向SD卡建立文件夾

@Override
 public void run() {
  try {
   // 檢測設備有無SD卡
   if (android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED)) {
    apkFile = Environment.getExternalStorageDirectory() + Constants.SAVEPATH + Constants.PROJECTNAME + SharedPreferenceSetting.getApkVersionCode(this) + ".apk";
   } else {
    myHandler.sendEmptyMessage(3);
    return;
   }
   URL url = new URL(SharedPreferenceSetting.getAPKURL(this));
   HttpURLConnection conn = (HttpURLConnection) url.openConnection();
   conn.connect();
   int length = conn.getContentLength();
   InputStream is = conn.getInputStream();

   File file = new File(Environment.getExternalStorageDirectory() + Constants.SAVEPATH);
   if (!file.exists()) {
    file.mkdir();
   }
   File ApkFile = new File(apkFile);
   FileOutputStream fos = new FileOutputStream(ApkFile);
   int count = 0;
   byte buf[] = new byte[1024];
   do {
    int numread = is.read(buf);
    count += numread;
    downloadProgressValue = (int) (((float) count / length) * 100);
    // 更新進度
    myHandler.sendEmptyMessage(1);
    if (numread <= 0) {
     // 下載完成通知安裝
     myHandler.sendEmptyMessage(2);
     break;
    }
    fos.write(buf, 0, numread);
   } while (!interceptFlag);// 點擊取消就中止下載.

   fos.close();
   is.close();
  } catch (MalformedURLException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }

 }