將ip轉爲整數以及整數轉爲ip的java實現

一個ip地址用字符串保存,長度爲(7-15)也就是(14-30bytes),而用int保存只需要4bytes,所以下面的代碼:

	/**
	 * ip字符串轉整數
	 * ip是.分割的整數字符串,按照r進制轉十進制的規律,按權相加求和,這裏的權是256.
	 * @param ip
	 * @return
	 */
		public int ip2Int(String ip){
		if(null == ip || "".equals(ip.trim()) || !checkIP(ip)) return 0;
		String[] ipStrs = ip.split("\\.");//分割ip
		int result = 0;
		for(int i = 0;i < 4;i ++){
			Integer ipSubInteger = Integer.parseInt(ipStrs[i]);
			if(ipSubInteger > 255) {//正則驗證不能爲負數
				result = 0;
				break;
			}
			result += (ipSubInteger << (24 - i * 8));
		}
		return result;
	}
	
	/*正則驗證ip*/
	private boolean checkIP(String ip){
		return ip.matches("\\d{1,3}(\\.\\d{1,3}){3}");
	}
	
	/**
	 * 整數轉ip
	 * @param ip
	 * @return
	 */
	public String int2Ip(int ip){
		StringBuilder builder = new StringBuilder(String.valueOf(ip >>> 24));
		builder.append(".");
		builder.append(String.valueOf((ip & 0X00FFFFFF) >>> 16));
		builder.append(".");
		builder.append(String.valueOf((ip & 0X0000FFFF) >>> 8));
		builder.append(".");
		builder.append(String.valueOf(ip & 0X000000FF));
		return builder.toString();
	}