ping外网

/**
     * @author suncat
     * @category 判断是否有外网连接（普通方法不能判断外网的网络是否连接，比如连接上局域网）
     * @return
     */
    public static final boolean ping() {

        String result = null;
        try {
                String ip = "www.baidu.com";// ping 的地址，可以换成任何一种可靠的外网
                Process p = Runtime.getRuntime().exec("ping -c 3 -w 100 " + ip);// ping网址3次
                // 读取ping的内容，可以不加
                InputStream input = p.getInputStream();
                BufferedReader in = new BufferedReader(new InputStreamReader(input));
                StringBuffer stringBuffer = new StringBuffer();
                String content = "";
                while ((content = in.readLine()) != null) {
                        stringBuffer.append(content);
                }
                Log.d("------ping-----", "result content : " + stringBuffer.toString());
                // ping的状态
                int status = p.waitFor();
                if (status == 0) {
                        result = "success";
                        return true;
                } else {
                        result = "failed";
                }
        } catch (IOException e) {
                result = "IOException";
        } catch (InterruptedException e) {
                result = "InterruptedException";
        } finally {
                Log.d("----result---", "result = " + result);
        }
        return false;
}