Question

所以我完成了我的作业并寻找类似的问题，实际上我找到了一个两年前遇到同样问题的人...... he didn't get any answer though.

问题如下：我正在从android做WifiP2p教程。我使用MainActivity上的discoverPeers()手动调用FloatingActionButton。然后在WifiDirectBroadcastReceiver类中广播并接收WIFI_P2P_PEERS_CHANGED_ACTION。我打电话给requestPeers()，如果至少有一个可发现的同伴，则会调用onPeersAvailable() （这非常有意义。）

然而问题是，一旦它发现了一个对等体，它将永远不会离开列表。即使我关闭检测到的设备。让我举一个例子来说明：

3台设备（A，B和C），均支持WiFi-Direct。
在设备A上启动应用程序，保持设备B和C关闭。
尝试用A检测，没有检测到任何内容。没问题。
转动打开设备B，转到WiFi-Direct设置，扫描。
尝试用A检测，检测B.没问题。
关闭关闭设备B.
尝试用A检测，没有检测到任何内容。没问题。
打开设备C，转到WiFi-Direct设置，扫描。
尝试使用A进行检测，检测C 和 B.但设备B仍然关闭。为什么它仍然被检测到？（最糟糕的是，它被检测到状态3，对应于AVAILABLE）

这种情况发生在设备的任何排列上。角色。所以问题实际上在代码中，因为它们都通过官方的WiFi-Direct设置窗口正常运行和检测。

这是我的MainActivity：

package com.gett.wifip2ptest;

import android.content.BroadcastReceiver;
import android.content.IntentFilter;
import android.net.wifi.p2p.WifiP2pDeviceList;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import android.content.Context;
import android.net.wifi.p2p.WifiP2pManager;
import android.net.wifi.p2p.WifiP2pManager.Channel;
import android.net.wifi.p2p.WifiP2pManager.PeerListListener;
import android.net.wifi.p2p.WifiP2pDevice;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements PeerListListener{

    private WifiP2pManager mManager;
    private Channel mChannel;
    private BroadcastReceiver mReceiver;

    private IntentFilter mIntentFilter;

    private List<WifiP2pDevice> peers = new ArrayList<WifiP2pDevice>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();

//                If the discovery process succeeds and detects peers, the system broadcasts the
//                WIFI_P2P_PEERS_CHANGED_ACTION intent.
                mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {
                    @Override
                    public void onSuccess() {
                        Toast.makeText(MainActivity.this, "Discovery Initiated",
                                Toast.LENGTH_SHORT).show();
                    }

                    @Override
                    public void onFailure(int reasonCode) {
                        Toast.makeText(MainActivity.this, "Discovery Failed : " + reasonCode,
                                Toast.LENGTH_SHORT).show();
                    }
                });
            }
        });

        mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
        mChannel = mManager.initialize(this, getMainLooper(), null);
        mReceiver = new WiFiDirectBroadcastReceiver(mManager, mChannel, this);

        mIntentFilter = new IntentFilter();
        mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
        mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
        mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
        mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
    }

    /* register the broadcast receiver with the intent values to be matched */
    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(mReceiver, mIntentFilter);
    }

    /* unregister the broadcast receiver */
    @Override
    protected void onPause() {
        super.onPause();
        unregisterReceiver(mReceiver);
    }

    @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);
    }

    /**
     * This function is called by requestPeers upon receiving the peers list.
     * @param peerList
     */
    @Override
    public void onPeersAvailable(WifiP2pDeviceList peerList) {
        peers.clear();
        System.out.println("Peers cleared : " + peers);

        peers.addAll(peerList.getDeviceList());

        System.out.println("Peers : " + peers);
        if (peers.size() == 0) {
            System.out.println("No devices found");
            return;
        }
    }
}

这是WiFiDirectBroadCastReceiver：

package com.gett.wifip2ptest;

import android.content.BroadcastReceiver;
import android.net.wifi.p2p.WifiP2pManager;
import android.net.wifi.p2p.WifiP2pManager.Channel;
import android.net.wifi.p2p.WifiP2pManager.PeerListListener;
import android.content.Context;
import android.content.Intent;

public class WiFiDirectBroadcastReceiver extends BroadcastReceiver {

    private WifiP2pManager mManager;
    private Channel mChannel;
    private MainActivity mActivity;

    public WiFiDirectBroadcastReceiver(WifiP2pManager manager, Channel channel,
                                       MainActivity activity) {
        super();
        this.mManager = manager;
        this.mChannel = channel;
        this.mActivity = activity;
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
            // Check to see if Wi-Fi is enabled and notify appropriate activity
            int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
            if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
                // Wifi P2P is enabled
                System.out.println("Wifi Direct has been enabled.");
            } else {
                // Wi-Fi P2P is not enabled
                System.out.println("Wifi Direct is NOT enabled.");
            }
        } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
            // Call WifiP2pManager.requestPeers() to get a list of current peers
            System.out.println("Peers changed.");

            // request available peers from the wifi p2p manager. This is an
            // asynchronous call and the calling activity is notified with a
            // callback on PeerListListener.onPeersAvailable()
            if (mManager != null) {
                mManager.requestPeers(mChannel, (PeerListListener) mActivity);
            }
        } else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
            // Respond to new connection or disconnections
        } else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
            // Respond to this device's wifi state changing
        }
    }
}

以下是其中一个被关闭时检测到两个对等体的示例：

02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out: Peers : [Device: Galaxy J1-2
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  deviceAddress: 2a:27:bf:3a:2e:55
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  primary type: 10-0050F204-5
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  secondary type: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  wps: 392
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  grpcapab: 0
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  devcapab: 37
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  status: 3
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  wfdInfo: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  groupownerAddress: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  GOdeviceName: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  interfaceAddress: 
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  SConnectInfo : null, Device: Test User (Galaxy J1)
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  deviceAddress: 2a:27:bf:3a:4a:8b
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  primary type: 10-0050F204-5
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  secondary type: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  wps: 392
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  grpcapab: 0
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  devcapab: 37
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  status: 3
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  wfdInfo: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  groupownerAddress: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  GOdeviceName: null
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  interfaceAddress: 
02-18 16:31:56.406 20833-20833/com.gett.wifip2ptest I/System.out:  SConnectInfo : null]

Answer 1

在WIFI_P2P_PEERS_CHANGED_ACTION

中尝试此操作

else if(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)){
            //Log.d("wifi", "WIFI PEERS CHANGED");
            mPeers = new ArrayList<WifiP2pDevice>();
            mConfigs = new ArrayList<WifiP2pConfig>();
            if(mManager != null){
                WifiP2pManager.PeerListListener peerListListener = new WifiP2pManager.PeerListListener(){
                    @Override
                    public void onPeersAvailable(WifiP2pDeviceList peerList) {
                        mPeers.clear();
                        mPeers.addAll(peerList.getDeviceList());
                        mActivity.displayPeers(peerList);
                        //mPeers.addAll(peerList.getDeviceList());
                        for(int i=0; i < peerList.getDeviceList().size(); i++){
                            WifiP2pConfig config = new WifiP2pConfig();
                            config.deviceAddress = mPeers.get(i).deviceAddress;
                            mConfigs.add(config);
                        }
                    }
                };
                mManager.requestPeers(mChannel, peerListListener);
            }
        }

MainActivity.java中的

displayPeers()

 public void displayPeers(WifiP2pDeviceList peerList){
        wifiP2pArrayAdapter.clear();
        for(WifiP2pDevice peer: peerList.getDeviceList()){
            wifiP2pArrayAdapter.add(peer.deviceName + "\n" + peer.deviceAddress);
        }
    }

Answer 2

发生这种情况是因为已关闭WiFi直连功能的设备不会向邻近设备发送任何不再可用的广播。

我尝试使用内置的WiFi Direct屏幕做同样的事情，并取得了与您相同的结果。从内置屏幕发现一些wifi p2p设备，然后在发现的设备中关闭wifi。它不会消失，直到系统再次调用discoverPeers（），该系统当前设置（在android框架中）在60秒后被调用。

因此，被禁用的设备将在60秒后消失。

这是正常的行为，可能你无能为力。

（相反，只要WiFi直接开启，设备就会发送广播说它在附近可用。这就是新设备立即出现的原因。）

Answer 3

我遇到了和你一样的问题，这是我的发现：

解释行为的好答案： https://stackoverflow.com/a/25154034/3260008

在我的代码中，我也测试了这个行为，与答案的说法相符，如果你打电话给discoverPeers()，60秒后，对等列表会被刷新。对我来说，这是可以接受的。

WifiP2pManager.requestPeers（）不断返回onPeersAvailable（）中的旧对等体

3 个答案: