安卓开发音乐盒设计

音乐盒设计

1.1 环境配置

  • Android Studio 4.1.2
  • Gradle 6.5
  • JDK 12
  • Android 7.0

1.2 需求描述

1、掌握BroadCast广播机制的使用

2、使用广播进行歌曲的播放暂停、上一首、下一首功能。

1.3 演示效果

效果

二、操作步骤

2.1 设计界面

image-20210506105245470

然后准备歌曲，放置在assets文件夹下，供AssetFileDescriptor进行读取。

2.2 编写Service和Activity

Service的onCreate()中需要创建一个BroadcastReceiver和创建IntentFilter，在代码里进行动态绑定。另外也可以选择在AndroidManifest.xml中进行静态绑定，但是静态绑定优先级会低于动态绑定。然后开启线程以发送广播的方式传递消息。

我们还需要添加一个监听器mPlayer.setOnCompletionListener()监听音乐是否已经播放完成，如果完成则自动切换到下一首。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
@Override
public void onCreate() {
    super.onCreate();
    am = getAssets();


    serviceReceiver = new MyReceiver();

    IntentFilter filter = new IntentFilter();
    filter.addAction(MainActivity.CTL_ACTION);
    registerReceiver(serviceReceiver, filter);


    // 创建MediaPlayer
    mPlayer = new MediaPlayer();

    mPlayer.setOnCompletionListener(mp -> {
        Log.d("musicService", "播放完成");
        current++;
        if (current >= 3) {
            current = 0;
        }

        prepareAndPlay(musics[current]);
        //发送广播通知Activity更改文本框
        Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);
        sendIntent.putExtra("current", current);
        sendIntent.putExtra("currentTime", mPlayer.getCurrentPosition());
        sendIntent.putExtra("totalTime", mPlayer.getDuration());
        // 发送广播
        sendBroadcast(sendIntent);

    });
    Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);
    sendIntent.putExtra("current", current);
    // 发送广播
    sendBroadcast(sendIntent);

    // 刷新进度条
    processThread = new Thread(() -> {
        while (true) {
            if (status == 0x12) {
                try {
                    Thread.sleep(1000);
                    Intent sendIntent1 = new Intent(MainActivity.UPDATE_ACTION);
                    sendIntent1.putExtra("current", current);
                    sendIntent1.putExtra("currentTime", mPlayer.getCurrentPosition());
                    sendIntent1.putExtra("totalTime", mPlayer.getDuration());
                    // 发送广播
                    sendBroadcast(sendIntent1);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    });
    processThread.start();
}

Service中还需要添加一个Receiver进行广播消息的接收处理。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
public class MyReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(final Context context, Intent intent) {
        int control = intent.getIntExtra("control", -1);
        Log.d("musicReceiver", "收到广播, control=" + control);
        switch (control) {
            // 播放或暂停
            case 1:
                // 原来处于没有播放状态
                if (status == 0x11) {
                    // 准备并播放音乐
                    prepareAndPlay(musics[current]);
                    status = 0x12;
                }
                // 原来处于播放状态
                else if (status == 0x12) {
                    // 暂停
                    mPlayer.pause();
                    // 改变为暂停状态
                    status = 0x13;
                }
                // 原来处于暂停状态
                else if (status == 0x13) {
                    // 播放
                    mPlayer.start();
                    // 改变状态
                    status = 0x12;
                }
                break;
                // 下一首
            case 2:
                if (status == 0x12 || status == 0x13) {
                    mPlayer.stop();
                    if (current + 1 >= musics.length) {
                        current = 0;
                    } else {
                        current++;
                    }
                    prepareAndPlay(musics[current]);
                    status = 0x12;
                    break;
                }
                // 上一首
            case 3:
                if (status == 0x12 || status == 0x13) {
                    mPlayer.stop();
                    if (current - 1 < 0) {
                        current = musics.length - 1;
                    } else {
                        current--;
                    }
                    prepareAndPlay(musics[current]);
                    status = 0x12;
                }

        }

        // 广播通知Activity更改图标、文本框
        Intent sendIntent = new Intent(MainActivity.UPDATE_ACTION);
        sendIntent.putExtra("update", status);
        sendIntent.putExtra("current", current);
        // 发送广播，将被Activity组件中的BroadcastReceiver接收到
        sendBroadcast(sendIntent);
    }
}

在MainActivity中，我们也需要创建一个BroadcastReceiver来接收Service传递的广播并进行处理。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
public class ActivityReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        // 获取Intent中的update消息，update代表播放状态
        int update = intent.getIntExtra("update", -1);
        // 获取Intent中的current消息，current代表当前正在播放的歌曲
        int current = intent.getIntExtra("current", -1);
        int totalPosition = intent.getIntExtra("totalTime", -1);
        int currentPosition = intent.getIntExtra("currentTime", -1);
        Log.d("activityReceiver", "收到广播");
        Log.d("activityReceiver", "current:" + current + " totalPosition:" + totalPosition + " currentPosition:" + currentPosition + " update:" + update);
        if (current >= 0) {
            title.setText(titleStrs[current]);
            author.setText(authorStrs[current]);
        }

        if (totalPosition >= 0) {
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("mm:ss", Locale.CHINA);
            Date date = new Date(totalPosition);
            String formatTime = simpleDateFormat.format(date);
            totalTime.setText(formatTime);
        }

        if (currentPosition >= 0) {
            double process = ((double)currentPosition / totalPosition)*100;
            Log.d("activityReceiver", "当前进度:" + (double)currentPosition/totalPosition);
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("mm:ss", Locale.CHINA);
            Date date = new Date(currentPosition);
            String formatTime = simpleDateFormat.format(date);
            progressBar.setProgress((int) process);
            currentTime.setText(formatTime);
        }

        switch (update) {
            case 0x11:
                play.setImageResource(R.drawable.play);
                status = 0x11;
                break;
            // 控制系统进入播放状态
            case 0x12:
                play.setImageResource(R.drawable.pause);
                status = 0x12;
                break;
            // 控制系统进入暂停状态
            case 0x13:
                play.setImageResource(R.drawable.play);
                status = 0x13;
                break;
        }
    }
}

最后是Activity中监听点击事件，每次点击事件都会发送广播。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
@Override
public void onClick(View source) {
    // 创建Intent
    Intent intent = new Intent("org.xr.action.CTL_ACTION");
    switch (source.getId()) {
        // 按下播放/暂停按钮
        case R.id.play:
            intent.putExtra("control", 1);
            break;
        case R.id.lastMusic:
            intent.putExtra("control", 3);
        case R.id.nextMusic:
            intent.putExtra("control", 2);
    }
    // 发送广播，将被Service组件中的BroadcastReceiver接收到
    sendBroadcast(intent);
}

核心功能到此就基本介绍完毕。

项目代码地址：https://gitee.com/retain990/musicbox