示例程式碼：

/*
 * 網路通訊的第一個要素：IP地址。通過IP地址，唯一的定位網際網路上一臺主機
 * InetAddress:位於java.net包下
 * 1.InetAddress用來代表IP地址。一個InetAdress的物件就代表著一個IP地址
 * 2.如何建立InetAddress的物件：getByName(String host)
 * 3.getHostName(): 獲取IP地址對應的域名
 *   getHostAddress():獲取IP地址
 */
import java.net.InetAddress;
import java.net.UnknownHostException;

import org.junit.Test;

public class TestInetAddress {
	@Test
	public void testInetAddress() throws UnknownHostException {
		InetAddress inet = InetAddress.getByName("www.jmu.edu.cn");
		//inet = InetAddress.getByName("210.34.128.132");
		System.out.println(inet);//www.jmu.edu.cn/210.34.128.132
		System.out.println(inet.getHostName());//www.jmu.edu.cn
		System.out.println(inet.getHostAddress());//210.34.128.132
		
		//獲取本機的IP
		inet = InetAddress.getLocalHost();
		System.out.println(inet);
		System.out.println(inet.getHostName());
		System.out.println(inet.getHostAddress());
	}
}