android - 找不到处理 Intent { act=android.bluetooth.adapter.action.STATE_CHANGED } 的 Activity

Question

我正在编写此代码以了解如何在 Android 中使用蓝牙，但是我不断收到标题中提到的错误。完整错误是:java.lang.RuntimeException: 无法启动 Activity ComponentInfo{com.example.android/com.example.android.MainActivity}: android.content.ActivityNotFoundException: 找不到处理 Intent { act=android 的 Activity .bluetooth.adapter.action.STATE_CHANGED }

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest 
    xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android"
    android:versionCode="1"
    android:versionName="1.0">
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <application 
        android:label="@string/app_name" 
        android:icon="@drawable/ic_launcher">
        <receiver
            android:name=".MainActivity" >
            <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>

主要 Activity .java:

package com.example.android;

import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends Activity
{
    private final String LOG_TAG = getClass().getSimpleName();
    private static int REQUEST_ENABLE_BT = 1;
    private static int REQUEST_STATE_CHANGED_BT = 2;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        BluetoothAdapter oBTAdapter = BluetoothAdapter.getDefaultAdapter(); 
        if (oBTAdapter == null) Log.i(LOG_TAG, "This device does not support Bluetooth");
        if (!oBTAdapter.isEnabled()) {
            Intent iEnableBT = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
            startActivityForResult(iEnableBT, REQUEST_ENABLE_BT);           
        }
        Intent iBTStatus = new Intent(BluetoothAdapter.ACTION_STATE_CHANGED);
        startActivityForResult(iBTStatus, REQUEST_STATE_CHANGED_BT);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == REQUEST_ENABLE_BT) 
            if (resultCode == RESULT_CANCELED) Log.e(LOG_TAG, "Bluetooth was not enabled on the device");
        else if (requestCode == REQUEST_STATE_CHANGED_BT) 
            if (resultCode == RESULT_OK && !data.getStringExtra(BluetoothAdapter.EXTRA_STATE).equals(BluetoothAdapter.STATE_ON)) Log.e(LOG_TAG, "Bluetooth adapter is not on");   
    }    
}

在我打开蓝牙的设备上，通过日志我看到它确实跳过了 isEnabled() 测试(查看蓝牙当前是否已启用并可以使用)。它能够创建一个 Intent 来观察蓝牙状态，但它在 startActivityForResult() 上崩溃。我做错了什么？

Answer 1

您好，您没有任何此类事件处理 Activity ， 你应该尝试像这样制作 BroadcastReceiver

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:
            setButtonText("Bluetooth off");
            break;
        case BluetoothAdapter.STATE_TURNING_OFF:
            setButtonText("Turning Bluetooth off...");
            break;
        case BluetoothAdapter.STATE_ON:
            setButtonText("Bluetooth on");
            break;
        case BluetoothAdapter.STATE_TURNING_ON:
            setButtonText("Turning Bluetooth on...");
            break;
        }
    }
}
};

在你的 Activity 中这样做......

 IntentFilter filter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver(mReceiver, filter);