代码:

    fun isInternetConnection(): Boolean {
    var returnVal = false
    thread {
        returnVal = try {
            khttp.get("https://www.google.com/")
            true
        }catch (e:Exception){
            false
        }
    }.join()
    return returnVal
}

Gradle:

implementation 'io.karn:khttp-android:0.1.0'

我使用khttp是因为它很容易使用。

在上面的代码中，如果它成功连接到google.com，它返回true否则为false。很简单。我不明白为什么每个人都要写这么长的代码，即使是为了这么简单的事情。

代码:

    fun isInternetConnection(): Boolean {
    var returnVal = false
    thread {
        returnVal = try {
            khttp.get("https://www.google.com/")
            true
        }catch (e:Exception){
            false
        }
    }.join()
    return returnVal
}

Gradle:

implementation 'io.karn:khttp-android:0.1.0'

我使用khttp是因为它很容易使用。

在上面的代码中，如果它成功连接到google.com，它返回true否则为false。很简单。我不明白为什么每个人都要写这么长的代码，即使是为了这么简单的事情。

public class Network {

Context context;

public Network(Context context){
    this.context = context;
}

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

    NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
    return activeNetwork != null &&
                          activeNetwork.isConnectedOrConnecting();
}

}

这对我很有用。试试吧。

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    try {
        URL url = new URL("http://stackoverflow.com/posts/11642475/edit" );
        //URL url = new URL("http://www.nofoundwebsite.com/" );
        executeReq(url);
        Toast.makeText(getApplicationContext(), "Webpage is available!", Toast.LENGTH_SHORT).show();
    }
    catch(Exception e) {
        Toast.makeText(getApplicationContext(), "oops! webpage is not available!", Toast.LENGTH_SHORT).show();
    }
}

private void executeReq(URL urlObject) throws IOException
{
    HttpURLConnection conn = null;
    conn = (HttpURLConnection) urlObject.openConnection();
    conn.setReadTimeout(30000);//milliseconds
    conn.setConnectTimeout(3500);//milliseconds
    conn.setRequestMethod("GET");
    conn.setDoInput(true);

    // Start connect
    conn.connect();
    InputStream response =conn.getInputStream();
    Log.d("Response:", response.toString());
}}

The other answers that use ConnectivityManager are wrong because having a network connection doesn't mean you have internet access. For example, the user might be connected to a coffee shop's WiFi portal but can't get to the internet. To check that the internet is accessible you have to try to connect to an actual server. Normally when you want to do this you have a specific server in mind that you want to connect to, so go ahead and check if you can connect to that server. Here's a simple method for checking connectivity to a server.

private boolean isOnTheInternet() {
    try {
        URLConnection urlConnection = new URL("http://yourserver").openConnection();
        urlConnection.setConnectTimeout(400);
        urlConnection.connect();
        return true;
    } catch (Exception e) {
        return false;
    }
}

设置ConnectTimeout的原因是，否则它默认为TCP超时，可以有很多秒长。

还要注意的是，Android不允许你在主线程上运行这个程序。

要让getActiveNetworkInfo()工作，您需要向清单中添加以下内容。

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