创建文件夹和文件

String commonPath = Environment.getExternalStorageDirectory()
				+ "/raz_english/";
		try {
			File destDir = new File(commonPath);
			if (!destDir.exists()) {
				destDir.mkdirs();
			}
			new File(destDir, ".nomedia").createNewFile();
		} catch (IOException e) {
			e.printStackTrace();
		}

需在AndroidManifest中加上：
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>