Effective way to check for slow internet connection and differentiate between network connection and actual internet connection in android

问题

How to check if the device is connected to internet or it is just connected to external wifi network? Because NetworkInfo returns true if a device is connected to an external wifi network even there is no network connection.

When device is connected to wifi but there is no internet access,my app's network connectivity-check class returns true but application crashes with the exception that it cannot access the corresponding http url.

回答1:

If you want to know when you have an active internet connection, do something like this:

Some static variables:

/**
 * Set the number of retries when reestablishing Internet connection.
 */
private static int retryConnectionNumber = 0;

/**
 * The maximum number of retries allowed for Internet connection.
 */
private final static int CONNECTION_RETRY_MAX = 5;

/**
 * The timeout of the HTTP request when checking for Internet connection.
 */
private final static int REQUEST_TIMEOUT = 2000;

The method to check if network is available:

private static void isNetworkAvailable(final Handler handler,
            final int timeout) {
        new Thread() {
            private boolean responded = false;

            @Override
            public void run() {
                URL url = null;
                try {
                    url = new URL("http://your_server_addres.com");
                } catch (MalformedURLException e1) {
                    e1.printStackTrace();
                }
                String host = "";
                if (null != url) {
                    host = url.getHost();
                }

                Log.i("NetworkCheck", "[PING] host: " + host);
                Process process = null;
                try {
                    process = new ProcessBuilder()
                            .command("/system/bin/ping", "-c 1",
                                    "-w " + (timeout / 1000), "-n", host)
                            .redirectErrorStream(true).start();
                } catch (IOException e) {
                    e.printStackTrace();
                }

                InputStream in = process.getInputStream();
                StringBuilder s = new StringBuilder();
                int i;

                try {
                    while ((i = in.read()) != -1) {
                        s.append((char) i);

                        if ((char) i == '\n') {
                            Log.i("NetworkCheck",
                                    "[PING] log: " + s.toString());
                            if (s.toString().contains("64 bytes from")) {
                                // If there were a response from the server at
                                // all, we have Internet access
                                responded = true;
                            }
                            s.delete(0, s.length());
                        }
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    // Destroy the PING process
                    process.destroy();

                    try {
                        // Close the input stream - avoid memory leak
                        in.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                    // Send the response to the handler, 1 for success, 0
                    // otherwise
                    handler.sendEmptyMessage(!responded ? 0 : 1);
                }
            }
        }.start();
    }

The handler:

/**
 * Handler used that receives the connection status for the Internet.
 * If no active Internet connection will retry #CONNECTION_RETRY_MAX times
 */
private static Handler listenForNetworkAvailability = new Handler() {
    @Override
    public void handleMessage(Message msg) {
        if (msg.what != 1) { // code if not connected
            Log.i("NetworkCheck", "not connected");

            if (retryConnectionNumber <= CONNECTION_RETRY_MAX) {
                Log.i("NetworkCheck", "checking for connectivity");
                Here you could disable & re-enable your WIFI/3G connection before retry

                // Start the ping process again with delay
                Handler handler = new Handler();
                handler.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        isNetworkAvailable(listenForNetworkAvailability, REQUEST_TIMEOUT);
                    }
                }, 5000);
                retryConnectionNumber++;
            } else {
                Log.i("NetworkCheck", "failed to establish an connection");
                // code if not connected
            }
        } else {            
            Log.i("NetworkCheck", "connected");
            retryConnectionNumber = 0;
            // code if connected
        }
    }
}

回答2:

Something like this would work:

private boolean haveNetworkConnection() {
        boolean haveConnectedWifi = false;
        boolean haveConnectedMobile = false;

        ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo[] netInfo = cm.getAllNetworkInfo();
        for (NetworkInfo ni : netInfo) {
            if (ni.getTypeName().equalsIgnoreCase("WIFI"))
                if (ni.isConnected())
                    haveConnectedWifi = true;
            if (ni.getTypeName().equalsIgnoreCase("MOBILE"))
                if (ni.isConnected())
                    haveConnectedMobile = true;
        }
        return haveConnectedWifi || haveConnectedMobile;
    }

I have copied this code from here (I understand the code - I am just adding the code here for ease for the user + I got told by an admin that you should do this and credit the original post). Personally I would split this into two functions, one for mobile and one for wifi, but that choice is up to you.

来源：https://stackoverflow.com/questions/25309603/effective-way-to-check-for-slow-internet-connection-and-differentiate-between-ne