mkdir() 只能创建一层目录.
mkdirs(),才能创建多层目录
private final String APP_FOLDER = "/sdcard/DownDemo/"; // sd卡应用目录 File folder = null; folder = new File(Environment.getExternalStorageDirectory()+ File.separator + APP_FOLDER ); if (!folder.exists()) { folder.mkdirs(); } private final String APP_FOLDER = "DownDemo"; // sd卡应用目录 folder = new File(Environment.getExternalStorageDirectory()+ File.separator + APP_FOLDER ); if (!folder.exists()) { folder.mkdir(); }