我对Android很新，我正在开发一个直接通过WIFI交换数据的应用程序，我想使用DNS服务发现而不是纯粹的P2P发现来获取更多有用的信息，比如设备＆＃34;昵称＆＃34;等
到目前为止，我已经按照http://developer.android.com/training/connect-devices-wirelessly/index.html上的教程阅读了文档。
我的应用程序似乎成功注册了它的本地服务，并且始终调用来自discoverServices的onSuccess回调，但是从不接收来自其他设备的txtServiceRecord（我使用2个设备）。
这是我的完整代码：
package com.caballero.marco.dnssd_test;
import android.graphics.Color;
import android.net.wifi.p2p.WifiP2pDevice;
import android.net.wifi.p2p.WifiP2pManager;
import android.net.wifi.p2p.WifiP2pManager.Channel;
import android.net.wifi.p2p.WifiP2pManager.DnsSdTxtRecordListener;
import android.net.wifi.p2p.WifiP2pManager.DnsSdServiceResponseListener;
import android.net.wifi.p2p.nsd.WifiP2pDnsSdServiceInfo;
import android.net.wifi.p2p.WifiP2pManager.ActionListener;
import android.net.wifi.p2p.nsd.WifiP2pDnsSdServiceRequest;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.style.ForegroundColorSpan;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.TextView;
import java.io.IOException;
import java.net.ServerSocket;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
public class MainActivity extends ActionBarActivity
{
public static String SERVICE_NAME = "_marcotest";
private int server_port = 0;
private WifiP2pManager mManager;
private Channel channel;
private ServerSocket serverSocket;
private TextView txtServiceStatus;
private Button btnDiscover;
final HashMap<String, String> buddies = new HashMap<String, String>();
private ArrayAdapter<String> adapter;
//private ActionListener serviceDiscoveryListener;
private WifiP2pDnsSdServiceRequest serviceRequest;
private DnsSdServiceResponseListener serviceResponseListener;
private DnsSdTxtRecordListener txtRecordListener;
private WifiP2pDnsSdServiceInfo serviceInfo;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
/* Load controls */
txtServiceStatus = (TextView)findViewById(R.id.txtStatus);
btnDiscover = (Button)findViewById(R.id.btnDiscover);
btnDiscover.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startServiceDiscovery();
}
});
mManager = (WifiP2pManager)getSystemService(WIFI_P2P_SERVICE);
channel = mManager.initialize(this, getMainLooper(), null);
adapter = new ArrayAdapter<String>( this,
android.R.layout.simple_list_item_1,
new ArrayList<String>());
/* Initialize Socket Server */
try {
initializeSocketServer();
}
catch (IOException e)
{
e.printStackTrace();
}
startRegistration();
setupDiscoverServices();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
private void startRegistration() {
// Create a string map containing information about your service.
Map record = new HashMap();
record.put("listenport", String.valueOf(server_port));
record.put("buddyname", "John Doe" + (int) (Math.random() * 1000));
record.put("available", "visible");
// Service information. Pass it an instance name, service type
// _protocol._transportlayer , and the map containing
// information other devices will want once they connect to this one.
serviceInfo = WifiP2pDnsSdServiceInfo.newInstance(SERVICE_NAME, "._tcp", record);
// Add the local service, sending the service info, network channel,
// and listener that will be used to indicate success or failure of
// the request.
mManager.addLocalService(channel, serviceInfo, new WifiP2pManager.ActionListener() {
@Override
public void onSuccess() {
// Command successful! Code isn't necessarily needed here,
// Unless you want to update the UI or add logging statements.
SpannableString text = new SpannableString("Online");
text.setSpan(new ForegroundColorSpan(Color.GREEN), 0, text.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
txtServiceStatus.setText(text);
Log.v("DnsSDTest", "Service added.");
}
@Override
public void onFailure(int arg0)
{
// Command failed. Check for P2P_UNSUPPORTED, ERROR, or BUSY
SpannableString text = new SpannableString("Offline");
text.setSpan(new ForegroundColorSpan(Color.RED), 0, text.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
txtServiceStatus.setText(text);
}
});
}
private void initializeSocketServer() throws IOException
{
serverSocket = new ServerSocket(0);
server_port = serverSocket.getLocalPort();
}
private void setupDiscoverServices()
{
txtRecordListener = new WifiP2pManager.DnsSdTxtRecordListener() {
@Override
public void onDnsSdTxtRecordAvailable(String fullDomainName, Map<String, String> txtRecordMap, WifiP2pDevice srcDevice)
{
Log.v("DnsSDTest", "DnsSdTxtRecord available -" + txtRecordMap.toString());
buddies.put(srcDevice.deviceAddress, txtRecordMap.get("buddyname"));
}
};
serviceResponseListener = new DnsSdServiceResponseListener() {
@Override
public void onDnsSdServiceAvailable(String instanceName, String registrationType, WifiP2pDevice srcDevice)
{
// Update the device name with the human-friendly version from
// the DnsTxtRecord, assuming one arrived.
srcDevice.deviceName = buddies
.containsKey(srcDevice.deviceAddress) ? buddies
.get(srcDevice.deviceAddress) : srcDevice.deviceName;
// Add to the custom adapter defined specifically for showing
// wifi devices.
adapter.add(srcDevice.toString());
adapter.notifyDataSetChanged();
Log.v("DnsSDTest", "onBonjourServiceAvailable " + instanceName);
}
};
mManager.setDnsSdResponseListeners(channel, serviceResponseListener, txtRecordListener);
Log.v("DnsSDTest", "Added DNS SD response listeners.");
}
private void startServiceDiscovery()
{
serviceRequest = WifiP2pDnsSdServiceRequest.newInstance();
mManager.addServiceRequest(channel, serviceRequest, new ActionListener() {
@Override
public void onSuccess() {
Log.v("DnsSDTest", "Service Request added successfully!");
}
@Override
public void onFailure(int reason) {
Log.v("DnsSDTest", "Failed to add service request!");
}
});
mManager.discoverServices(channel, new ActionListener() {
@Override
public void onSuccess() {
Log.v("DnsSDTest", "Service discovery successfull!");
}
@Override
public void onFailure(int reason) {
Log.v("DnsSDTest", "Service discovery failed :(");
}
});
}
@Override
protected void onPause()
{
super.onPause();
mManager.removeLocalService(channel, serviceInfo, new ActionListener() {
@Override
public void onSuccess() {
Log.v("DnsSDTest", "Removed service");
serviceInfo = null;
}
@Override
public void onFailure(int reason) {
Log.v("DnsSDTest", "Failed to remove service");
}
});
}
@Override
protected void onResume()
{
super.onResume();
if(serviceInfo == null)
{
startRegistration();
}
}
@Override
protected void onDestroy()
{
super.onDestroy();
try {
if(!serverSocket.isClosed())
serverSocket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
答案 0 :(得分：4)
查找1：
只有在使用setupDiscoverServices()附加两个侦听器（服务侦听器和txtrecord侦听器）之后，才需要为这些附加的列表器创建服务请求并启动发现。您可以随时手动创建服务请求并使用按钮触发发现服务，这很容易出错。在使用按钮调用startServiceDiscovery()之前，无法保证听众实际上已连接。
解决方案1：在设置DNS SD响应侦听器之后，即在mManager.setDnsSdResponseListeners（）之后，尝试调用方法startServiceDiscovery（），而不是调用按钮单击Listener。
解决方案2：否则，我建议您移动
'mManager.addServiceRequest(channel, serviceRequest, new ActionListener() {....}'
部分加入'setupDiscoverServices()'方法并尝试激活startServiceDiscovery()的{{1}}中的按钮（'onSuccess()'）。通过这种方式，您可以实现连接侦听器，注册服务和启动发现（手动）之间的同步点
以下链接演示了WiFiDirect项目，其中对等体通过网络服务发现相互连接以进行消息交换。这种方法的顺序要求网络服务发现为我工作。 https://github.com/Hariharan-Gandhi/WiFriends/blob/master/app/src/main/java/tud/cnlab/wifriends/WiFriends.java
发现2： 我还注意到以下行中使用的服务类型是“.tcp”。
'mManager.addServiceRequest'但是，根据Android开发人员指南，第二个参数（服务类型）应采用以下格式：“_ protocol._transportlayer”。 http://developer.android.com/training/connect-devices-wirelessly/nsd.html。 在这里的演示代码developer.android.com/training/connect-devices-wirelessly/nsd-wifi-direct.html中，他们使用了“_presence._tcp”，其中“presence”是XMPP的消息传递协议。请参阅此处的详细说明Available service types in WifiP2pDnsSdServiceInfo.newInstance。
我不确定在SVR记录中省略服务名称是否可以接受 [知识渊博的任何人如果我错了，请更新我的身份]