如何使用BroadcastReceiver檢測藍牙狀態

我遇到了問題。我已閱讀此主題： How to detect Bluetooth state change using a broadcast receiver? 和我用相同的方式編寫我的應用程序，但是當我運行它並關閉應用程序的藍牙會崩潰。系統版本：4.0.3。下面是代碼：如何使用BroadcastReceiver檢測藍牙狀態

MainActivity：

package com.example.lokalizing; 
import android.app.Activity; 
import android.bluetooth.BluetoothAdapter; 
import android.bluetooth.BluetoothDevice; 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.content.IntentFilter; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.widget.Toast; 

public class MainActivity extends Activity { 

private final BroadcastReceiver mReceiver = new BroadcastReceiver() { 
    @Override 
    public void onReceive(Context context, Intent intent) { 
     final String action = intent.getAction(); 

     if (action.equals(BluetoothAdapter.ACTION_STATE_CHANGED)) { 
      final int state = intent.getIntExtra(BluetoothAdapter.EXTRA_STATE, 
               BluetoothAdapter.ERROR); 
      switch (state) { 
      case BluetoothAdapter.STATE_OFF: 
       Toast.makeText(context, "Bluetooth off", Toast.LENGTH_LONG); 
       break; 
      case BluetoothAdapter.STATE_TURNING_OFF: 
       Toast.makeText(context, "Turning Bluetooth off", Toast.LENGTH_LONG); 
       break; 
      case BluetoothAdapter.STATE_ON: 
       Toast.makeText(context, "Bluetooth on", Toast.LENGTH_LONG); 
       break; 
      case BluetoothAdapter.STATE_TURNING_ON: 
       Toast.makeText(context, "Turning Bluetooth on", Toast.LENGTH_LONG); 
       break; 
      } 
     } 
    } 
}; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    Toast.makeText(getApplicationContext(), "Włączono program", Toast.LENGTH_LONG).show(); 
    IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED); 
    registerReceiver(mReceiver, filter); 
} 

@Override 
public void onDestroy() { 
    super.onDestroy(); 

    /* ... */ 

    // Unregister broadcast listeners 
    unregisterReceiver(mReceiver); 
} 

public void showToast(String msg) { 
    Toast.makeText(getApplicationContext(),msg, Toast.LENGTH_SHORT).show(); 
} 
}

AndroidManifest：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
package="com.example.lokalizing" 
android:versionCode="1" 
android:versionName="1.0" > 

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

<uses-permission android:name="android.permission.BLUETOOTH" /> 

<application 
    android:allowBackup="true" 
    android:icon="@drawable/ic_launcher" 
    android:label="@string/app_name" 
    android:theme="@style/AppTheme" > 

    <receiver 
     android:name="com.example.lokalizing.MainActivity" 
     android:enabled="true"> 
     <intent-filter> 
      <action android:name="android.bluetooth.adapter.action.STATE_CHANGED"/> 
     </intent-filter> 
    </receiver> 

    <activity 
     android:name=".MainActivity" 
     android:label="@string/app_name" > 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 
      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 

</application> 

</manifest>

來源

2015-02-07 spajson

從你的清單中刪除<receiver>聲明。

您聲明MainActivity既是<activity>也是<receiver>。這是一個明確的禁忌。

當您在代碼中動態創建BroadcastReceiver並在onCreate()中註冊它時。你不需要在清單中有任何東西。

來源

2015-02-08 15:48:38

在Toast實現中，您錯過了調用方法show（）;

來源

2015-07-12 05:03:57

如何使用BroadcastReceiver檢測藍牙狀態

回答

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