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 [email protected] */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 文件夾下的目錄      copyAssetsToDst(context, srcPath + File.separator + fileName, dstPath + File.separator + fileName);     } else { // assets 文件夾      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: 文件復(fù)制成功時(shí)，主線程回調(diào)   }   @Override   public void onFailed(String error) {    // TODO: 文件復(fù)制失敗時(shí)，主線程回調(diào)   }  });