NSD Android - Network discovery

Question

Hello I am new to Android Development. I have created an NSD Utility class. Currently its unable to call the method DiscoveryListner. Any help will be great

MainActivity

package com.example.android.implicitintents;

import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

import com.example.android.implicitintents.Utils.NsdUtils;

import java.net.URL;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "NsdChat";
    public static String URL_WEB;
    NsdUtils mNsdUtils;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        NsdUtils mNsdUtils = new NsdUtils(this);
        mNsdUtils.initializeNsd();
    }

    public void onClickOpenWebpageButton(View view) {
        String urlAsString = "http://192.168.10.1";
        openWebPage(urlAsString);
    }


    private void openWebPage(String url) {
        Intent intent = new Intent(this, ConfigActivity.class);
        intent.putExtra(URL_WEB, url);
        Log.d(TAG, "Button Pressed");

        if (intent.resolveActivity(getPackageManager()) != null) {
            startActivity(intent);
        }
    }
}

NSD Utility Class

package com.example.android.implicitintents.Utils;

import android.content.Context;
import android.net.nsd.NsdServiceInfo;
import android.net.nsd.NsdManager;
import android.util.Log;

public class NsdUtils {
    Context mContext;

    NsdManager mNsdManager;
    NsdManager.ResolveListener mResolveListener;
    NsdManager.DiscoveryListener mDiscoveryListener;

    public static final String SERVICE_TYPE = "http";

    public static final String TAG = "NsdHelper";
    public String mServiceName = "Plug_Service";

    NsdServiceInfo mService;

    public NsdUtils(Context context) {
        mContext = context;
        mNsdManager = (NsdManager) context.getSystemService(Context.NSD_SERVICE);
    }

    public void initializeNsd() {
        initializeResolveListener();
        initializeDiscoveryListener();
    }

    public void initializeDiscoveryListener() {
        mDiscoveryListener = new NsdManager.DiscoveryListener() {

            @Override
            public void onDiscoveryStarted(String regType) {
                Log.d(TAG, "Service discovery started");
            }

            @Override
            public void onServiceFound(NsdServiceInfo service) {
                Log.d(TAG, "Service discovery success" + service);
                if (!service.getServiceType().equals(SERVICE_TYPE)) {
                    Log.d(TAG, "Unknown Service Type: " + service.getServiceType());
                } else if (service.getServiceName().equals(mServiceName)) {
                    Log.d(TAG, "Same machine: " + mServiceName);
                } else if (service.getServiceName().contains(mServiceName)){
                    mNsdManager.resolveService(service, mResolveListener);
                }
            }

            @Override
            public void onServiceLost(NsdServiceInfo service) {
                Log.e(TAG, "service lost" + service);
                if (mService == service) {
                    mService = null;
                }
            }

            @Override
            public void onDiscoveryStopped(String serviceType) {
                Log.i(TAG, "Discovery stopped: " + serviceType);
            }

            @Override
            public void onStartDiscoveryFailed(String serviceType, int errorCode) {
                Log.e(TAG, "Discovery failed: Error code:" + errorCode);
                mNsdManager.stopServiceDiscovery(this);
            }

            @Override
            public void onStopDiscoveryFailed(String serviceType, int errorCode) {
                Log.e(TAG, "Discovery failed: Error code:" + errorCode);
                mNsdManager.stopServiceDiscovery(this);
            }
        };
    }

    public void initializeResolveListener() {
        mResolveListener = new NsdManager.ResolveListener() {

            @Override
            public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode) {
                Log.e(TAG, "Resolve failed" + errorCode);
            }

            @Override
            public void onServiceResolved(NsdServiceInfo serviceInfo) {
                Log.e(TAG, "Resolve Succeeded. " + serviceInfo);

                if (serviceInfo.getServiceName().equals(mServiceName)) {
                    Log.d(TAG, "Same IP.");
                    return;
                }
                mService = serviceInfo;
            }
        };
    }
    public void discoverServices() {
        mNsdManager.discoverServices(
                SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, mDiscoveryListener);
    }
}

I tried calling the dicoverService in onclick button event in failed. Do we need to create a Async Task or a new Thread?

Answer 1

first specify the type of TCP network you want to find. Then make the object of the class and call the Intilization and then the discovery function of the NSD.

It should work just fine.

Answer 2

It is not necessary to run this functionality in another thread. After some investigation current functionality stop crash and start discovery, when change String SERVICE_TYPE = "http"; to public static final String SERVICE_TYPE = "_name._tcp";

You can discover tcp service and then when you will obtain IP just connect to web server via http use those IP adress.