Android中使用NotificationCompat.MediaStyle导入

在Android开发中，通知栏是很重要的一部分。使用NotificationCompat库，我们可以在不同的Android版本间保持兼容性。而使用NotificationCompat.MediaStyle可以扩展通知栏的基本功能。下面是介绍如何使用NotificationCompat.MediaStyle。

步骤

1. 导入NotificationCompat.MediaStyle库

在build.gradle文件中添加以下代码：

dependencies {
    implementation 'com.android.support:support-media-compat:28.0.0'
}

2. 创建通知

NotificationCompat.Builder builder = new NotificationCompat.Builder(this, CHANNEL_ID)
        .setSmallIcon(R.drawable.notification_icon)
        .setContentTitle("Title")
        .setContentText("Content Text")
        .setPriority(NotificationCompat.PRIORITY_LOW)
        .setCategory(NotificationCompat.CATEGORY_MESSAGE)
        // add MediaStyle
        .setStyle(new MediaStyle()
                .setMediaSession(mediaSession.getSessionToken())
                .setShowActionsInCompactView(0,1 /* #1: pause button */, 2 /* #2: next button */)
                .setShowCancelButton(true)
                .setCancelButtonIntent(
                        MediaButtonReceiver.buildMediaButtonPendingIntent(
                                this, PlaybackStateCompat.ACTION_STOP)))
        .addAction(new NotificationCompat.Action(
                R.drawable.ic_previous, "Previous",
                MediaButtonReceiver.buildMediaButtonPendingIntent(
                        this, PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS)))
        .addAction(new NotificationCompat.Action(
                R.drawable.ic_pause, "Pause",
                MediaButtonReceiver.buildMediaButtonPendingIntent(
                        this, PlaybackStateCompat.ACTION_PAUSE)))
        .addAction(new NotificationCompat.Action(
                R.drawable.ic_next, "Next",
                MediaButtonReceiver.buildMediaButtonPendingIntent(
                        this, PlaybackStateCompat.ACTION_SKIP_TO_NEXT)))
        .setSubText("Sub Text");
NotificationManagerCompat.from(this).notify(NOTIFICATION_ID, builder.build());

3. 设置MediaStyle

.setStyle(new MediaStyle()
        .setMediaSession(mediaSession.getSessionToken())
        .setShowActionsInCompactView(0,1 /* #1: pause button */, 2 /* #2: next button */)
        .setShowCancelButton(true)
        .setCancelButtonIntent(
                MediaButtonReceiver.buildMediaButtonPendingIntent(
                        this, PlaybackStateCompat.ACTION_STOP)))

上述代码中，.setMediaSession()用于与MediaSessionCompat实例建立连接，并使通知栏与音频播放器同步；.setShowActionsInCompactView()用于指定在折叠视图中显示哪些动作；.setShowCancelButton()用于显示取消按钮；.setCancelButtonIntent()用于指定按下取消按钮后要执行的操作。

4. 添加动作按钮

.addAction(new NotificationCompat.Action(
        R.drawable.ic_previous, "Previous",
        MediaButtonReceiver.buildMediaButtonPendingIntent(
                this, PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS)))
.addAction(new NotificationCompat.Action(
        R.drawable.ic_pause, "Pause",
        MediaButtonReceiver.buildMediaButtonPendingIntent(
                this, PlaybackStateCompat.ACTION_PAUSE)))
.addAction(new NotificationCompat.Action(
        R.drawable.ic_next, "Next",
        MediaButtonReceiver.buildMediaButtonPendingIntent(
                this, PlaybackStateCompat.ACTION_SKIP_TO_NEXT)))

上述代码中，.addAction()用于添加动作按钮。使用MediaButtonReceiver.buildMediaButtonPendingIntent()链接到Action，该方法执行音频播放指令。

结语

上面介绍了如何使用NotificationCompat.MediaStyle扩展Android通知栏的功能。这里给出完整的代码示例。

import android.support.v4.media.app.NotificationCompat;
import android.support.v4.media.session.MediaButtonReceiver;
import android.support.v4.media.session.MediaSessionCompat;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.app.NotificationCompat;
import android.os.Bundle;
import android.widget.RemoteViews;

public class MainActivity extends AppCompatActivity {

    private static final String CHANNEL_ID = "channel_id";
    private static final int NOTIFICATION_ID = 0;

    private MediaSessionCompat mediaSession;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mediaSession = new MediaSessionCompat(this, TAG);
        mediaSession.setFlags(
                MediaSessionCompat.FLAG_HANDLES_MEDIA_BUTTONS |
                        MediaSessionCompat.FLAG_HANDLES_TRANSPORT_CONTROLS);
    }

    private void showNotification() {
        // create notification
        NotificationCompat.Builder builder = new NotificationCompat.Builder(this, CHANNEL_ID)
                .setSmallIcon(R.drawable.notification_icon)
                .setContentTitle("Title")
                .setContentText("Content Text")
                .setPriority(NotificationCompat.PRIORITY_LOW)
                .setCategory(NotificationCompat.CATEGORY_MESSAGE)
                // add MediaStyle
                .setStyle(new MediaStyle()
                        .setMediaSession(mediaSession.getSessionToken())
                        .setShowActionsInCompactView(0,1 /* #1: pause button */, 2 /* #2: next button */)
                        .setShowCancelButton(true)
                        .setCancelButtonIntent(
                                MediaButtonReceiver.buildMediaButtonPendingIntent(
                                        this, PlaybackStateCompat.ACTION_STOP)))
                .addAction(new NotificationCompat.Action(
                        R.drawable.ic_previous, "Previous",
                        MediaButtonReceiver.buildMediaButtonPendingIntent(
                                this, PlaybackStateCompat.ACTION_SKIP_TO_PREVIOUS)))
                .addAction(new NotificationCompat.Action(
                        R.drawable.ic_pause, "Pause",
                        MediaButtonReceiver.buildMediaButtonPendingIntent(
                                this, PlaybackStateCompat.ACTION_PAUSE)))
                .addAction(new NotificationCompat.Action(
                        R.drawable.ic_next, "Next",
                        MediaButtonReceiver.buildMediaButtonPendingIntent(
                                this, PlaybackStateCompat.ACTION_SKIP_TO_NEXT)))
                .setSubText("Sub Text");
        NotificationManagerCompat.from(this).notify(NOTIFICATION_ID, builder.build());
    }
}

以上即是使用NotificationCompat.MediaStyle扩展通知栏功能的完整教程。