import andROId.content.Context; import android.os.environment; import android.os.Handler; import android.os.Looper; import android.os.Message;  import java.io.File; import java.io.FileOutputStream; import java.io.InputStream;  /**  * Created by shenhua on 1/17/2017.  * Email shenhuanet@126.COM  */ public class FileUtils {   PRivate static FileUtils instance;  private static final int SUCCESS = 1;  private static final int FAILED = 0;  private Context context;  private FileoperateCallback callback;  private volatile boolean isSuccess;  private String errorStr;   public static FileUtils getInstance(Context context) {   if (instance == null)    instance = new FileUtils(context);   return instance;  }   private FileUtils(Context context) {   this.context = context;  }   private Handler handler = new Handler(Looper.getMainLooper()) {   @override   public void handleMessage(Message msg) {    super.handleMessage(msg);    if (callback != null) {     if (msg.what == SUCCESS) {      callback.onSuccess();     }     if (msg.what == FAILED) {      callback.onFailed(msg.obj.toString());     }    }   }  };   public FileUtils copyAssetsToSD(final String srcPath, final String sdPath) {   new Thread(new Runnable() {    @Override    public void run() {     copyAssetsToDst(context, srcPath, sdPath);     if (isSuccess)      handler.oBTainMessage(SUCCESS).sendToTarget();     else      handler.obtainMessage(FAILED, errorStr).sendToTarget();    }   }).start();   return this;  }   public void setFileOperateCallback(FileOperateCallback callback) {   this.callback = callback;  }   private void copyAssetsToDst(Context context, String srcPath, String dstPath) {   try {    String filenames[] = context.getAssets().list(srcPath);    if (fileNames.length > 0) {     File file = new File(Environment.getExternalStorageDirectory(), dstPath);     if (!file.exists()) file.mkdirs();     for (String fileName : fileNames) {      if (!srcPath.equals("")) { // assets 文件夹下的目录       copyAssetsToDst(context, srcPath + File.separator + fileName, dstPath + File.separator + fileName);      } else { // assets 文件夹       copyAssetsToDst(context, fileName, dstPath + File.separator + fileName);      }     }    } else {     File outFile = new File(Environment.getExternalStorageDirectory(), dstPath);     InputStream is = context.getAssets().open(srcPath);     FileOutputStream fos = new FileOutputStream(outFile);     byte[] buffer = new byte[1024];     int byteCount;     while ((byteCount = is.read(buffer)) != -1) {      fos.write(buffer, 0, byteCount);     }     fos.flush();     is.close();     fos.close();    }    isSuccess = true;   } catch (Exception e) {    e.printStackTrace();    errorStr = e.getMessage();    isSuccess = false;   }  }   public interface FileOperateCallback {   void onSuccess();    void onFailed(String error);  }  }

 FileUtils.getInstance(Context context).copyAssetsToSD("apks","app/apks");

 FileUtils.getInstance(Context context).copyAssetsToSD("apks","app/apks").setFileOperateCallback(new FileUtils.FileOperateCallback() {  @Override   public void onSuccess() {   // TODO: 文件复制成功时，主线程回调    }     @Override    public void onFailed(String error) {     // TODO: 文件复制失败时，主线程回调    }   });