关于Google Play商店中obb文件意外情况下无法下载的处理

public synchronized void checkAccess(LicenseCheckerCallback callback) {
    // If we have a valid recent LICENSED response, we can skip asking
    // Market.
    if (mPolicy.allowAccess()) {
        Log.i(TAG, "Using cached license response");
        callback.allow(Policy.LICENSED);
    } else {
        LicenseValidator validator = new LicenseValidator(mPolicy, new NullDeviceLimiter(),
                callback, generateNonce(), mPackageName, mVersionCode);

        if (mService == null) {
            Log.i(TAG, "Binding to licensing service.");
            try {
                //------------------modify begin-----------------------
                //delete
                //这段在代码在Android5.0上会抛出IllegalArgumentException
//                    boolean bindResult = mContext
//                            .bindService(
//                                    new Intent(
//                                            new String(
//                                                    Base64.decode("Y29tLmFuZHJvaWQudmVuZGluZy5saWNlbnNpbmcuSUxpY2Vuc2luZ1NlcnZpY2U="))),
//                                    this, // ServiceConnection.
//                                    Context.BIND_AUTO_CREATE);
                
                //add
                Intent serviceIntent = new Intent(new String(Base64.decode("Y29tLmFuZHJvaWQudmVuZGluZy5saWNlbnNpbmcuSUxpY2Vuc2luZ1NlcnZpY2U=")));
                serviceIntent.setPackage("com.android.vending");

                boolean bindResult = mContext
                        .bindService(
                                serviceIntent,
                                this, // ServiceConnection.
                                Context.BIND_AUTO_CREATE);
                //------------------modify begin-----------------------

                if (bindResult) {
                    mPendingChecks.offer(validator);
                } else {
                    Log.e(TAG, "Could not bind to service.");
                    handleServiceConnectionError(validator);
                }
            } catch (SecurityException e) {
                callback.applicationError(LicenseCheckerCallback.ERROR_MISSING_PERMISSION);
            } catch (Base64DecoderException e) {
                e.printStackTrace();
            }
        } else {
            mPendingChecks.offer(validator);
            runChecks();
        }
    }
}

@Override
public void connect(Context c) {
    mContext = c;
    Intent bindIntent = new Intent(c, mDownloaderServiceClass);
    bindIntent.putExtra(PARAM_MESSENGER, mMessenger);
    /**
     * modify
     * Context.BIND_DEBUG_UNBIND
     * Context.BIND_AUTO_CREATE
     * 这里会导致绑定的服务在某些情况下无法启动，服务不启动，IDownloaderClient接口的onServiceConnected()方法就不会执行，mRemoteService为null，从而导致NullPointerException。
     * 虽然在使用mRemoteService前增加对其是否为null的判断可以避免crash，但是下载过程仍然无法监控，无法得到下载的结果。需要将这段代码替换成如下代码。也就是将BIND_DEBUG_UNBIND替换成BIND_AUTO_CREATE。
     */
    if ( !c.bindService(bindIntent, mConnection, Context.BIND_AUTO_CREATE) ) {
        if ( Constants.LOGVV ) {
            Log.d(Constants.TAG, "Service Unbound");
        }
    } else {
        mBound = true;
    }

}

protected void onCreate(Bundle savedInstanceState){
	Log.w("uuuuuuuuuu","onCreate");

    // FATE_OBB_PATH是存储obb路径的变量，getVirtualObbFileFullpath()在obb文件读取的文章中讲过
	FATE_OBB_PATH = getVirtualObbFileFullpath();//这句需要放在super.onCreate上面

	super.onCreate(savedInstanceState);

    //------------add-------------
    //如果obb文件不存在，未能在Google Play中正确下载或是用户删除，则跳转至SampleDownloaderActivity开始下载
    File file = new File(FATE_OBB_PATH);
    if (!file.exists()){
        Intent intent = new Intent(this, SampleDownloaderActivity.class);
        this.startActivity(intent);
        this.finish();
    }
    //------------add-------------
}

//修改为自己需要的参数
private static final XAPKFile[] xAPKS = {
        new XAPKFile(
                true, //isMain:是否为主要分包
                6, //fileVersion:其实就是versionCode
                182118395L //fileSize:分包文件字节大小，不知道怎么看的可以在cmd中使用dir命令查看
                )
        // main file only
};

this.runOnUiThread(new Runnable() {
    @Override
    public void run() {
        validationTask.execute(new Object());
    }
});

/**
 * Connect the stub to our service on resume.
 */
@Override
protected void onResume() {
    if (null != mDownloaderClientStub) {
        mDownloaderClientStub.connect(this);
    }
    super.onResume();
}

private void startMovie() {
    // launch the movie player activity
//        Uri mediaUri = Uri.withAppendedPath(SampleZipFileProvider.ASSET_URI,
//                "big_buck_bunny_720p_surround.m4v");
//        Intent intent = new Intent();
//        intent.setData(mediaUri);
//        intent.putExtra(Intent.EXTRA_TITLE, mediaUri.getLastPathSegment());
//        intent.setClass(this, SampleVideoPlayerActivity.class);
//        startActivity(intent);

    Intent intent = new Intent(this, MainActivity.class);
    startActivity(intent);
    finish();
}

//替换为自己的KEY，在Google后台查询自己的RSA公共密钥
private static final String BASE64_PUBLIC_KEY = "REPLACE THIS WITH YOUR PUBLIC KEY"

// must match what is declared in the Zip content provider in
// the AndroidManifest.xml file
// 这里填写你在AndroidManifest.xml文件中注册此Provider时，填写的android:authorities
private static final String AUTHORITY = "com.xxx.xxx.xxx";