我得到了一个AsyncTask,应该检查对主机名的网络访问。但是doInBackground()永远不会超时。有人知道吗?

public class HostAvailabilityTask extends AsyncTask<String, Void, Boolean> {

    private Main main;

    public HostAvailabilityTask(Main main) {
        this.main = main;
    }

    protected Boolean doInBackground(String... params) {
        Main.Log("doInBackground() isHostAvailable():"+params[0]);

        try {
            return InetAddress.getByName(params[0]).isReachable(30); 
        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return false;       
    }

    protected void onPostExecute(Boolean... result) {
        Main.Log("onPostExecute()");

        if(result[0] == false) {
            main.setContentView(R.layout.splash);
            return;
        }

        main.continueAfterHostCheck();
    }   
}

当前回答

最好的方法:

public static boolean isOnline() {
    try {
    InetAddress.getByName("google.com").isReachable(3);

    return true;
    } catch (UnknownHostException e){
    return false;
    } catch (IOException e){
    return false;
    }
    }

其他回答

我使用这段代码而不是InetAddress:

    try {

        URL url = new URL("http://"+params[0]);

        HttpURLConnection urlc = (HttpURLConnection) url.openConnection();
        urlc.setRequestProperty("User-Agent", "Android Application:"+Z.APP_VERSION);
        urlc.setRequestProperty("Connection", "close");
        urlc.setConnectTimeout(1000 * 30); // mTimeout is in seconds
        urlc.connect();
        if (urlc.getResponseCode() == 200) {
            Main.Log("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();
    }

最简单的解决办法是

在大多数情况下,如果他/她想连接到远程服务器,只会检查互联网连接,所以简单和最好的解决方案是ping你的服务器,如下所示。

public boolean isConnected() {
    final String command = "ping -c 1 yourExmapleDomain.com";
    boolean isConnected = false;
    try {
        isConnected = Runtime.getRuntime().exec(command).waitFor() == 0;
    } catch (InterruptedException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return isConnected;
}

我已经经历了所有的答案,我想出了我自己的答案,首先检查互联网是否可用,如果互联网可用,然后检查它是否活跃。

我已经包括了所有必要的方法和类来检查活跃的Internet连接。

NetworkUtils.class

public class NetworkUtils {

    public static final int STATUS_CONNECTED = 0 ;

    public static boolean isInternetAvailable(Context ctx){
        ConnectivityManager cm = (ConnectivityManager)ctx.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
    }

    public static int isInternetActiveWithPing() {
        try {
            Runtime runtime = Runtime.getRuntime();
            Process process = runtime.exec("/system/bin/ping -c 1 8.8.8.8");
            int exitValue = process.waitFor();
            return exitValue;
        } catch (Exception ex) {
            return -1;
        }
    }

    public static boolean isInternetActiveWithInetAddress() {
        try {
            InetAddress inetAddress = InetAddress.getByName("www.google.com");
            return inetAddress != null && !inetAddress.toString().equals("");
        } catch (Exception ex) {
            return false;
        }
    }

    public static void displayInternetConnectionMessage(Context ctx){
        Toast.makeText(ctx, "Check Internet Connection", Toast.LENGTH_SHORT).show();
    }
}

你可以使用下面的代码检查互联网是否活跃:

 private void checkInternetConnection() {
        if (NetworkUtils.isInternetAvailable(this)) {
            new Thread(new Runnable() {
                @Override
                public void run() {
                    if (NetworkUtils.isInternetActiveWithPing() == NetworkUtils.STATUS_CONNECTED) {
                        performNetworkingOperations();
                    } else {
                        if (NetworkUtils.isInternetActiveWithInetAddress()) {
                            performNetworkingOperations();
                        } else {
                            displayConnectionMessage();
                        }
                    }
                }
            }).start();

        } else {
            displayConnectionMessage();
        }
    }

    private void performNetworkingOperations() {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Toast.makeText(MainActivity.this, "Internet is Available", Toast.LENGTH_SHORT).show();
            }
        });
    }

    private void displayConnectionMessage() {
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                NetworkUtils.displayInternetConnectionMessage(MainActivity.this);
            }
        });
    }

下面是我用于可达性检查的Kotlin版本,

芬兰湾的科特林MyReachability

object MyReachability {

    private val REACHABILITY_SERVER = "http://google.com" // can be any URL you want

    private fun hasNetworkAvailable(context: Context): Boolean {
        val service = Context.CONNECTIVITY_SERVICE
        val manager = context.getSystemService(service) as ConnectivityManager?
        val network = manager?.activeNetworkInfo
        Log.d(classTag, "hasNetworkAvailable: ${(network != null)}")
        return (network != null)
    }

    fun hasInternetConnected(context: Context): Boolean {
        if (hasNetworkAvailable(context)) {
            try {
                val connection = URL(REACHABILITY_SERVER).openConnection() as HttpURLConnection
                connection.setRequestProperty("User-Agent", "Test")
                connection.setRequestProperty("Connection", "close")
                connection.connectTimeout = 1500
                connection.connect()
                Log.d(classTag, "hasInternetConnected: ${(connection.responseCode == 200)}")
                return (connection.responseCode == 200)
            } catch (e: IOException) {
                Log.e(classTag, "Error checking internet connection", e)
            }
        } else {
            Log.w(classTag, "No network available!")
        }
        Log.d(classTag, "hasInternetConnected: false")
        return false
    }
}

您甚至可以根据策略和限制将REACHABILITY_SERVER作为参数传递,例如,当您在中国时,您可以检查https://baidu.com而不是https://google.com。

调用示例中,

val webLoaderThread = Thread {
   if (MyReachability.hasInternetConnected(this)){
       runOnUiThread {
           //mWebView.loadUrl(LANDING_SERVER) // connected
       }
   } else {
       runOnUiThread {
           //showDialogNoNetwork() // not connected
       }
   }
}
webLoaderThread.start()

安卓系统权限

不要忘记将以下权限添加到你的AndroidManifest.xml中

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
public boolean isNetworkAvailable(Context context) {
    ConnectivityManager connectivityManager
            = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null && activeNetworkInfo.isConnected();
}

以下是您需要的许可:

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