java—实用小技巧——解析命令行参数

    我们在进行项目中的调试的时候，特别是对于Server的调试，写出来的Client总是不方便改一些参数，要么就是修改到配置文件里，要么就是重新打包，不甚麻烦，这时候一个可以在命令行指定参数的功能就可以很好的解决了，

直接上代码：

public class Config {

	@SuppressWarnings("unused")
	private final static Logger LOGGER = Logger.getLogger(Config.class);
	private static final Options OPTIONS = new Options();

	private static final String OPTION_HELP = "h";

	private static final String OPTION_SERVER_ADDRESS = "sa";
	private static final String OPTION_SERVER_PORT = "sp";
	private static final String OPTION_LOCAL_PORT = "lp";
	private static final String OPTION_ENDPOINT = "ep";
	private static final String OPTION_PAYLOAD = "d";

	static String serverAddress;
	static int serverPort;
	static int localPort;
	static String endpoint;
	static String payload;

	static {
		OPTIONS.addOption(OptionBuilder.withDescription("Print Help").withLongOpt("help").create(OPTION_HELP));
		OPTIONS.addOption(OptionBuilder.withDescription("server address").hasArg().withArgName("server_address")
				.create(OPTION_SERVER_ADDRESS));
		OPTIONS.addOption(OptionBuilder.withDescription("server port").hasArg().withArgName("server_port")
				.create(OPTION_SERVER_PORT));
		OPTIONS.addOption(OptionBuilder.withDescription("local port").hasArg().withArgName("local_port")
				.create(OPTION_LOCAL_PORT));
		OPTIONS.addOption(OptionBuilder.withDescription("endpoint name").hasArg().withArgName("endpoint")
				.create(OPTION_ENDPOINT));
		OPTIONS.addOption(
				OptionBuilder.withDescription("payload in hex").hasArg().withArgName("payload").create(OPTION_PAYLOAD));

	}

	public static void printUsage(String message) {
		if (message != null) {
			System.out.println(message);
		}

		HelpFormatter formatter = new HelpFormatter();

		String header = "\nEmulate Coap Client(s)";
		String footer = "\n\nexample: java -cp coap-client.jar com.client.sim.SimClient -sa 23.212.7.182 -sp 5685 "
				+ "-lp 11162 -ep 863783037777777 -d 00001111 \n";

		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		PrintWriter writer = new PrintWriter(baos);
		formatter.printHelp(writer, 200, "java -jar coap-client.jar ", header, OPTIONS, 4, 4, footer, true);
		writer.close();

		System.out.println(baos.toString());
	}

	/**
	 *
	 * @param parser
	 * @param args
	 * @return <code>true</code> if command line successfully parsed,
	 *         <code>false</code> if a problem occurred or help param was
	 *         specified
	 */
	static boolean parseArguments(CommandLineParser parser, String[] args) {
		try {
			CommandLine cmd;
			cmd = parser.parse(OPTIONS, args);

			if (cmd.hasOption(OPTION_HELP)) {
				printUsage(null);
				return false;
			}
			if (cmd.hasOption(OPTION_SERVER_ADDRESS)) {
				serverAddress = cmd.getOptionValue(OPTION_SERVER_ADDRESS);
			}
			if (cmd.hasOption(OPTION_SERVER_PORT)) {
				serverPort = Integer.parseInt(cmd.getOptionValue(OPTION_SERVER_PORT));
			}
			if (cmd.hasOption(OPTION_LOCAL_PORT)) {
				localPort = Integer.parseInt(cmd.getOptionValue(OPTION_LOCAL_PORT));
			}
			if (cmd.hasOption(OPTION_ENDPOINT)) {
				endpoint = cmd.getOptionValue(OPTION_ENDPOINT);
			}
			if (cmd.hasOption(OPTION_PAYLOAD)) {
				payload = cmd.getOptionValue(OPTION_PAYLOAD);
			}
		} catch (Exception ex) {
			printUsage(ex.getClass().getSimpleName() + ": " + ex.getMessage());
			return false;
		}
		return true;
	}

	public static int getServerPort() {
		return serverPort;
	}

	public static void setServerPort(int serverPort) {
		Config.serverPort = serverPort;
	}

	public static int getLocalPort() {
		return localPort;
	}

	public static void setLocalPort(int localPort) {
		Config.localPort = localPort;
	}

	public static String getEndpoint() {
		return endpoint;
	}

	public static void setEndpoint(String endpoint) {
		Config.endpoint = endpoint;
	}

	public static String getPayload() {
		return payload;
	}

	public static void setPayload(String payload) {
		Config.payload = payload;
	}

	public static String getServerAddress() {
		return serverAddress;
	}

	public static void setServerAddress(String serverAddress) {
		Config.serverAddress = serverAddress;
	}

}

调用：

private static DatagramSocket datagramSocket;
	private static DatagramPacket datagramPacket;

	public static void main(String[] args) {

		CommandLineParser parser = new PosixParser();

		if (!Config.parseArguments(parser, args)) {
			return;
		}

		try {

			/*** 发送数据 ***/
			// 初始化datagramSocket,注意与前面Server端实现的差别
			datagramSocket = new DatagramSocket(new InetSocketAddress(Config.getLocalPort()));
			// 使用DatagramPacket(byte buf[], int length, InetAddress address, int port)函数组装发送UDP数据报
			byte[] buf = Config.getPayload().getBytes();
			InetAddress address = InetAddress.getByName(Config.getServerAddress());
			datagramPacket = new DatagramPacket(buf, buf.length, address, Config.getServerPort());
			// 发送数据
			datagramSocket.send(datagramPacket);

			/*** 接收数据 ***/
			byte[] receBuf = new byte[1024];
			DatagramPacket recePacket = new DatagramPacket(receBuf, receBuf.length);
			datagramSocket.receive(recePacket);

			String receStr = new String(recePacket.getData(), 0, recePacket.getLength());
			System.out.println("Client Rece Ack: " + receStr + " -- "
					+ Hex.encodeHexString(recePacket.getData()).substring(0, receStr.length() * 2));
			System.out.println(recePacket.getPort());

		} catch (SocketException e) {
			e.printStackTrace();
		} catch (UnknownHostException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			// 关闭socket
			if (datagramSocket != null) {
				datagramSocket.close();
			}
		}
	}

命令行执行jar包：

java -cp coap-client-test-1.0-SNAPSHOT.jar com.client.sim.SimUdpClient -sa 127.0.0.1 -sp 10000 -lp 10006 -d ff
e8e91bf6b308130300011701590026006afe0000006037fc55ff026f6388010b01cd

这样就可以直接在命令行修改参数，愉快的测试啦！！！