// SD卡是否存在private boolean checkSDCardStatus() { boolean SDCardStatus = false; String sDStateString = android.os.Environment.getExternalStorageState(); if (sDStateString.equals(android.os.Environment.MEDIA_MOUNTED)) {  SDCardStatus = true; } else {  // SD卡不可用 } return SDCardStatus;}// SD卡上是否有APK文件private boolean checkFileExist(String iFilePath) { boolean fileExist = false; if (checkSDCardStatus()) {  File myFile = new File(iFilePath);  if (myFile.exists()) {  fileExist = true;  } } return fileExist;}//刪除文件private void deleteApk(String iFilePath) { if (checkSDCardStatus()) {  File myFile = new File(iFilePath);  if (myFile.exists()) {  myFile.delete();  } }}//在SD卡上用txt記錄public static void logOnFile(String format, Object... args){ String logstr = String.format(format, args); SimpleDateFormat sDateFormat = new SimpleDateFormat("yyyy-MM-dd  HH:mm:ss"); String date  =  sDateFormat.format(new java.util.Date()); logstr = "/r/n-------------------------/r/n" + date + "/r/n" + logstr; FileOutputStream fout; DataOutputStream dataout; try {  fout = new FileOutputStream("http://sdcard//log.txt",true);  dataout = new DataOutputStream(fout);  dataout.writeUTF(logstr);  dataout.flush();  dataout.close();  fout.flush();  fout.close(); } catch (FileNotFoundException e) {  e.printStackTrace(); } catch (IOException e) {  e.printStackTrace(); }}