package helpfile;

public class IP2Long {
    
    //將127.0.0.1形式的IP地址轉(zhuǎn)換成十進制整數(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];
    }
    
    //將十進制整數(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(".");
        //將高16位置0，然后右移8位
        sb.append(String.valueOf((longIp & 0x0000FFFF) >>> 8));
        sb.append(".");
        //將高24位置0
        sb.append(String.valueOf((longIp & 0x000000FF)));
        return sb.toString();
    }
    /** *//**
     * @param args
     */
    public static void main(String[] args){
        String ipStr = "192.168.0.1";
        long longIp = IP2Long.ipToLong(ipStr);
        System.out.println("192.168.0.1 的整數(shù)形式為：" + longIp);
        System.out.println("整數(shù)" + longIp + "轉(zhuǎn)化成字符串IP地址："
                + IP2Long.longToIP(longIp));
        //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(longIp));

    }
}