使用dispatchChange停止音量更改

Question

我正在尝试全局覆盖音量调高按钮，我已经设法使用下面的代码。问题是，当我这样做时，我不希望音量发生变化。我查看了内容观察器上的文档，发现了这种方法＆＃34; dispatchChange＆＃34;。我可以用它来取消音量变化吗？

package com.kuzoncode.pressed;

import android.content.Context;
import android.database.ContentObserver;
import android.media.AudioManager;
import android.nfc.Tag;
import android.util.Log;

import java.util.logging.Logger;

/**
 * Created by Bradley on 29/12/2014.
 */
public class SettingsContentObserver extends ContentObserver {
    private static final String TAG = "SettingContent";
    int previousVolume;
    Context context;

    public SettingsContentObserver(Context c, android.os.Handler handler) {
        super(handler);
        context = c;

        AudioManager audio = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
        previousVolume = audio.getStreamVolume(AudioManager.STREAM_MUSIC);
    }

    @Override
    public boolean deliverSelfNotifications() {
        return super.deliverSelfNotifications();
    }

    @Override
    public void onChange(boolean selfChange) {
        super.onChange(selfChange);

        AudioManager audio = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
        int currentVolume = audio.getStreamVolume(AudioManager.STREAM_MUSIC);
        //audio.setStreamVolume(AudioManager.STREAM_MUSIC, previousVolume, previousVolume);

        int delta = previousVolume - currentVolume;

        if (delta > 0) {
            Log.d(TAG, "Decreased");
            previousVolume = currentVolume;
        } else if (delta < 0) {
            Log.d(TAG, "Increased");
            previousVolume = currentVolume;
        }
    }
}