package book.string;

public class IP2Long {
	//將127.0.0.1 形式的IP地址轉(zhuǎn)換成10進制整數(shù)，這里沒有進行任何錯誤處理
    public static long ipToLong(String strIP){
         long[] ip=new long[4];
         //先找到IP地址字符串中.的位置
         int position1=strIP.indexOf(".");
         int position2=strIP.indexOf(".",position1+1);
         int position3=strIP.indexOf(".",position2+1);
         //將每個.之間的字符串轉(zhuǎn)換成整型
         ip[0]=Long.parseLong(strIP.substring(0,position1));
         ip[1]=Long.parseLong(strIP.substring(position1+1,position2));
         ip[2]=Long.parseLong(strIP.substring(position2+1,position3));
         ip[3]=Long.parseLong(strIP.substring(position3+1));
         return (ip[0]<<24)+(ip[1]<<16)+(ip[2]<<8)+ip[3]; 
    }

    //將10進制整數(shù)形式轉(zhuǎn)換成127.0.0.1形式的IP地址
    public static String longToIP(long longIP){
         StringBuffer sb=new StringBuffer("");
         //直接右移24位
         sb.append(String.valueOf(longIP>>>24));
         sb.append(".");          
         //將高8位置0，然后右移16位
         sb.append(String.valueOf((longIP&0x00FFFFFF)>>>16)); 
         sb.append(".");
         sb.append(String.valueOf((longIP&0x0000FFFF)>>>8));
         sb.append(".");
         sb.append(String.valueOf(longIP&0x000000FF));
         return sb.toString(); 
    } 
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		String ipStr = "192.168.0.1";
		long ipLong = IP2Long.ipToLong(ipStr);
		System.out.println("192.168.0.1 的整數(shù)形式為: " + ipLong);
		System.out.println("整數(shù)" + ipLong + "轉(zhuǎn)化成字符串IP地址: " 
				+ IP2Long.longToIP(ipLong));
		//IP地址轉(zhuǎn)化成二進制形式輸出
		System.out.println("192.168.0.1 的二進制形式為: " 
				+ Long.toBinaryString(ipLong));
	}
}