txt多格式读取

        InputStream inputStream = new FileInputStream(file);
		byte[] head = new byte[3];
		inputStream.read(head);
		String code = "gb2312";
		if (head[0] == -1 && head[1] == -2)
			code = "UTF-16";
		if (head[0] == -2 && head[1] == -1)
			code = "Unicode";
		if (head[0] == -17 && head[1] == -69 && head[2] == -65)
			code = "UTF-8";
		InputStreamReader isr = new InputStreamReader(inputStream, code);
		BufferedReader buffer = new BufferedReader(isr);