Check If A String Is Valid, Inner, Public Ip Java Example

This example include java code that can be used to check whether a given ip string is valid, inner or public ip or not. Please see code comments for detail explanation.

1.Check If A String Is Valid IP

	/* This method check whether addStr is a valid ip address or not.
	 * addStr : A given ip string.
	 * return : true means valid, false means invalid.
	 * */
	public static boolean isValidIp(String addStr)
	{
		boolean ret = true;
		// If addStr is empty or reserved address then return false.
		if("".equals(addStr) || addStr==null || "0.0.0.0".equals(addStr))
		{
			return false;
		}
		
		// Split ip address string into 4 length string array.
		String ipEle[] = addStr.split("\\.");
		// If ip address do not include four parts return false.
		if(ipEle.length!=4)
		{
			return false;
		}else
		{
			// Loop for the four parts in ip address.
			for(int i=0;i<4;i++)
			{
				String ipEleStr = ipEle[i];
				// If not integer return false.
				if(!StringTool.isInteger(ipEleStr))
				{
					return false;
				}else
				{
					// If less than zero or bigger than 256 return false.
					if(Integer.parseInt(ipEleStr)<0 || Integer.parseInt(ipEleStr)>=256)
					{
						return false;
					}else
					{
						// If the first part in ip address is 127 return false.
						if(i==0 && Integer.parseInt(ipEleStr)==127)
						{
							return false;
						}
					}					
				}
			}
		}
		
		return ret;
	}

2. Check If A String Is Inner IP

	/* This method is used to check whether ipAddress is inner ip or not. 
	 * */
	public static boolean isInnerIP(String ipAddress)
	{    
            boolean isInnerIp = false;    
        
            // Get number value for the ip string.
    	    long ipNum = getIpNum(ipAddress);    
	
    	    // Get number value for inner ip range string.
	    long aBegin = getIpNum("10.0.0.0");    
	    long aEnd = getIpNum("10.255.255.255");    
	    long bBegin = getIpNum("172.16.0.0");    
	    long bEnd = getIpNum("172.31.255.255");    
	    long cBegin = getIpNum("192.168.0.0");    
	    long cEnd = getIpNum("192.168.255.255");
	    long dBegin = getIpNum("224.0.0.0");    
	    long dEnd = getIpNum("239.255.255.255");  
	    
	    // If ipAddress exist in one of inner ip range then it is an inner ip.
	    isInnerIp = isInner(ipNum,aBegin,aEnd) || isInner(ipNum,bBegin,bEnd) || isInner(ipNum,cBegin,cEnd)|| isInner(ipNum,dBegin,dEnd) || ipAddress.equals("127.0.0.1") || ipAddress.equals("255.255.255.255") || ipAddress.equals("224.0.0.1") || ipAddress.equals("0.0.0.0");
    	
        return isInnerIp;               
	} 

	/*
	 * If userIp's value between begin and end then return true.
	 * */
	private static boolean isInner(long userIp,long begin,long end)
	{    
	     return (userIp>=begin) && (userIp<=end);    
	}

3. Check If A String Is Public IP

	/* Checkout whether ipStr is a public network ip.
	 * ipStr : String ip address.
	 * return : true means ipStr is a public network ip, false means ipStr is not a public network ip. 
	 * */
	public static boolean isPublicInternetIp(String ipStr)
	{
		boolean ret = true;
		
		if(StringTool.isEmpty(ipStr))
		{
			ret = false;
		}else
		{
			ipStr = ipStr.trim();
			// If ip is not valid return false.
			if(!URLTool.isValidIp(ipStr))
			{
				ret = false;
			}else
			{
				//If ip is reserved local network address ip return false.
				if(ipStr.startsWith("0.") || ipStr.startsWith("10.") || ipStr.startsWith("127.") || ipStr.startsWith("192.168.")  || ipStr.startsWith("169.254."))
				{
					ret = false;
				}else
				{
					// Split ip address into four parts array.
					String ipColumnArr[] = ipStr.split(GeneralConstants.SEPERATOR_DOT);
					// If the array dose not include four parts return false.
					if(ipColumnArr.length!=4)
					{
						ret = false;
					}else
					{
						String ipC0 = ipColumnArr[0];
						String ipC1 = ipColumnArr[1];
						String ipC2 = ipColumnArr[2];
						String ipC3 = ipColumnArr[3];
						
						// If any part in ip address is not an integer.
						if(!StringTool.isInteger(ipC0) || !StringTool.isInteger(ipC1) || !StringTool.isInteger(ipC2) || !StringTool.isInteger(ipC3))
						{
							ret = false;
						}else
						{
							/*
							 * Check reserved ip address:
							 * 224.0.0.0 to 255.255.255.255
							 * 100.64.x.x－100.127.x.x[3]  、172.16.x.x－172.31.x.x、
							 * */
							// Check first two parts.
							int ipC0Int = Integer.parseInt(ipC0);
							int ipC1Int = Integer.parseInt(ipC1);
							
							// Filter out reserved ip address.
							if(ipC0Int >= 224)
							{
								ret = false;
							}else
							{
								if(ipC0Int==100)
								{
									if(ipC1Int>=64 && ipC1Int<=127) { ret = false; } }else if(ipC0Int==172) { if(ipC1Int>=16 && ipC1Int<=31)
									{
										ret = false;
									}
								}
							}
						}
					}
				}
			}
		}
		
		return ret;
	}