我在学习developer.android.com的网络教程时遇到了一个问题。
(http://developer.android.com/training/connect-devices-wirelessly/nsd.html)
我出错了，有时我的手机就关机了。
下面是我的代码：

package com.example.networking;

import java.io.IOException;
import java.net.ServerSocket;

import javax.sound.sampled.Port;

import android.net.nsd.NsdManager;
import android.net.nsd.NsdManager.DiscoveryListener;
import android.net.nsd.NsdManager.RegistrationListener;
import android.net.nsd.NsdManager.ResolveListener;
import android.net.nsd.NsdServiceInfo;
import android.os.Bundle;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.Menu;

@SuppressLint("NewApi")
public class MainActivity extends Activity {

RegistrationListener mRegistrationListener;
    DiscoveryListener mDiscoveryListener;

    String mServiceName;
    NsdServiceInfo mServiceInfo;
    ServerSocket mServerSocket;
    int mLocalPort;

    NsdManager mNsdManager;

    final String TAG = "---Networking";
    final String SERVICE_TYPE = "_http._tcp.";

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

        // Initialize a server socket on the next available port.
        try {
            mServerSocket = new ServerSocket(0);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // Store the chosen port.
        mLocalPort =  mServerSocket.getLocalPort();

        registerService(mLocalPort);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public void registerService(int port) {
        // Create the NsdServiceInfo object, and populate it.
        mServiceInfo  = new NsdServiceInfo();

        // The name is subject to change based on conflicts
        // with other services advertised on the same network.
        mServiceInfo.setServiceName("NsdChat");
        mServiceInfo.setServiceType("_http._tcp.");
        mServiceInfo.setPort(port);

        mNsdManager = (NsdManager) getApplicationContext().getSystemService(Context.NSD_SERVICE);

        initializeRegistrationListener();
        initializeDiscoveryListener();

        mNsdManager.registerService(
                mServiceInfo, NsdManager.PROTOCOL_DNS_SD, mRegistrationListener);

        mNsdManager.discoverServices(
                SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, mDiscoveryListener);
    }

    public void initializeRegistrationListener() {
        mRegistrationListener = new NsdManager.RegistrationListener() {

            @Override
            public void onServiceRegistered(NsdServiceInfo NsdServiceInfo) {
                // Save the service name.  Android may have changed it in order to
                // resolve a conflict, so update the name you initially requested
                // with the name Android actually used.
                mServiceName = NsdServiceInfo.getServiceName();
                Log.d(TAG , "Service name: " + mServiceName);
                Log.d(TAG , "Port number: " + mLocalPort);
            }

            @Override
            public void onRegistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
                // Registration failed!  Put debugging code here to determine why.
                Log.d(TAG , "Registration Failed! Error code: " + errorCode);
            }

            @Override
            public void onServiceUnregistered(NsdServiceInfo arg0) {
                // Service has been unregistered.  This only happens when you call
                // NsdManager.unregisterService() and pass in this listener.
                Log.d(TAG , "Service unregistered.");
            }

            @Override
            public void onUnregistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
                // Unregistration failed.  Put debugging code here to determine why.
                Log.d(TAG , "Unregistration failed!");
            }
        };
    }

    public void initializeDiscoveryListener() {

        // Instantiate a new DiscoveryListener
        mDiscoveryListener = new NsdManager.DiscoveryListener() {

            //  Called as soon as service discovery begins.
            @Override
            public void onDiscoveryStarted(String regType) {
                Log.d(TAG , "Service discovery started");
            }

            @Override
            public void onServiceFound(NsdServiceInfo service) {
                // A service was found!  Do something with it.
                Log.d(TAG, "Service discovery success: " + service);
                if (!service.getServiceType().equals(SERVICE_TYPE)) {
                    // Service type is the string containing the protocol and
                    // transport layer for this service.
                    Log.d(TAG, "Unknown Service Type: " + service.getServiceType());
                } else if (service.getServiceName().equals(mServiceName)) {
                    // The name of the service tells the user what they'd be
                    // connecting to. It could be "Bob's Chat App".
                    Log.d(TAG, "Same machine: " + mServiceName);
                } else if (service.getServiceName().contains("NsdChat")){
                    mNsdManager.resolveService(service, new ResolveListener() {

                        @Override
                        public void onServiceResolved(NsdServiceInfo serviceInfo) {
                            // TODO Auto-generated method stub
                            Log.d(TAG, "Resolving service...");
                        }

                        @Override
                        public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode) {
                            // TODO Auto-generated method stub
                            Log.d(TAG, "Service resolve failed!");
                        }
                    });
                }
            }

            @Override
            public void onServiceLost(NsdServiceInfo service) {
                // When the network service is no longer available.
                // Internal bookkeeping code goes here.
                Log.e(TAG, "service lost: " + service);
            }

            @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);
            }
        };
    }
}

这个问题可以在所附的图片上看到（我不知道该怎么称呼它）。我经常犯错误。

有人能解释一下我做错了什么或者为什么我会犯这样的错误吗？我应该有不同的注册和发现端口吗(不同的NSD经理？）