java通过ping 判断网络是否正常

 import java.io.BufferedReader;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;    

 /**
  * 判断网络连接状况.
  *
  */
 public class NetState {    

     public boolean isConnect(){
         boolean connect = false;
         Runtime runtime = Runtime.getRuntime();
         Process process;
         try {
             process = runtime.exec("ping " + "www.baidu.com");
             InputStream is = process.getInputStream();
             InputStreamReader isr = new InputStreamReader(is);
             BufferedReader br = new BufferedReader(isr);
             String line = null;
             StringBuffer sb = new StringBuffer();
             while ((line = br.readLine()) != null) {
                 sb.append(line);
             }
             System.out.println("返回值为:"+sb);
             is.close();
             isr.close();
             br.close();     

             if (null != sb && !sb.toString().equals("")) {
                 String logString = "";
                 if (sb.toString().indexOf("TTL") > 0) {
                     // 网络畅通
                     connect = true;
                 } else {
                     // 网络不畅通
                     connect = false;
                 }
             }
         } catch (IOException e) {
             e.printStackTrace();
         }
         return connect;
     }    

     public static void main(String[] args) {
         NetState netState = new NetState();
         System.out.println(netState.isConnect());    

     }
 }