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package com.github.javaclub.mq.common.util;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.util.Enumeration;
import java.util.Random;

public class Utils {
	
	public static String localIp = null;

	public static String getLocalIp() throws SocketException {
		if (localIp != null) {
			return localIp;
		}
		Enumeration netInterfaces = NetworkInterface.getNetworkInterfaces();
		InetAddress ip = null;
		while (netInterfaces.hasMoreElements()) {
			NetworkInterface ni = netInterfaces.nextElement();
			Enumeration address = ni.getInetAddresses();
			while (address.hasMoreElements()) {
				ip = address.nextElement();
				if (!ip.isSiteLocalAddress() && !ip.isLoopbackAddress() && ip.getHostAddress().indexOf(":") == -1) {// 外网IP
					// netip = ip.getHostAddress();
					break;
				} else if (ip.isSiteLocalAddress() && !ip.isLoopbackAddress() && ip.getHostAddress().indexOf(":") == -1) {// 内网IP
					localIp = ip.getHostAddress();
					return localIp;
				}
			}
		}
		return null;
	}

	public static long ipToLong(String ipAddress) {
		long result = 0;
		String[] atoms = ipAddress.split("\\.");

		for (int i = 3; i >= 0; i--) {
			result |= (Long.parseLong(atoms[3 - i]) << (i * 8));
		}

		return result & 0xFFFFFFFF;
	}

	public static String longToIp(long ip) {
		StringBuilder sb = new StringBuilder(15);

		for (int i = 0; i < 4; i++) {
			sb.insert(0, Long.toString(ip & 0xff));

			if (i < 3) {
				sb.insert(0, '.');
			}

			ip >>= 8;
		}

		return sb.toString();
	}

	public static String getRandomString(int length) {
		StringBuffer buffer = new StringBuffer("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
		StringBuffer sb = new StringBuffer();
		Random r = new Random();
		int range = buffer.length();
		for (int i = 0; i < length; i++) {
			sb.append(buffer.charAt(r.nextInt(range)));
		}
		return sb.toString();
	}
}