Android移动开发-音量调节对话框的实现

Android手机上的需要音量调节有六大类铃音，分别是通话音、系统音、铃音、媒体音、闹钟音和通知音，不过音量键只有加大与减少两个键，当用户按音量增加键时，应用怎么知道用户希望加大那类铃音的音量呢？
要解决这个问题，最好是弹出一个对话框，让用户选择希望调节的铃音类型，并显示拖动条，方便用户把音量一次调整到位，不必连续按增加键或减少键。

• layout/dialog_volume.xml界面布局代码如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/transparent"
    android:gravity="center"
    android:orientation="vertical"
    android:paddingLeft="40dp"
    android:paddingRight="40dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/white"
        android:orientation="vertical">

        <SeekBar
            android:id="@+id/sb_music"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_margin="15dp"
            android:max="100"
            android:thumb="@drawable/seekbar_point" />
    </LinearLayout>

</LinearLayout>

• widget.VolumeDialog.java.java逻辑代码如下：

package com.fukaimei.keyevent.widget;

import android.app.Dialog;
import android.content.Context;
import android.media.AudioManager;
import android.os.Handler;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnKeyListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;

import com.fukaimei.keyevent.R;

public class VolumeDialog implements OnSeekBarChangeListener, OnKeyListener {
    private Dialog dialog;
    private View view;
    private SeekBar sb_music;
    private AudioManager mAudioMgr;
    private int MUSIC = AudioManager.STREAM_MUSIC;
    private int mMaxVolume;
    private int mNowVolume;

    public VolumeDialog(Context context) {
        mAudioMgr = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
        mMaxVolume = mAudioMgr.getStreamMaxVolume(MUSIC);
        mNowVolume = mAudioMgr.getStreamVolume(MUSIC);
        view = LayoutInflater.from(context).inflate(R.layout.dialog_volume, null);
        dialog = new Dialog(context, R.style.VolumeDialog);
        sb_music = (SeekBar) view.findViewById(R.id.sb_music);
        sb_music.setOnSeekBarChangeListener(this);
        sb_music.setProgress(sb_music.getMax() * mNowVolume / mMaxVolume);
    }

    public void show() {
        dialog.getWindow().setContentView(view);
        dialog.getWindow().setLayout(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
        dialog.show();
        sb_music.setFocusable(true);
        sb_music.setFocusableInTouchMode(true);
        sb_music.setOnKeyListener(this);
    }

    public void dismiss() {
        if (dialog != null && dialog.isShowing()) {
            dialog.dismiss();
        }
    }

    public boolean isShowing() {
        if (dialog != null) {
            return dialog.isShowing();
        } else {
            return false;
        }
    }

    public void adjustVolume(int direction, boolean fromActivity) {
        if (direction == AudioManager.ADJUST_RAISE) {
            mNowVolume += 1;
        } else {
            mNowVolume -= 1;
        }
        sb_music.setProgress(sb_music.getMax() * mNowVolume / mMaxVolume);
        mAudioMgr.adjustStreamVolume(MUSIC, direction, AudioManager.FLAG_PLAY_SOUND);
        if (mListener != null && fromActivity != true) {
            mListener.onVolumeAdjust(mNowVolume);
        }
        close();
    }

    private void close() {
        mHandler.removeCallbacks(mClose);
        mHandler.postDelayed(mClose, 2000);
    }

    private Handler mHandler = new Handler();
    private Runnable mClose = new Runnable() {
        @Override
        public void run() {
            dismiss();
        }
    };

    @Override
    public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
    }

    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
    }

    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
        mNowVolume = mMaxVolume * seekBar.getProgress() / seekBar.getMax();
        mAudioMgr.setStreamVolume(MUSIC, mNowVolume, AudioManager.FLAG_PLAY_SOUND);
        if (mListener != null) {
            mListener.onVolumeAdjust(mNowVolume);
        }
        close();
    }

    @Override
    public boolean onKey(View v, int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_VOLUME_UP && event.getAction() == KeyEvent.ACTION_DOWN) {
            adjustVolume(AudioManager.ADJUST_RAISE, false);
            return true;
        } else if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN && event.getAction() == KeyEvent.ACTION_DOWN) {
            adjustVolume(AudioManager.ADJUST_LOWER, false);
            return true;
        } else {
            return false;
        }
    }

    private VolumeAdjustListener mListener;

    public void setVolumeAdjustListener(VolumeAdjustListener listener) {
        mListener = listener;
    }

    public static interface VolumeAdjustListener {
        public abstract void onVolumeAdjust(int volume);
    }

}

• layout/activity_volume_set.xml界面布局代码如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:padding="5dp">

    <TextView
        android:id="@+id/tv_volume"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="按下加减键调整音乐音量"
        android:textColor="@color/black"
        android:textSize="17sp" />

</LinearLayout>

• VolumeSetActivity.java逻辑代码如下：

package com.fukaimei.keyevent;

import android.content.Context;
import android.media.AudioManager;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.KeyEvent;
import android.widget.TextView;

import com.fukaimei.keyevent.widget.VolumeDialog;

public class VolumeSetActivity extends AppCompatActivity implements VolumeDialog.VolumeAdjustListener {
    private TextView tv_volume;
    private VolumeDialog dialog;
    private AudioManager mAudioMgr;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_volume_set);
        tv_volume = (TextView) findViewById(R.id.tv_volume);
        mAudioMgr = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_VOLUME_UP && event.getAction() == KeyEvent.ACTION_DOWN) {
            showVolumeDialog(AudioManager.ADJUST_RAISE);
            return true;
        } else if (keyCode == KeyEvent.KEYCODE_VOLUME_DOWN && event.getAction() == KeyEvent.ACTION_DOWN) {
            showVolumeDialog(AudioManager.ADJUST_LOWER);
            return true;
        } else if (keyCode == KeyEvent.KEYCODE_BACK) {
            finish();
            return false;
        } else {
            return false;
        }
    }

    private void showVolumeDialog(int direction) {
        if (dialog == null || dialog.isShowing() != true) {
            dialog = new VolumeDialog(this);
            dialog.setVolumeAdjustListener(this);
            dialog.show();
        }
        dialog.adjustVolume(direction, true);
        onVolumeAdjust(mAudioMgr.getStreamVolume(AudioManager.STREAM_MUSIC));
    }

    @Override
    public void onVolumeAdjust(int volume) {
        tv_volume.setText("调节后的音乐音量大小为：" + volume);
    }

}

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