获取内网范围内所有IP

界面如上：

package net;

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.HashMap;
import java.util.Map;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class GainAllIp extends JFrame{
	public GainAllIp(){

		panel.setLayout(new FlowLayout());
		panel.add(showButton);
		panel.add(closeButton);

		JScrollPane js = new JScrollPane(textArea,
				JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
				JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);

		panel.add(js);
		add(panel);

		showButton.addActionListener(new ActionListener(){
			@Override
			public void actionPerformed(ActionEvent e){
				try{
					gainAllIp();
				}catch(UnknownHostException e1){
					e1.printStackTrace();
				}
			}
		});
		closeButton.addActionListener(new ActionListener(){
			@Override
			public void actionPerformed(ActionEvent e){
				System.exit(0);
			}
		});
		setSize(300, 300);
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}

	/**
	 * 获取内网所有IP，并显示在文本域中
	 * 
	 * @throws UnknownHostException
	 * */
	public void gainAllIp() throws UnknownHostException{
		InetAddress host = InetAddress.getLocalHost();
		String hostAddress = host.getHostAddress();
		int pos = hostAddress.lastIndexOf(".");
		String wd = hostAddress.substring(0, pos + 1);
		for(int i = 1; i <= 255; ++i){
			String ip = wd + i;
			thread = new PingIpThread(ip);
			new Thread(thread).start();
		}
	}

	/**
	 * 内部线程类 用于Ping指定的Ip地址，并判断其是否为有效的内网Ip地址，如果是就添加在集合对象中
	 * */
	class PingIpThread implements Runnable{
		public PingIpThread(){

		}

		public PingIpThread(String ip){
			this.ip = ip;
		}

		private String ip;

		@Override
		public void run(){
			try{
				// 获取所ping的IP进程
				Process pro = Runtime.getRuntime().exec(
						"ping " + ip + " -w 280 -n 1");
				BufferedReader buf = new BufferedReader(new InputStreamReader(
						pro.getInputStream()));
				String line = buf.readLine();
				while(line != null){
					if(line != null && (!line.equals(""))){
						if(line.substring(0, 2).equals("来自")
								|| (line.length() > 10 && line.substring(0, 10)
										.equals("Reply from"))){
							textArea.append(ip + "\n");
							System.out.println(ip);
						}
					}
					line = buf.readLine();
				}
			}catch(Exception e){
				e.printStackTrace();
			}

		}
	}// end inner class

	public static void main(String[] args){
		new GainAllIp();
	}

	JPanel panel = new JPanel();
	JButton showButton = new JButton("显示所有内网IP");
	JButton closeButton = new JButton("退出程序");
	JTextArea textArea = new JTextArea(15, 20);
	Map<String, String> pingmap = new HashMap<String, String>();
	PingIpThread thread = null;
}