Android wifi探究三：Wifi P2P 连接附近设备

Android wifi探究三：Wifi P2P 连接附近设备

Wi-Fi Direct APIs允许应用连接周围的设备，而不用通过网络或者热点，点对点直接连接。应用可以快速的发现周围设备并与之交互，而有效作用距离大于蓝牙。这篇博客对如何实现Wi-Fi P2P设备间的连接做一个总结，如有不对之处，欢迎拍砖。下图是这篇博客所要展示的内容：

打开应用后，应用程序开始查找附近的可连接设备，并把结果显示在一个NumberPicker中，我们可以选择一个设备，然后点击CONNECT按钮，就可以连接到附近的设备。

Wi-Fi P2P连接过程总结

1.权限

首先我们需要这三个权限。

<uses-permission
        android:required="true"android:name="android.permission.ACCESS_WIFI_STATE"/><uses-permission
        android:required="true"android:name="android.permission.CHANGE_WIFI_STATE"/><uses-permission
        android:required="true"android:name="android.permission.INTERNET"/>

2.注册广播接收器

我们需要如下四个广播：
WIFI_P2P_STATE_CHANGED_ACTION
Indicates whether Wi-Fi P2P is enabled
—- 表明Wi-Fi P2P有没有使能
WIFI_P2P_PEERS_CHANGED_ACTION
Indicates that the available peer list has changed.
—- 表明可用的peer list发生了改变
WIFI_P2P_CONNECTION_CHANGED_ACTION
Indicates the state of Wi-Fi P2P connectivity has changed.
—- 表明Wi-Fi P2P连接状态发生了改变
WIFI_P2P_THIS_DEVICE_CHANGED_ACTION
Indicates this device’s configuration details have changed.
—-表明这个设备的配置信息发生了改变

3.初始化

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

initialize方法返回一个WifiP2pManager.Channel的实例，标示一个 通道，以后我们就要使用这个通道来查找和连接Wi-Fi P2P设备。

4.开始查找附近设备

 mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {@Overridepublic void onSuccess() {Log.d(TAG,"onSuccess");}@Overridepublic void onFailure(int reasonCode) {Log.d(TAG,"onFailure");}});

discoverPeers方法发起查找，这个查找是异步的，查找结束后回调方法会被调用，从而使我们可以得知查找成功还是失败。

5.获取设备列表

discoverPeers发起查找以后，一旦查找到附近设备，WIFI_P2P_PEERS_CHANGED_ACTION广播就会触发，我们可以在该广播中调用requestPeers方法来请求过去设备列表。
requestPeers需要两个参数，第一个就是我们的通道，由mManager.initialize方法返回，第二个参数是一个监听器。发送获取设备列表请求后，监听器中的方法onPeersAvailable就会被调用，我们可以在其中获取到附近的设备。
下面为请求获取设备列表的代码：

        if (mManager != null) {questPeers(mChannel, peerListListener);}

下面为监听器中获取附近设备的代码：

    private PeerListListener peerListListener = new PeerListListener() {@Overridepublic void onPeersAvailable(WifiP2pDeviceList peerList) {// Out with the old, in with the new.peers.clear();peers.DeviceList());// If an AdapterView is backed by this data, notify it// of the change.  For instance, if you have a ListView of available// peers, trigger an update.((WiFiPeerListAdapter) getListAdapter()).notifyDataSetChanged();if (peers.size() == 0) {Log.d(WiFiDirectActivity.TAG, "No devices found");return;}}}

6.连接到设备

 @Overridepublic void connect() {// Picking the first device found on the network.WifiP2pDevice device = (0);WifiP2pConfig config = new WifiP2pConfig();config.deviceAddress = device.deviceAddress;config.wps.setup = WpsInfo.t(mChannel, config, new ActionListener() {@Overridepublic void onSuccess() {// WiFiDirectBroadcastReceiver will notify us. Ignore for now.}@Overridepublic void onFailure(int reason) {}});}

连接成功后，我们就会收到WIFI_P2P_CONNECTION_CHANGED_ACTION广播，我们可以在广播中请求过去更加详细的信息，使用的方法是&#questConnectionInfo(mChannel, connectionListener);

if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {if (mManager == null) {return;}NetworkInfo networkInfo = (NetworkInfo) ParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);if (networkInfo.isConnected()) {// We are connected with the other device, request connection// info to find group questConnectionInfo(mChannel, connectionListener);}

requestConnectionInfo方法的第二个参数也是一个监听器，请求过去详细信息以后，这个监听器的onConnectionInfoAvailable方法就会被调用，我们可以在其中获取谁是“群主”等信息。

实例

以上为连接一个Wi-Fi P2P设备的步骤，下面博客一开始展示的应用程序的代码，供大家参考：

MainActivity.java

package com.jinwei.wifip2ptest;import android.app.Activity;
t.BroadcastReceiver;
t.Context;
t.Intent;
t.IntentFilter;
import android.NetworkInfo;
import android.wifi.WpsInfo;
import android.wifi.p2p.WifiP2pConfig;
import android.wifi.p2p.WifiP2pDevice;
import android.wifi.p2p.WifiP2pDeviceList;
import android.wifi.p2p.WifiP2pInfo;
import android.wifi.p2p.WifiP2pManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.NumberPicker;
import android.widget.TextView;
import android.widget.Toast;import java.InetAddress;
import java.util.ArrayList;
import java.util.List;public class MainActivity extends Activity implements  WifiP2pManager.PeerListListener,WifiP2pManager.ConnectionInfoListener{private final IntentFilter intentFilter = new IntentFilter();WifiP2pManager.Channel mChannel;WifiP2pManager mManager;NumberPicker picker;Button button;TextView textView;private final String TAG = "MainActivity";private final BroadcastReceiver mReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {String action = Action();if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {Log.d(TAG,"WIFI_P2P_STATE_CHANGED_ACTION");} else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {Log.d(TAG,"WIFI_P2P_PEERS_CHANGED_ACTION");if (mManager != null) {questPeers(mChannel, MainActivity.this);}Log.d(TAG, "P2P peers changed");} else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {Log.d(TAG,"WIFI_P2P_CONNECTION_CHANGED_ACTION");if (mManager == null) {return;}NetworkInfo networkInfo = (NetworkInfo) ParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);if (networkInfo.isConnected()) {questConnectionInfo(mChannel, MainActivity.this);}} else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {Log.d(TAG,"WIFI_P2P_THIS_DEVICE_CHANGED_ACTION");}}};@Overrideprotected void onCreate(Bundle savedInstanceState) {Create(savedInstanceState);setContentView(R.layout.activity_main);intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);mChannel = mManager.initialize(this, getMainLooper(), null);picker = (NumberPicker) findViewById(R.id.pick);picker.setDescendantFocusability(NumberPicker.FOCUS_BLOCK_DESCENDANTS);peersName = new String[1];peersName[0]="No Devices";picker.setDisplayedValues(peersName);button = (Button) findViewById(R.id.button);button.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {int num = Value();connect(num);}});textView = (TextView) findViewById();}@Overrideprotected void onResume() {Resume();registerReceiver(mReceiver, intentFilter);mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {@Overridepublic void onSuccess() {Log.d(TAG,"onSuccess");}@Overridepublic void onFailure(int reasonCode) {Log.d(TAG,"onFailure");}});}@Overrideprotected void onPause() {Pause();unregisterReceiver(mReceiver);}private List<WifiP2pDevice> peers = new ArrayList<>();private String[] peersName;@Overridepublic void onPeersAvailable(WifiP2pDeviceList peerList) {peers.clear();peers.DeviceList());if (peers.size() == 0) {Log.d(TAG, "No devices found");textView.setVisibility(View.INVISIBLE);if (peersName.length>0){peersName[0]="No Devices";}else {peersName = new String[1];peersName[0]="No Devices";}return;}else{peersName = new String[peers.size()];int i=0;for(WifiP2pDevice device: peers){peersName[i++]=device.deviceName;}textView.setVisibility(View.VISIBLE);textView.setText("(avaliable)");}picker.setDisplayedValues(peersName);}public void connect(final int num) {// Picking the first device found on the network.WifiP2pDevice device = (num);WifiP2pConfig config = new WifiP2pConfig();config.deviceAddress = device.deviceAddress;config.wps.setup = WpsInfo.t(mChannel, config, new WifiP2pManager.ActionListener() {@Overridepublic void onSuccess() {Log.d(TAG,"connect sucess");}@Overridepublic void onFailure(int reason) {Log.d(TAG,"connect fail");}});}@Overridepublic void onConnectionInfoAvailable(WifiP2pInfo info) {textView.setVisibility(View.VISIBLE);textView.setText("(connected)");// InetAddress from WifiP2pInfo struct.InetAddress groupOwnerAddress = upOwnerAddress;Log.d(TAG,"onConnectionInfoAvailable");Log.d(String());if (upFormed && info.isGroupOwner) {} else if (upFormed) {}}
}

布局文件l

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android=""xmlns:tools=""android:layout_width="match_parent"android:layout_height="match_parent"android:paddingBottom="@dimen/activity_vertical_margin"android:paddingLeft="@dimen/activity_horizontal_margin"android:paddingRight="@dimen/activity_horizontal_margin"android:paddingTop="@dimen/activity_vertical_margin"tools:context="com.jinwei.wifip2ptest.MainActivity"><TextView
        android:text="Wi-Fi "android:layout_centerHorizontal="true"android:layout_width="wrap_content"android:layout_height="wrap_content" /><NumberPicker
        android:layout_centerInParent="true"android:id="@+id/pick"android:focusableInTouchMode="true"android:focusable="true"android:layout_width="200dp"android:layout_height="200dp"></NumberPicker><TextView
        android:text="helllo"android:layout_toRightOf="@+id/pick"android:id="@+id/text"android:visibility="invisible"android:layout_centerVertical="true"android:layout_width="wrap_content"android:layout_height="wrap_content" /><Button
        android:id="@+id/button"android:text="connect"android:background="@drawable/button_bg"android:layout_below="@+id/pick"android:layout_marginStart="700dp"android:layout_width="wrap_content"android:layout_height="wrap_content" />
</RelativeLayout>

按钮的背景文件l

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="" ><item  android:state_focused="true"><shape android:shape="rectangle"><corners android:bottomLeftRadius="5dip" android:bottomRightRadius="5dip" android:topLeftRadius="5dip" android:topRightRadius="5dip" /><solid android:color="@color/button_focus"/></shape></item><item android:state_focused="false"><shape android:shape="rectangle"><corners android:bottomLeftRadius="5dip" android:bottomRightRadius="5dip" android:topLeftRadius="5dip" android:topRightRadius="5dip" /><solid android:color="@color/button_color"/></shape></item><item android:state_selected="true"><shape android:shape="rectangle"><corners android:bottomLeftRadius="5dip" android:bottomRightRadius="5dip" android:topLeftRadius="5dip" android:topRightRadius="5dip" /><solid android:color="@color/button_focus"/></shape></item><item  android:state_selected="false"><shape android:shape="rectangle"><corners android:bottomLeftRadius="5dip" android:bottomRightRadius="5dip" android:topLeftRadius="5dip" android:topRightRadius="5dip" /><solid android:color="@color/button_color"/></shape></item>   </selector>

l文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android=""package="com.jinwei.wifip2ptest"><uses-permission
        android:required="true"android:name="android.permission.ACCESS_WIFI_STATE"/><uses-permission
        android:required="true"android:name="android.permission.CHANGE_WIFI_STATE"/><uses-permission
        android:required="true"android:name="android.permission.INTERNET"/><application
        android:allowBackup="true"android:icon="@mipmap/ic_launcher"android:label="@string/app_name"android:supportsRtl="true"><activity android:name=".MainActivity"><intent-filter><action android:name="android.intent.action.MAIN" /><category android:name="android.intent.category.LAUNCHER" /></intent-filter></activity></application></manifest>

l文件

<?xml version="1.0" encoding="utf-8"?>
<resources><color name="colorPrimary">#3F51B5</color><color name="colorPrimaryDark">#303F9F</color><color name="colorAccent">#FF4081</color><color name="button_color">#ff546f7a</color><color name="button_focus">#ff0277bd</color>
</resources>