检测Android设备是否具有Internet连接-Java 学习之路

127

我需要告诉我的设备是否有Internet连接 . 我找到了许多答案，如：

private boolean isNetworkAvailable() {
    ConnectivityManager connectivityManager 
         = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null;
}

（摘自检测Android上是否有可用的Internet连接 . ）

但这不对，例如，如果我 connected to a wireless network which doesn't have Internet access ，这个方法将返回true ... Is there a way to tell if the device has Internet connection and not if it is only connected to something?

9 回答

176

你是对的 . 您提供的代码仅检查是否存在网络连接 . 检查是否存在活动Internet连接的最佳方法是尝试通过http连接到已知服务器 .

public static boolean hasActiveInternetConnection(Context context) {
    if (isNetworkAvailable(context)) {
        try {
            HttpURLConnection urlc = (HttpURLConnection) (new URL("http://www.google.com").openConnection());
            urlc.setRequestProperty("User-Agent", "Test");
            urlc.setRequestProperty("Connection", "close");
            urlc.setConnectTimeout(1500); 
            urlc.connect();
            return (urlc.getResponseCode() == 200);
        } catch (IOException e) {
            Log.e(LOG_TAG, "Error checking internet connection", e);
        }
    } else {
        Log.d(LOG_TAG, "No network available!");
    }
    return false;
}

当然，您可以将 http://www.google.com URL替换为您要连接的任何其他服务器，或者您知道的服务器具有良好的正常运行时间 .

正如Tony Cho在this comment below中指出的那样，请确保您不会获得NetworkOnMainThread异常（在Android 3.0或更高版本中） . 请改用AsyncTask或Runnable .

如果你想使用google.com，你应该看看Jeshurun的修改 . 在his answer中，他修改了我的代码并使其更有效率 . 如果你连接到

HttpURLConnection urlc = (HttpURLConnection) 
            (new URL("http://clients3.google.com/generate_204")
            .openConnection());

然后检查204的响应代码

return (urlc.getResponseCode() == 204 && urlc.getContentLength() == 0);

那么你不必先获取整个谷歌主页 .

回复于 2024-04-29T22:57:25+08:00

我稍微修改了THelper的答案，使用Android已经用来检查连接的WiFi网络是否可以访问Internet的已知黑客 . 这比 grab 整个Google主页更有效率 . 有关详细信息，请参阅here和here .

public static boolean hasInternetAccess(Context context) {
    if (isNetworkAvailable(context)) {
        try {
            HttpURLConnection urlc = (HttpURLConnection) 
                (new URL("http://clients3.google.com/generate_204")
                .openConnection());
            urlc.setRequestProperty("User-Agent", "Android");
            urlc.setRequestProperty("Connection", "close");
            urlc.setConnectTimeout(1500); 
            urlc.connect();
            return (urlc.getResponseCode() == 204 &&
                        urlc.getContentLength() == 0);
        } catch (IOException e) {
            Log.e(TAG, "Error checking internet connection", e);
        }
    } else {
        Log.d(TAG, "No network available!");
    }
    return false;
}

回复于 2024-04-29T22:57:25+08:00

public boolean isInternetWorking() {
    boolean success = false;
    try {
        URL url = new URL("https://google.com");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setConnectTimeout(10000);
        connection.connect();
        success = connection.getResponseCode() == 200;
    } catch (IOException e) {
        e.printStackTrace();
    }
    return success;
}

如果互联网实际可用，则返回true

确保您拥有这两项权限

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

回复于 2024-04-29T22:57:25+08:00

如果您的目标是Lollipop或更高版本，则可以使用新的NetworkCapabilities类，即：

public static boolean hasInternetConnection(final Context context) {
    final ConnectivityManager connectivityManager = (ConnectivityManager)context.
            getSystemService(Context.CONNECTIVITY_SERVICE);

    final Network network = connectivityManager.getActiveNetwork();
    final NetworkCapabilities capabilities = connectivityManager
            .getNetworkCapabilities(network);

    return capabilities != null
            && capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED);
}

回复于 2024-04-29T22:57:25+08:00

试试这个

public class ConnectionDetector {
    private Context _context;

    public ConnectionDetector(Context context) {
        this._context = context;
    }

    public boolean isConnectingToInternet() {
        if (networkConnectivity()) {
            try {
                HttpURLConnection urlc = (HttpURLConnection) (new URL(
                        "http://www.google.com").openConnection());
                urlc.setRequestProperty("User-Agent", "Test");
                urlc.setRequestProperty("Connection", "close");
                urlc.setConnectTimeout(3000);
                urlc.setReadTimeout(4000);
                urlc.connect();
                // networkcode2 = urlc.getResponseCode();
                return (urlc.getResponseCode() == 200);
            } catch (IOException e) {
                return (false);
            }
        } else
            return false;

    }

    private boolean networkConnectivity() {
        ConnectivityManager cm = (ConnectivityManager) _context
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = cm.getActiveNetworkInfo();
        if (networkInfo != null && networkInfo.isConnected()) {
            return true;
        }
        return false;
    }
}

您必须将以下权限添加到清单文件中：

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

然后这样打电话：

if((new ConnectionDetector(MyService.this)).isConnectingToInternet()){
    Log.d("internet status","Internet Access");
}else{
    Log.d("internet status","no Internet Access");
}

回复于 2024-04-29T22:57:25+08:00

您不一定需要 Build 完整的HTTP连接 . 您可以尝试只打开与已知主机的TCP连接，如果成功，则可以连接互联网 .

public boolean hostAvailable(String host, int port) {
  try (Socket socket = new Socket()) {
    socket.connect(new InetSocketAddress(host, port), 2000);
    return true;
  } catch (IOException e) {
    // Either we have a timeout or unreachable host or failed DNS lookup
    System.out.println(e);
    return false;
  }
}

然后检查：

boolean online = hostAvailable("www.google.com", 80);

回复于 2024-04-29T22:57:25+08:00

根据接受的答案，我用一个监听器构建了这个类，所以你可以在主线程中使用它：

First ：InterntCheck类在后台检查互联网连接，然后使用结果调用侦听器方法 .

public class InternetCheck extends AsyncTask<Void, Void, Void> {


    private Activity activity;
    private InternetCheckListener listener;

    public InternetCheck(Activity x){

        activity= x;

    }

    @Override
    protected Void doInBackground(Void... params) {


        boolean b = hasInternetAccess();
        listener.onComplete(b);

        return null;
    }


    public void isInternetConnectionAvailable(InternetCheckListener x){
        listener=x;
        execute();
    }

    private boolean isNetworkAvailable() {
        ConnectivityManager connectivityManager = (ConnectivityManager) activity.getSystemService(CONNECTIVITY_SERVICE);
        NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
        return activeNetworkInfo != null;
    }
    private boolean hasInternetAccess() {
        if (isNetworkAvailable()) {
            try {
                HttpURLConnection urlc = (HttpURLConnection) (new URL("http://clients3.google.com/generate_204").openConnection());
                urlc.setRequestProperty("User-Agent", "Android");
                urlc.setRequestProperty("Connection", "close");
                urlc.setConnectTimeout(1500);
                urlc.connect();
                return (urlc.getResponseCode() == 204 &&
                        urlc.getContentLength() == 0);
            } catch (IOException e) {
                e.printStackTrace();
            }
        } else {
            Log.d("TAG", "No network available!");
        }
        return false;
    }

    public interface InternetCheckListener{
        void onComplete(boolean connected);
    }

}

Second ：在主线程中实例化一个类的实例并等待响应（如果你已经使用过Firebase api for android，那么你应该熟悉它！） .

new InternetCheck(activity).isInternetConnectionAvailable(new InternetCheck.InternetCheckListener() {

        @Override
        public void onComplete(boolean connected) {
           //proceed!
        }
    });

现在在onComplete方法中，您将获得设备是否已连接到互联网 .

回复于 2024-04-29T22:57:25+08:00

private static NetworkUtil mInstance;
private volatile boolean mIsOnline;

private NetworkUtil() {
    ScheduledExecutorService exec = Executors.newSingleThreadScheduledExecutor();
    exec.scheduleAtFixedRate(new Runnable() {
        @Override
        public void run() {
            boolean reachable = false;
            try {
                Process process = java.lang.Runtime.getRuntime().exec("ping -c 1 www.google.com");
                int returnVal = process.waitFor();
                reachable = (returnVal==0);
            } catch (Exception e) {
                e.printStackTrace();
            }
            mIsOnline = reachable;
        }
    }, 0, 5, TimeUnit.SECONDS);
}

public static NetworkUtil getInstance() {
    if (mInstance == null) {
        synchronized (NetworkUtil.class) {
            if (mInstance == null) {
                mInstance = new NetworkUtil();
            }
        }
    }
    return mInstance;
}

public boolean isOnline() {
    return mIsOnline;
}

希望上面的代码可以帮助您，同时确保您在我的应用程序中拥有互联网权限 .

回复于 2024-04-29T22:57:25+08:00

从documentation执行此操作的最新方法是使用 ConnectivityManager 查询活动网络并确定它是否具有Internet连接 .

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

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

将这两个权限添加到AndroidManifest.xml文件中：

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

回复于 2024-04-29T22:57:25+08:00

检测Android设备是否具有Internet连接

9 回答

相关问题