使用Android Wi-Fi Direct API的问题:mChannel = mManager.initialize()

Question

这是我的第一篇文章,希望能做得对.我正在尝试使用新的Android技术Wi-Fi Direct创建一个应用程序.为此,我按照您可以找到的教程:

http://developer.android.com/guide/topics/connectivity/wifip2p.html

它真的很有用,但是当我复制代码时,有一些错误.正好与第3步:

WifiP2pManager mManager;
Channel mChannel;
BroadcastReceiver mReceiver;
...
@Override
protected void onCreate(Bundle savedInstanceState){
    ...
    mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
    mChannel = mManager.initialize(this, getMainLooper(), null);
    mReceiver = new WiFiDirectBroadcastReceiver(manager, channel, this);
    ...
}

错误在线:

mChannel = mManager.initialize(this, getMainLooper(), null);

并且错误消息是:

类型不匹配:无法从WifiPesManager.Channel转换为Channel

建议是做一个像这样的演员:

mChannel =(Channel)mManager.initialize(this,getMainLooper(),null);

但是当我为此更改代码时,运行应用程序时出现另一个错误:

10-25 12:08:34.845:E/AndroidRuntime(26634):java.lang.RuntimeException:无法启动活动ComponentInfo {android.nacho.WifiDirect/android.nacho.WifiDirect.WifiDirect}:java.lang.ClassCastException:android .net.wifi.p2p.WifiP2pManager $ Channel无法强制转换为java.nio.channels.Channel

只需添加其余的代码就是它在教程中的显示方式,但以防万一我要添加Activity和Broadcast类:

1主要活动:

    package android.nacho.WifiDirect;

import java.nio.channels.Channel;

import android.net.wifi.p2p.WifiP2pManager;
import android.os.Bundle;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.IntentFilter;
import android.view.Menu;

public class WifiDirect extends Activity {


    WifiP2pManager mManager;
    Channel mChannel;
    BroadcastReceiver mReceiver;

    IntentFilter mIntentFilter;

    @Override
    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_wifi_direct);


        //To register the BroadastReceiver
        mManager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
        mChannel =  (Channel) mManager.initialize(this, getMainLooper(), null); //It was necessary to make a cast (Channel)
        mReceiver = new WiFiBroadcastReceiver(mManager, mChannel, this, this);


        //To define the filter in the BroadcastReceiver
        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);


    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_wifi_direct, menu);
        return true;
    }

    //


    @Override
    protected void onResume() {
        super.onResume();
        registerReceiver(mReceiver, mIntentFilter);
    }

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

}

2-Broadcast类:

    package android.nacho.WifiDirect;

import java.nio.channels.Channel;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.wifi.p2p.WifiP2pManager;
import android.widget.Toast;



/**
 * A BroadcastReceiver that notifies of important Wi-Fi p2p events.
 */

public class WiFiBroadcastReceiver extends BroadcastReceiver {

    private WifiP2pManager manager;
    private Channel channel;
    private WifiDirect activity;
    //For toast, add also context
    private Context context;

    public WiFiBroadcastReceiver(WifiP2pManager manager, Channel channel, WifiDirect activity, Context context) {
        super();
        this.manager = manager;
        this.channel = channel;
        this.activity = activity;
        this.context= context;
    }

    @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) {

                Toast.makeText(context, "Wi-Fi Direct is enable", Toast.LENGTH_LONG).show();

             } else {

                Toast.makeText(context, "Wi-Fi Direct is not enable", Toast.LENGTH_LONG).show();
             }      

        } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
            // Call WifiP2pManager.requestPeers() to get a list of current peers
        } 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
        }
    }
}

3 Android Manifest:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="android.nacho.WifiDirect"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="14"
        android:targetSdkVersion="15" />

    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />




    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".WifiDirect"
            android:label="@string/title_activity_wifi_direct" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

非常感谢您的帮助!!!

Answer 1

您正在使用来自错误包的Channel类.

做 import android.net.wifi.p2p.WifiP2pManager.Channel;

代替

import java.nio.channels.Channel;