JAVA几个很有用的工具函数

/**
	 * Logs the message.
	 * 
	 * @param msg
	 *            the message.
	 */
	private void logMsg(String msg) {

		DateFormat dateFormat = new SimpleDateFormat("[dd-MM-yyyy HH:mm:ss]: ");
		Date date = new Date();
		String oldMsg = mResponseTextView.getText().toString();

		mResponseTextView
				.setText(oldMsg + "\n" + dateFormat.format(date) + msg);

		if (mResponseTextView.getLineCount() > MAX_LINES) {
			mResponseTextView.scrollTo(0,
					(mResponseTextView.getLineCount() - MAX_LINES)
							* mResponseTextView.getLineHeight());
		}
	}

	/**
	 * Logs the contents of buffer.
	 * 
	 * @param buffer
	 *            the buffer.
	 * @param bufferLength
	 *            the buffer length.
	 */
	private void logBuffer(byte[] buffer, int bufferLength) {

		String bufferString = "";

		for (int i = 0; i < bufferLength; i++) {

			String hexChar = Integer.toHexString(buffer[i] & 0xFF);
			if (hexChar.length() == 1) {
				hexChar = "0" + hexChar;
			}

			if (i % 16 == 0) {

				if (bufferString != "") {

					logMsg(bufferString);
					bufferString = "";
				}
			}

			bufferString += hexChar.toUpperCase() + " ";
		}

		if (bufferString != "") {
			logMsg(bufferString);
		}
	}

	/**
	 * Converts the HEX string to byte array.
	 * 
	 * @param hexString
	 *            the HEX string.
	 * @return the byte array.
	 */
	private byte[] toByteArray(String hexString) {

		int hexStringLength = hexString.length();
		byte[] byteArray = null;
		int count = 0;
		char c;
		int i;

		// Count number of hex characters
		for (i = 0; i < hexStringLength; i++) {

			c = hexString.charAt(i);
			if (c >= '0' && c <= '9' || c >= 'A' && c <= 'F' || c >= 'a'
					&& c <= 'f') {
				count++;
			}
		}

		byteArray = new byte[(count + 1) / 2];
		boolean first = true;
		int len = 0;
		int value;
		for (i = 0; i < hexStringLength; i++) {

			c = hexString.charAt(i);
			if (c >= '0' && c <= '9') {
				value = c - '0';
			} else if (c >= 'A' && c <= 'F') {
				value = c - 'A' + 10;
			} else if (c >= 'a' && c <= 'f') {
				value = c - 'a' + 10;
			} else {
				value = -1;
			}

			if (value >= 0) {

				if (first) {

					byteArray[len] = (byte) (value << 4);

				} else {

					byteArray[len] |= value;
					len++;
				}

				first = !first;
			}
		}

		return byteArray;
	}

	/**
	 * Converts the integer to HEX string.
	 * 
	 * @param i
	 *            the integer.
	 * @return the HEX string.
	 */
	private String toHexString(int i) {

		String hexString = Integer.toHexString(i);
		if (hexString.length() % 2 != 0) {
			hexString = "0" + hexString;
		}

		return hexString.toUpperCase();
	}

	/**
	 * Converts the byte array to HEX string.
	 * 
	 * @param buffer
	 *            the buffer.
	 * @return the HEX string.
	 */
	private String toHexString(byte[] buffer) {

		String bufferString = "";

		for (int i = 0; i < buffer.length; i++) {

			String hexChar = Integer.toHexString(buffer[i] & 0xFF);
			if (hexChar.length() == 1) {
				hexChar = "0" + hexChar;
			}

			bufferString += hexChar.toUpperCase() + " ";
		}

		return bufferString;
	}