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() {

@Override
public void onSuccess() {
Log.d(TAG,"onSuccess");
}

@Override
public 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) {
mManager.requestPeers(mChannel, peerListListener);
}

下面为监听器中获取附近设备的代码：

private PeerListListener peerListListener = new PeerListListener() {
@Override
public void onPeersAvailable(WifiP2pDeviceList peerList) {

// Out with the old, in with the new.
peers.clear();
peers.addAll(peerList.getDeviceList());

// 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

@Override
public void connect() {
// Picking the first device found on the network.
WifiP2pDevice device = peers.get(0);

WifiP2pConfig config = new WifiP2pConfig();
config.deviceAddress = device.deviceAddress;
config.wps.setup = WpsInfo.PBC;

mManager.connect(mChannel, config, new ActionListener() {
@Override
public void onSuccess() {
// WiFiDirectBroadcastReceiver will notify us. Ignore for now.
}
@Override
public 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：mManager.requestConnectionInfo(mChannel, connectionListener);

if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {

if (mManager == null) {
return;
}

NetworkInfo networkInfo = (NetworkInfo) intent
.getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);

if (networkInfo.isConnected()) {

// We are connected with the other device, request connection
// info to find group owner IP

mManager.requestConnectionInfo(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;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.NetworkInfo;
import android.net.wifi.WpsInfo;
import android.net.wifi.p2p.WifiP2pConfig;
import android.net.wifi.p2p.WifiP2pDevice;
import android.net.wifi.p2p.WifiP2pDeviceList;
import android.net.wifi.p2p.WifiP2pInfo;
import android.net.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.net.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() {
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
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) {
mManager.requestPeers(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) intent
.getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);

if (networkInfo.isConnected()) {
mManager.requestConnectionInfo(mChannel, MainActivity.this);
}
} else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
Log.d(TAG,"WIFI_P2P_THIS_DEVICE_CHANGED_ACTION");
}
}
};

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(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() {
@Override
public void onClick(View v) {
int num = picker.getValue();
connect(num);
}
});
textView = (TextView) findViewById(R.id.text);
}

@Override
protected void onResume() {
super.onResume();
registerReceiver(mReceiver, intentFilter);
mManager.discoverPeers(mChannel, new WifiP2pManager.ActionListener() {

@Override
public void onSuccess() {
Log.d(TAG,"onSuccess");
}

@Override
public void onFailure(int reasonCode) {
Log.d(TAG,"onFailure");
}
});
}

@Override
protected void onPause() {
super.onPause();
unregisterReceiver(mReceiver);
}
private List<WifiP2pDevice> peers = new ArrayList<>();
private String[] peersName;
@Override
public void onPeersAvailable(WifiP2pDeviceList peerList) {
peers.clear();
peers.addAll(peerList.getDeviceList());
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 = peers.get(num);

WifiP2pConfig config = new WifiP2pConfig();
config.deviceAddress = device.deviceAddress;
config.wps.setup = WpsInfo.PBC;

mManager.connect(mChannel, config, new WifiP2pManager.ActionListener() {
@Override
public void onSuccess() {
Log.d(TAG,"connect sucess");
}

@Override
public void onFailure(int reason) {
Log.d(TAG,"connect fail");
}
});
}

@Override
public void onConnectionInfoAvailable(WifiP2pInfo info) {
textView.setVisibility(View.VISIBLE);
textView.setText("(connected)");
// InetAddress from WifiP2pInfo struct.
InetAddress groupOwnerAddress = info.groupOwnerAddress;
Log.d(TAG,"onConnectionInfoAvailable");
Log.d(TAG,info.toString());
if (info.groupFormed && info.isGroupOwner) {

} else if (info.groupFormed) {

}
}
}

布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/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 Direct Scaning..."
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button_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/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>

AndroidManifest.xml文件

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/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>

Color.xml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>