Apache commons net 项目中封装了各种网络协议的客户端，支持的协议包括：

·        FTP

·        NNTP

·        SMTP

·        POP3

·        Telnet

·        TFTP

·        Finger

·        Whois

·        rexec/rcmd/rlogin

·        Time (rdate) andDaytime

·        Echo

·        Discard

·        NTP/SNTP

目前最新的版本为3.3.

和httpclient相比，net包更加侧重各种网络协议的使用，很多是专业网络方面的知识，对不了解的这些网络特性的情况，很难理解这些包的具体含义。

总而言之，这是一个强大的类，这是一个富有生命力，有专业精神的类。 ：)

import java.util.Arrays;

import java.util.Scanner;

import org.apache.commons.net.util.SubnetUtils;

import org.apache.commons.net.util.SubnetUtils.SubnetInfo;

/**

* Example class that shows how to use the [email protected] SubnetUtils} class.

* @author Rory Winston

*

*/

public classSubnetUtilsExample {

public static void main(String[] args) {

String subnet = "192.168.38.1/31";

SubnetUtils utils = new SubnetUtils(subnet);

SubnetInfo info = utils.getInfo();

System.out.printf("Subnet Information for %s:\n",subnet);

System.out.println("--------------------------------------");

System.out.printf("IP Address:\t\t\t%s\t[%s]\n",info.getAddress(),

Integer.toBinaryString(info.asInteger(info.getAddress())));

System.out.printf("Netmask:\t\t\t%s\t[%s]\n",info.getNetmask(),

Integer.toBinaryString(info.asInteger(info.getNetmask())));

System.out.printf("CIDR Representation:\t\t%s\n\n",info.getCidrSignature());

System.out.printf("Supplied IP Address:\t\t%s\n\n",info.getAddress());

System.out.printf("Network Address:\t\t%s\t[%s]\n",info.getNetworkAddress(),

Integer.toBinaryString(info.asInteger(info.getNetworkAddress())));

System.out.printf("Broadcast Address:\t\t%s\t[%s]\n",info.getBroadcastAddress(),

Integer.toBinaryString(info.asInteger(info.getBroadcastAddress())));

System.out.printf("Low Address:\t\t\t%s\t[%s]\n",info.getLowAddress(),

Integer.toBinaryString(info.asInteger(info.getLowAddress())));

System.out.printf("High Address:\t\t\t%s\t[%s]\n",info.getHighAddress(),

Integer.toBinaryString(info.asInteger(info.getHighAddress())));

System.out.printf("Total usable addresses: \t%d\n",Integer.valueOf(info.getAddressCount()));

System.out.printf("Address List: %s\n\n", Arrays.toString(info.getAllAddresses()));

System.out.println("全部地址：" + Arrays.toString(info.getAllAddresses()));

final String prompt ="Enter an IP address (e.g. 192.168.0.10):";

System.out.println(prompt);

Scanner scanner = new Scanner(System.in);

while (scanner.hasNextLine()) {

String address =scanner.nextLine();

System.out.println("The IP address [" + address + "] is "

+ (info.isInRange(address)? "": "not ")

+ "within the subnet [" + subnet + "]");

System.out.println(prompt);

}

}

}

运行结果如下：

Subnet Information for 192.168.38.1/31:

--------------------------------------

IP Address:         192.168.38.1    [11000000101010000010011000000001]

Netmask:            255.255.255.254 [11111111111111111111111111111110]

CIDR Representation:        192.168.38.1/31

Supplied IP Address:        192.168.38.1

Network Address:        192.168.38.0    [11000000101010000010011000000000]

Broadcast Address:      192.168.38.1    [11000000101010000010011000000001]

Low Address:            0.0.0.0 [0]

High Address:           0.0.0.0 [0]

Total usable addresses:     0

Address List: []

全部地址：[]

Enter an IP address (e.g.192.168.0.10):