由於工作的需要看了下Eclipse下android65535的解決方案，查了好多文件，真心的發自內心的說一句請不要再拷貝別人的部落格了，害人，真害人。
　　接下來我說下我的實現方式，首先說下65535的最可能的觸發原因(三方jar用的太多了)
　　首先：利用ant 軟體合併jar包：
　　ant 安裝步驟：
　　
　　
　　把剛剛配置好的%ANT_HOME%\bin;放在path後面，注意分號，全部點選確認
　　
　　按win+r 輸入cmd 或者在電腦桌面按shift+滑鼠右鍵，點選在此處開啟命令視窗 輸入 ant
ant 配置成功

合併jar包：
把專案的全部jar包複製進同一個資料夾內，並新建index.xml

<?xml version="1.0" encoding="utf-8"?>
<project basedir="C:\Users\Desktop\jar" default="makeSuperJar" name="base">

    <target description="description" name="makeSuperJar">

        <jar destfile="base.jar">
        <zipfileset src="asmack.jar"/>
        <zipfileset
 
 src="BaiduLBS_Android.jar"/>
        <zipfileset src="bugly_crash_release.jar"/>
        <zipfileset src="core-3.0.0.jar"/>
        <zipfileset src="Downloader-1.3.7.jar"/>
        <zipfileset src="httpmime-4.1.3.jar"/>
        <zipfileset src="j2v8-4.8.0.jar"/>
        <zipfileset
 
 src="Msc.jar"/>
        <zipfileset src="nineoldandroids-2.4.0.jar"/>
        <zipfileset src="org.apache.http.legacy.jar"/>
        <zipfileset src="ScriptAPI_js.jar"/>
        <zipfileset src="SocialSDK_AtFriends.jar"/>
        <zipfileset src="SocialSDK_QQZone_1.jar"/>
        <zipfileset src="SocialSDK_QQZone_2.jar"/>
        <zipfileset src="SocialSDK_QQZone_3.jar"/>
        <zipfileset src="SocialSDK_Sina.jar"/>
        <zipfileset src="SocialSDK_WeiXin_1.jar"/>
        <zipfileset src="SocialSDK_WeiXin_2.jar"/>
        <zipfileset src="systembartint-1.0.4.jar"/>
        <zipfileset src="umeng_social_sdk.jar"/>
        <zipfileset src="universal-image-loader-1.9.2.jar"/>
        <zipfileset src="UPPayAssistEx.jar"/>
        <zipfileset src="UPPayPluginEx.jar"/>
        <zipfileset src="wheel-widget.jar"/>
        </jar>
    </target>

</project>

　這裡你只需要改下你的basedir目錄地址,destfile輸出檔案的名字和zipfileset你需要合併的jar即可。
　
開啟cmd 輸入 ant -buildfile C:\Users\Desktop\jar\index.xml 回車

然後將合併的jar轉換成dex檔案，怎麼找到dx工具，見圖

直接在當前路徑下執行cmd命令，然後輸入
dx - -dex - -output=E:\libs\classes2.dex E:\libs\all.jar，
這裡我寫的是我自己的路徑。輸出檔案為classes2.dex,由於apk預設會將專案中的class檔案編譯成classes.dex，所以這裡你需要更改下你的輸出檔名，這裡這個名字要有規範，嚴格的命名classes2.dex,classes3.dex…..,至於為什麼，這是MultiDex的自己要求的，這裡是仿Android sutudio的分包方式，請嚴格執行。
之後將classes.dex檔案放置到專案的src目錄下即可。

　　現在執行你還差最後一步匯入MutiDex類庫，你可以在網上去下載，或者直接copy我下邊的程式碼，這裡最主要想說的是如何使用

　　在你的專案的Application類中配置如下程式碼：
　　

@Override
       protected void attachBaseContext(Context base) {
           // TODO Auto-generated method stub
           super.attachBaseContext(base);
           MultiDex.install(this);

       }

到這裡基本上配置算是完成了，this all over.

以下是類庫MultiDex的類庫Code，有需要的直接拷貝即可，這裡不作為關鍵點來分析

　　MultiDex類：
　　

/*
 * 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)}.
 *
 * <p/>
 * 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 OLD_SECONDARY_FOLDER_NAME = "secondary-dexes";

    private static final String SECONDARY_FOLDER_NAME = "code_cache" + File.separator +
        "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<String> installedApk = new HashSet<String>();

    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.");
            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;
                }

                try {
                  clearOldDexDir(context);
                } catch (Throwable t) {
                  Log.w(TAG, "Something went wrong when trying to clear old MultiDex extraction, "
                      + "continuing without cleaning.", t);
                }

                File dexDir = new File(applicationInfo.dataDir, SECONDARY_FOLDER_NAME);
                List<File> 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<File> 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<File> 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 {
        File dexDir = new File(context.getFilesDir(), OLD_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<File> 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<IOException> suppressedExceptions = new ArrayList<IOException>();
            expandFieldArray(dexPathList, "dexElements", makeDexElements(dexPathList,
                    new ArrayList<File>(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<File> files, File optimizedDirectory,
                ArrayList<IOException> 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<File> 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<File>(additionalClassPathEntries), optimizedDirectory));
        }

        /**
         * A wrapper around
         * {@code private static final dalvik.system.DexPathList#makeDexElements}.
         */
        private static Object[] makeDexElements(
                Object dexPathList, ArrayList<File> 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<File> 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<File> 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);
        }
    }

}

MultiDexApplication類

/*
 * Copyright (C) 2014 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;

/**
 * Minimal MultiDex capable application. To use the legacy multidex library there is 3 possibility:
 * <ul>
 * <li>Declare this class as the application in your AndroidManifest.xml.</li>
 * <li>Have your {@link Application} extends this class.</li>
 * <li>Have your {@link Application} override attachBaseContext starting with<br>
 * <code>
  protected void attachBaseContext(Context base) {<br>
    super.attachBaseContext(base);<br>
    MultiDex.install(this);
    </code></li>
 *   <ul>
 */
public class MultiDexApplication extends Application {
  @Override
  protected void attachBaseContext(Context base) {
    super.attachBaseContext(base);
    MultiDex.install(this);
  }
}

MultiDexExtractor類

/*
 * 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<File> 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);

        long currentCrc = getZipCrc(sourceApk);

        List<File> files;
        if (!forceReload && !isModified(context, sourceApk, 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<File> 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<File> files = new ArrayList<File>(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<File> 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<File> files = new ArrayList<File>();

        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 getMultiDexPrefe