java判断网络连接是否正常

/**
     * 判断本机当前的网络状态是否联通
     * 在这里主要用到中国天气信息，所以访问百度地址是否能够访问成功来判断当前的网络状态
     */
    public static boolean isConnect() {
        Runtime runtime = Runtime.getRuntime();
        try {
            Process 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);
            }
            is.close();
            isr.close();
            br.close();
 
            if (null != sb && !sb.toString().equals("")) {
                if (sb.toString().indexOf("TTL") > 0) {
                    //网络畅通
                    return true;
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        return false;
    }

原文：http://blog.csdn.net/huhui_cs/article/details/8813113