无法创建广播接收器android。

Question

我使用了安卓开发者指南提供的代码，以便创建广播接收器，但是我遇到了问题。

以下是代码：

    WifiP2pManager mManager;
    WifiP2pManager.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(mManager, mChannel, this);

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
}

它说找不到符号

WiFiDirectBroadcastReceiver

但是如果我尝试将 BroadcastReceiver mReceiver; 更改为 WiFiDirectBroadcastReceiver mReceiver;

就会出现错误，有什么想法吗？

- We're All Mad Here

Answer 1

WiFiDirectBroadcastReceiver是一个自定义类，你需要定义这个类，这也是为什么会显示错误的原因。

你忘记添加一个名为WiFiDirectBroadcastReceiver的类了。

因此，你的WiFiDirectBroadcastReceiver.java应该像这样：

public class WiFiDirectBroadcastReceiver extends BroadcastReceiver {

    private WifiP2pManager manager;
    private Channel channel;
    private WiFiDirectActivity activity;

    /**
     * @param manager WifiP2pManager system service
     * @param channel Wifi p2p channel
     * @param activity activity associated with the receiver
     */
    public WiFiDirectBroadcastReceiver(WifiP2pManager manager, Channel channel,
            WiFiDirectActivity activity) {
        super();
        this.manager = manager;
        this.channel = channel;
        this.activity = activity;
    }

    /*
     * (non-Javadoc)
     * @see android.content.BroadcastReceiver#onReceive(android.content.Context,
     * android.content.Intent)
     */
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {

            // UI update to indicate wifi p2p status.
            int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
            if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
                // Wifi Direct mode is enabled
                activity.setIsWifiP2pEnabled(true);
            } else {
                activity.setIsWifiP2pEnabled(false);
                activity.resetData();

            }
            Log.d(WiFiDirectActivity.TAG, "P2P state changed - " + state);
        } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {

            // 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 (manager != null) {
                manager.requestPeers(channel, (PeerListListener) activity.getFragmentManager()
                        .findFragmentById(R.id.frag_list));
            }
            Log.d(WiFiDirectActivity.TAG, "P2P peers changed");
        } else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {

            if (manager == 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

                DeviceDetailFragment fragment = (DeviceDetailFragment) activity
                        .getFragmentManager().findFragmentById(R.id.frag_detail);
                manager.requestConnectionInfo(channel, fragment);
            } else {
                // It's a disconnect
                activity.resetData();
            }
        } else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
            DeviceListFragment fragment = (DeviceListFragment) activity.getFragmentManager()
                    .findFragmentById(R.id.frag_list);
            fragment.updateThisDevice((WifiP2pDevice) intent.getParcelableExtra(
                    WifiP2pManager.EXTRA_WIFI_P2P_DEVICE));

        }
    }
}

原始文件可在GitHub或developer.android.com上找到。

- Lal