java代码实现判断是否能ping通

package socket;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.InetAddress;
import java.net.UnknownHostException;

public class TestSocket {
	public static void main(String[] args) throws IOException {
		StringBuilder sb1 = new StringBuilder();
		for (int i = 0; i < 5; i++) {
			Process p = Runtime.getRuntime().exec("ping " + "192.168.16."+ i);
			InputStream is = p.getInputStream();
			InputStreamReader isr = new InputStreamReader(is);
			BufferedReader br = new BufferedReader(isr);
			String line = null;
			StringBuilder sb = new StringBuilder();
			while((line = br.readLine())!=null) {
				sb.append(line);
			}
			if(null != sb && !sb.toString().equals("")) {
				String longString = "";
				if(sb.toString().indexOf("TTL")>0) {
					sb1.append("ping " + "192.168.16."+ i);
				}
				else {
					System.out.println("ping " + "192.168.16."+ i +"无法ping通");
				}
			}
		}
		System.out.println("以下可以ping通");
		System.out.println(sb1.toString());
	}
}

其实最主要的代码段是

if(null != sb && !sb.toString().equals("")) {
				String longString = "";
				if(sb.toString().indexOf("TTL")>0) {//能ping通过则有TTL字段，返回的index大于0
					sb1.append("ping " + "192.168.16."+ i);
				}
}

参考部分函数，indexof的用法