Question

我正在开发一个Android应用程序，它应该能够识别出有人按下手机的硬件音量增加按钮，并发出通知说“按下音量按钮”。

这是我的BroadcastReceiver类。

package com.example.volumebut;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.view.KeyEvent;
import android.widget.Toast;

public class HardwareButtonReceiver extends BroadcastReceiver {



@Override
public void onReceive(Context context, Intent intent) {
 KeyEvent e = (KeyEvent) intent.getParcelableExtra(Intent.EXTRA_KEY_EVENT); 
     if(e.getKeyCode() == KeyEvent.KEYCODE_VOLUME_UP) {
        Toast.makeText(context, "volume up  button pressed." ,Toast.LENGTH_LONG).show();
     }

}





}

这是我的清单文件

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

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="18" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.volumebut.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>

    <receiver android:name=".HardwareButtonReceiver">
        <intent-filter>
            <action android:name="android.intent.action.MEDIA_BUTTON" />
        </intent-filter>
    </receiver>
</application>

</manifest>

由于我是Android开发的新手，我不知道如何实现 MainActivity.java 文件。

这是我到目前为止写的 MainActivity.java 文件。但它给出了一个错误，说明“方法registerMediaButtonEventReceiver（HardwareButtonReceiver）未定义类型MainActivity”

package com.example.volumebut;

import android.media.AudioManager;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.view.Menu;

public class MainActivity extends Activity {


public void onCreate(Bundle savedInstanceState) {

    HardwareButtonReceiver receiver = new HardwareButtonReceiver();

    registerMediaButtonEventReceiver(receiver);

}




}

如果你们能帮助我解决我的问题，我非常感激。

Answer 1

您必须将方法registerMediaButtonEventReceiver添加到您的活动类。

public class MainActivity extends Activity {
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.xml_of_your_activity);
        HardwareButtonReceiver receiver = new HardwareButtonReceiver();
        registerMediaButtonEventReceiver(receiver);
    }

    private void registerMediaButtonEventReceiver(HardwareButtonReceiver receiver) {

    }
}

然后实施它。

Answer 2

http://developer.android.com/reference/android/view/KeyEvent.html

通过上面的链接，您将获得不同的关键事件

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {


            if (keyCode == KeyEvent.KEYCODE_VOLUME_UP) {
//          
            }
            else if(keyCode == KeyEvent.KEYCODE_VOLUME_DOWN)
            {

            }

        return super.onKeyDown(keyCode, event);
    }

通过我的Android应用程序访问音量按钮

2 个答案: