Android - 检查互联网访问

Question

我已阅读有关在 Android 中获取 Internet 连接状态的答案：

https://stackoverflow.com/a/22256277/4225644

但是它不能正常工作，例如如果我有一个没有互联网访问的网络连接，这个方法需要很长时间才能返回 False：

public Boolean isOnline() {
try {
    Process p1 = java.lang.Runtime.getRuntime().exec("ping -c 1 www.google.com");
    int returnVal = p1.waitFor();
    boolean reachable = (returnVal==0);
    return reachable;
} catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
return false;
}

我怎样才能减少这个时间以获得更快的答案？

Answer 1

使用此代码：

public static boolean isInternetConnected(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);

    NetworkInfo ni = cm.getActiveNetworkInfo();

    if (ni == null)
        return false;
    else {
        if (ni.isConnected())
            if (isOnline(context))
                return true;
            else
                return false;
        return false;
    }
}


public static boolean isOnline(Context context) {
    ConnectivityManager cm = (ConnectivityManager) context
            .getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    if (netInfo != null && netInfo.isConnected()) {
        try {
            URL url = new URL("http://www.google.com");
            HttpURLConnection urlc = (HttpURLConnection) url
                    .openConnection();
            urlc.setConnectTimeout(2000);
            urlc.connect();
            if (urlc.getResponseCode() == 200) {
                return new Boolean(true);
            }
        } catch (MalformedURLException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    return false;
}

Answer 2

您可以检查是否与

ConnectivityManager cm =
        (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null &&
                      activeNetwork.isConnectedOrConnecting();

这肯定是一种更快的方法来确定是否有网络访问，而不是执行请求并等待失败。

也请参阅文档。

Answer 3

如果您想检查互联网是否存在，此代码可能对您有所帮助

public boolean isConnectingToInternet(){
  ConnectivityManager connectivity = (ConnectivityManager)_context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity != null) 
  {
  NetworkInfo[] info = connectivity.getAllNetworkInfo();
  if (info != null) 
      for (int i = 0; i < info.length; i++) 
          if (info[i].getState() == NetworkInfo.State.CONNECTED)
          {
              return true;
          }

     }
   return false;
 }

并在您的manifest.xml授予权限

<uses-permission android:name="android.permission.INTERNET" />