApplicationInfo(Context context) throws NameNotFoundException { PackageManager pm; String packageName; try { pm = context.getPackageManager(); packageName = context.getPackageName(); } catch (RuntimeException e) { /* Ignore those exceptions so that we don't break tests relying on Context like * a android.test.mock.MockContext or a android.content.ContextWrapper with a null * base Context. */ Log.w(TAG, "Failure while trying to obtain ApplicationInfo from Context. " + "Must be running in test mode. Skip patching.", e); return null; } if (pm == null || packageName == null) { // This is most likely a mock context, so just return without patching. return null; } ApplicationInfo applicationInfo = pm.getApplicationInfo(packageName, PackageManager.GET_META_DATA); return applicationInfo; } /** * Identifies if the current VM has a native support for multidex, meaning there is no need for * additional installation by this library. * @return true if the VM handles multidex */ /* package visible for test */ static boolean isVMMultidexCapable(String versionString) { boolean isMultidexCapable = false; if (versionString != null) { Matcher matcher = Pattern.compile("(\\d+)\\.(\\d+)(\\.\\d+)?").matcher(versionString); if (matcher.matches()) { try { int major = Integer.parseInt(matcher.group(1)); int minor = Integer.parseInt(matcher.group(2)); isMultidexCapable = (major > VM_WITH_MULTIDEX_VERSION_MAJOR) || ((major == VM_WITH_MULTIDEX_VERSION_MAJOR) && (minor >= VM_WITH_MULTIDEX_VERSION_MINOR)); } catch (NumberFormatException e) { // let isMultidexCapable be false } } } Log.i(TAG, "VM with version " + versionString + (isMultidexCapable ? " has multidex support" : " does not have multidex support")); return isMultidexCapable; } private static void installSecondaryDexes(ClassLoader loader, File dexDir, List files) throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException, InvocationTargetException, NoSuchMethodException, IOException { if (!files.isEmpty()) { if (Build.VERSION.SDK_INT >= 19) { V19.install(loader, files, dexDir); } else if (Build.VERSION.SDK_INT >= 14) { V14.install(loader, files, dexDir); } else { V4.install(loader, files); } } } /** * Returns whether all files in the list are valid zip files. If {@code files} is empty, then * returns true. */ private static boolean checkValidZipFiles(List files) { for (File file : files) { if (!MultiDexExtractor.verifyZipFile(file)) { return false; } } return true; } /** * Locates a given field anywhere in the class inheritance hierarchy. * * @param instance an object to search the field into. * @param name field name * @return a field object * @throws NoSuchFieldException if the field cannot be located */ private static Field findField(Object instance, String name) throws NoSuchFieldException { for (Class clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) { try { Field field = clazz.getDeclaredField(name); if (!field.isAccessible()) { field.setAccessible(true); } return field; } catch (NoSuchFieldException e) { // ignore and search next } } throw new NoSuchFieldException("Field " + name + " not found in " + instance.getClass()); } /** * Locates a given method anywhere in the class inheritance hierarchy. * * @param instance an object to search the method into. * @param name method name * @param parameterTypes method parameter types * @return a method object * @throws NoSuchMethodException if the method cannot be located */ private static Method findMethod(Object instance, String name, Class ... parameterTypes) throws NoSuchMethodException { for (Class clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) { try { Method method = clazz.getDeclaredMethod(name, parameterTypes); if (!method.isAccessible()) { method.setAccessible(true); } return method; } catch (NoSuchMethodException e) { // ignore and search next } } throw new NoSuchMethodException("Method " + name + " with parameters " + Arrays.asList(parameterTypes) + " not found in " + instance.getClass()); } /** * Replace the value of a field containing a non null array, by a new array containing the * elements of the original array plus the elements of extraElements. * @param instance the instance whose field is to be modified. * @param fieldName the field to modify. * @param extraElements elements to append at the end of the array. */ private static void expandFieldArray(Object instance, String fieldName, Object[] extraElements) throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException { Field jlrField = findField(instance, fieldName); Object[] original = (Object[]) jlrField.get(instance); Object[] combined = (Object[]) Array.newInstance( original.getClass().getComponentType(), original.length + extraElements.length); System.arraycopy(original, 0, combined, 0, original.length); System.arraycopy(extraElements, 0, combined, original.length, extraElements.length); jlrField.set(instance, combined); } private static void clearOldDexDir(Context context) throws Exception { ApplicationInfo applicationInfo = getApplicationInfo(context); if (applicationInfo == null) { // Looks like running on a test Context, so just return. return; } synchronized (installedApk) { String apkPath = applicationInfo.sourceDir; if (installedApk.contains(apkPath)) { return; } installedApk.add(apkPath); } File dexDir = new File(context.getFilesDir(), SECONDARY_FOLDER_NAME); if (dexDir.isDirectory()) { Log.i(TAG, "Clearing old secondary dex dir (" + dexDir.getPath() + ")."); File[] files = dexDir.listFiles(); if (files == null) { Log.w(TAG, "Failed to list secondary dex dir content (" + dexDir.getPath() + ")."); return; } for (File oldFile : files) { Log.i(TAG, "Trying to delete old file " + oldFile.getPath() + " of size " + oldFile.length()); if (!oldFile.delete()) { Log.w(TAG, "Failed to delete old file " + oldFile.getPath()); } else { Log.i(TAG, "Deleted old file " + oldFile.getPath()); } } if (!dexDir.delete()) { Log.w(TAG, "Failed to delete secondary dex dir " + dexDir.getPath()); } else { Log.i(TAG, "Deleted old secondary dex dir " + dexDir.getPath()); } } } /** * Installer for platform versions 19. */ private static final class V19 { private static void install(ClassLoader loader, List additionalClassPathEntries, File optimizedDirectory) throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException, InvocationTargetException, NoSuchMethodException { /* The patched class loader is expected to be a descendant of * dalvik.system.BaseDexClassLoader. We modify its * dalvik.system.DexPathList pathList field to append additional DEX * file entries. */ Field pathListField = findField(loader, "pathList"); Object dexPathList = pathListField.get(loader); ArrayList suppressedExceptions = new ArrayList (); expandFieldArray(dexPathList, "dexElements", makeDexElements(dexPathList, new ArrayList (additionalClassPathEntries), optimizedDirectory, suppressedExceptions)); if (suppressedExceptions.size() > 0) { for (IOException e : suppressedExceptions) { Log.w(TAG, "Exception in makeDexElement", e); } Field suppressedExceptionsField = findField(loader, "dexElementsSuppressedExceptions"); IOException[] dexElementsSuppressedExceptions = (IOException[]) suppressedExceptionsField.get(loader); if (dexElementsSuppressedExceptions == null) { dexElementsSuppressedExceptions = suppressedExceptions.toArray( new IOException[suppressedExceptions.size()]); } else { IOException[] combined = new IOException[suppressedExceptions.size() + dexElementsSuppressedExceptions.length]; suppressedExceptions.toArray(combined); System.arraycopy(dexElementsSuppressedExceptions, 0, combined, suppressedExceptions.size(), dexElementsSuppressedExceptions.length); dexElementsSuppressedExceptions = combined; } suppressedExceptionsField.set(loader, dexElementsSuppressedExceptions); } } /** * A wrapper around * {@code private static final dalvik.system.DexPathList#makeDexElements}. */ private static Object[] makeDexElements( Object dexPathList, ArrayList files, File optimizedDirectory, ArrayList suppressedExceptions) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { Method makeDexElements = findMethod(dexPathList, "makeDexElements", ArrayList.class, File.class, ArrayList.class); return (Object[]) makeDexElements.invoke(dexPathList, files, optimizedDirectory, suppressedExceptions); } } /** * Installer for platform versions 14, 15, 16, 17 and 18. */ private static final class V14 { private static void install(ClassLoader loader, List additionalClassPathEntries, File optimizedDirectory) throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException, InvocationTargetException, NoSuchMethodException { /* The patched class loader is expected to be a descendant of * dalvik.system.BaseDexClassLoader. We modify its * dalvik.system.DexPathList pathList field to append additional DEX * file entries. */ Field pathListField = findField(loader, "pathList"); Object dexPathList = pathListField.get(loader); expandFieldArray(dexPathList, "dexElements", makeDexElements(dexPathList, new ArrayList (additionalClassPathEntries), optimizedDirectory)); } /** * A wrapper around * {@code private static final dalvik.system.DexPathList#makeDexElements}. */ private static Object[] makeDexElements( Object dexPathList, ArrayList files, File optimizedDirectory) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException { Method makeDexElements = findMethod(dexPathList, "makeDexElements", ArrayList.class, File.class); return (Object[]) makeDexElements.invoke(dexPathList, files, optimizedDirectory); } } /** * Installer for platform versions 4 to 13. */ private static final class V4 { private static void install(ClassLoader loader, List additionalClassPathEntries) throws IllegalArgumentException, IllegalAccessException, NoSuchFieldException, IOException { /* The patched class loader is expected to be a descendant of * dalvik.system.DexClassLoader. We modify its * fields mPaths, mFiles, mZips and mDexs to append additional DEX * file entries. */ int extraSize = additionalClassPathEntries.size(); Field pathField = findField(loader, "path"); StringBuilder path = new StringBuilder((String) pathField.get(loader)); String[] extraPaths = new String[extraSize]; File[] extraFiles = new File[extraSize]; ZipFile[] extraZips = new ZipFile[extraSize]; DexFile[] extraDexs = new DexFile[extraSize]; for (ListIterator iterator = additionalClassPathEntries.listIterator(); iterator.hasNext();) { File additionalEntry = iterator.next(); String entryPath = additionalEntry.getAbsolutePath(); path.append(':').append(entryPath); int index = iterator.previousIndex(); extraPaths[index] = entryPath; extraFiles[index] = additionalEntry; extraZips[index] = new ZipFile(additionalEntry); extraDexs[index] = DexFile.loadDex(entryPath, entryPath + ".dex", 0); } pathField.set(loader, path.toString()); expandFieldArray(loader, "mPaths", extraPaths); expandFieldArray(loader, "mFiles", extraFiles); expandFieldArray(loader, "mZips", extraZips); expandFieldArray(loader, "mDexs", extraDexs); } }}
MultiDexExtractor
负责把apk中的classesN.dex 解析到 指定的dexDir中（/data/data/packageName/files/secondary-dex/），并返回files数组
/* * Copyright (C) 2013 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package android.support.multidex;import android.content.Context;import android.content.SharedPreferences;import android.content.pm.ApplicationInfo;import android.os.Build;import android.util.Log;import java.io.BufferedOutputStream;import java.io.Closeable;import java.io.File;import java.io.FileFilter;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.lang.reflect.InvocationTargetException;import java.lang.reflect.Method;import java.util.ArrayList;import java.util.List;import java.util.zip.ZipEntry;import java.util.zip.ZipException;import java.util.zip.ZipFile;import java.util.zip.ZipOutputStream;/** * Exposes application secondary dex files as files in the application data * directory. */final class MultiDexExtractor { private static final String TAG = MultiDex.TAG; /** * We look for additional dex files named {@code classes2.dex}, * {@code classes3.dex}, etc. */ private static final String DEX_PREFIX = "classes"; private static final String DEX_SUFFIX = ".dex"; private static final String EXTRACTED_NAME_EXT = ".classes"; private static final String EXTRACTED_SUFFIX = ".zip"; private static final int MAX_EXTRACT_ATTEMPTS = 3; private static final String PREFS_FILE = "multidex.version"; private static final String KEY_TIME_STAMP = "timestamp"; private static final String KEY_CRC = "crc"; private static final String KEY_DEX_NUMBER = "dex.number"; /** * Size of reading buffers. */ private static final int BUFFER_SIZE = 0x4000; /* Keep value away from 0 because it is a too probable time stamp value */ private static final long NO_VALUE = -1L; /** * Extracts application secondary dexes into files in the application data * directory. * * @return a list of files that were created. The list may be empty if there * are no secondary dex files. * @throws IOException if encounters a problem while reading or writing * secondary dex files */ static List load(Context context, ApplicationInfo applicationInfo, File dexDir, boolean forceReload) throws IOException { Log.i(TAG, "MultiDexExtractor.load(" + applicationInfo.sourceDir + ", " + forceReload + ")"); final File sourceApk = new File(applicationInfo.sourceDir); File archive = new File(applicationInfo.sourceDir); long currentCrc = getZipCrc(archive); List files; if (!forceReload && !isModified(context, archive, currentCrc)) { try { files = loadExistingExtractions(context, sourceApk, dexDir); } catch (IOException ioe) { Log.w(TAG, "Failed to reload existing extracted secondary dex files," + " falling back to fresh extraction", ioe); files = performExtractions(sourceApk, dexDir); putStoredApkInfo(context, getTimeStamp(sourceApk), currentCrc, files.size() + 1); } } else { Log.i(TAG, "Detected that extraction must be performed."); files = performExtractions(sourceApk, dexDir); putStoredApkInfo(context, getTimeStamp(sourceApk), currentCrc, files.size() + 1); } Log.i(TAG, "load found " + files.size() + " secondary dex files"); return files; } private static List loadExistingExtractions(Context context, File sourceApk, File dexDir) throws IOException { Log.i(TAG, "loading existing secondary dex files"); final String extractedFilePrefix = sourceApk.getName() + EXTRACTED_NAME_EXT; int totalDexNumber = getMultiDexPreferences(context).getInt(KEY_DEX_NUMBER, 1); final List files = new ArrayList (totalDexNumber); for (int secondaryNumber = 2; secondaryNumber <= totalDexNumber; secondaryNumber++) { String fileName = extractedFilePrefix + secondaryNumber + EXTRACTED_SUFFIX; File extractedFile = new File(dexDir, fileName); if (extractedFile.isFile()) { files.add(extractedFile); if (!verifyZipFile(extractedFile)) { Log.i(TAG, "Invalid zip file: " + extractedFile); throw new IOException("Invalid ZIP file."); } } else { throw new IOException("Missing extracted secondary dex file '" + extractedFile.getPath() + "'"); } } return files; } private static boolean isModified(Context context, File archive, long currentCrc) { SharedPreferences prefs = getMultiDexPreferences(context); return (prefs.getLong(KEY_TIME_STAMP, NO_VALUE) != getTimeStamp(archive)) || (prefs.getLong(KEY_CRC, NO_VALUE) != currentCrc); } private static long getTimeStamp(File archive) { long timeStamp = archive.lastModified(); if (timeStamp == NO_VALUE) { // never return NO_VALUE timeStamp--; } return timeStamp; } private static long getZipCrc(File archive) throws IOException { long computedValue = ZipUtil.getZipCrc(archive); if (computedValue == NO_VALUE) { // never return NO_VALUE computedValue--; } return computedValue; } private static List performExtractions(File sourceApk, File dexDir) throws IOException { final String extractedFilePrefix = sourceApk.getName() + EXTRACTED_NAME_EXT; // Ensure that whatever deletions happen in prepareDexDir only happen if the zip that // contains a secondary dex file in there is not consistent with the latest apk. Otherwise, // multi-process race conditions can cause a crash loop where one process deletes the zip // while another had created it. prepareDexDir(dexDir, extractedFilePrefix); List files = new ArrayList (); final ZipFile apk = new ZipFile(sourceApk); try { int secondaryNumber = 2; ZipEntry dexFile = apk.getEntry(DEX_PREFIX + secondaryNumber + DEX_SUFFIX); while (dexFile != null) { String fileName = extractedFilePrefix + secondaryNumber + EXTRACTED_SUFFIX; File extractedFile = new File(dexDir, fileName); files.add(extractedFile); Log.i(TAG, "Extraction is needed for file " + extractedFile); int numAttempts = 0; boolean isExtractionSuccessful = false; while (numAttempts < MAX_EXTRACT_ATTEMPTS && !isExtractionSuccessful) { numAttempts++; // Create a zip file (extractedFile) containing only the secondary dex file // (dexFile) from the apk. extract(apk, dexFile, extractedFile, extractedFilePrefix); // Verify that the extracted file is indeed a zip file. isExtractionSuccessful = verifyZipFile(extractedFile); // Log the sha1 of the extracted zip file Log.i(TAG, "Extraction " + (isExtractionSuccessful ? "success" : "failed") + " - length " + extractedFile.getAbsolutePath() + ": " + extractedFile.length()); if (!isExtractionSuccessful) { // Delete the extracted file extractedFile.delete(); if (extractedFile.exists()) { Log.w(TAG, "Failed to delete corrupted secondary dex '" + extractedFile.getPath() + "'"); } } } if (!isExtractionSuccessful) { throw new IOException("Could not create zip file " + extractedFile.getAbsolutePath() + " for secondary dex (" + secondaryNumber + ")"); } secondaryNumber++; dexFile = apk.getEntry(DEX_PREFIX + secondaryNumber + DEX_SUFFIX); } } finally { try { apk.close(); } catch (IOException e) { Log.w(TAG, "Failed to close resource", e); } } return files; } private static void putStoredApkInfo(Context context, long timeStamp, long crc, int totalDexNumber) { SharedPreferences prefs = getMultiDexPreferences(context); SharedPreferences.Editor edit = prefs.edit(); edit.putLong(KEY_TIME_STAMP, timeStamp); edit.putLong(KEY_CRC, crc); /* SharedPreferences.Editor doc says that apply() and commit() "atomically performs the * requested modifications" it should be OK to rely on saving the dex files number (getting * old number value would go along with old crc and time stamp). */ edit.putInt(KEY_DEX_NUMBER, totalDexNumber); apply(edit); } private static SharedPreferences getMultiDexPreferences(Context context) { return context.getSharedPreferences(PREFS_FILE, Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB ? Context.MODE_PRIVATE : Context.MODE_PRIVATE | Context.MODE_MULTI_PROCESS); } /** * This removes any files that do not have the correct prefix. */ private static void prepareDexDir(File dexDir, final String extractedFilePrefix) throws IOException { dexDir.mkdir(); if (!dexDir.isDirectory()) { throw new IOException("Failed to create dex directory " + dexDir.getPath()); } // Clean possible old files FileFilter filter = new FileFilter() { @Override public boolean accept(File pathname) { return !pathname.getName().startsWith(extractedFilePrefix); } }; File[] files = dexDir.listFiles(filter); if (files == null) { Log.w(TAG, "Failed to list secondary dex dir content (" + dexDir.getPath() + ")."); return; } for (File oldFile : files) { Log.w(TAG, "Trying to delete old file " + oldFile.getPath() + " of size " + oldFile.length()); if (!oldFile.delete()) { Log.w(TAG, "Failed to delete old file " + oldFile.getPath()); } else { Log.w(TAG, "Deleted old file " + oldFile.getPath()); } } } private static void extract(ZipFile apk, ZipEntry dexFile, File extractTo, String extractedFilePrefix) throws IOException, FileNotFoundException { InputStream in = apk.getInputStream(dexFile); ZipOutputStream out = null; File tmp = File.createTempFile(extractedFilePrefix, EXTRACTED_SUFFIX, extractTo.getParentFile()); Log.i(TAG, "Extracting " + tmp.getPath()); try { out = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(tmp))); try { ZipEntry classesDex = new ZipEntry("classes.dex"); // keep zip entry time since it is the criteria used by Dalvik classesDex.setTime(dexFile.getTime()); out.putNextEntry(classesDex); byte[] buffer = new byte[BUFFER_SIZE]; int length = in.read(buffer); while (length != -1) { out.write(buffer, 0, length); length = in.read(buffer); } out.closeEntry(); } finally { out.close(); } Log.i(TAG, "Renaming to " + extractTo.getPath()); if (!tmp.renameTo(extractTo)) { throw new IOException("Failed to rename \"" + tmp.getAbsolutePath() + "\" to \"" + extractTo.getAbsolutePath() + "\""); } } finally { closeQuietly(in); tmp.delete(); // return status ignored } } /** * Returns whether the file is a valid zip file. */ static boolean verifyZipFile(File file) { try { ZipFile zipFile = new ZipFile(file); try { zipFile.close(); return true; } catch (IOException e) { Log.w(TAG, "Failed to close zip file: " + file.getAbsolutePath()); } } catch (ZipException ex) { Log.w(TAG, "File " + file.getAbsolutePath() + " is not a valid zip file.", ex); } catch (IOException ex) { Log.w(TAG, "Got an IOException trying to open zip file: " + file.getAbsolutePath(), ex); } return false; } /** * Closes the given {@code Closeable}. Suppresses any IO exceptions. */ private static void closeQuietly(Closeable closeable) { try { closeable.close(); } catch (IOException e) { Log.w(TAG, "Failed to close resource", e); } } // The following is taken from SharedPreferencesCompat to avoid having a dependency of the // multidex support library on another support library. private static Method sApplyMethod; // final static { try { Class cls = SharedPreferences.Editor.class; sApplyMethod = cls.getMethod("apply"); } catch (NoSuchMethodException unused) { sApplyMethod = null; } } private static void apply(SharedPreferences.Editor editor) { if (sApplyMethod != null) { try { sApplyMethod.invoke(editor); return; } catch (InvocationTargetException unused) { // fall through } catch (IllegalAccessException unused) { // fall through } } editor.commit(); }}