從Android 8.0（API 26）開(kāi)始，所有的Notification都要指定Channel（通道），對(duì)于每一個(gè)Channel你都可以單獨(dú)去設(shè)置它；比如通知開(kāi)關(guān)、提示音、是否震動(dòng)或者是重要程度等；這樣每個(gè)應(yīng)用程序的通知在用戶(hù)面前都是透明的。

下面我們來(lái)看一下通知的設(shè)置頁(yè)面和Channel的設(shè)置界面

Notification Setting

這邊通知設(shè)置界面中的類(lèi)別指的就是Channel，你必須要?jiǎng)?chuàng)建一個(gè)或者多個(gè)Channel；這邊需要注意的是如果你的tartgetSdkVersion>=26,如果你發(fā)布通知不指定Channel的話(huà)，通知是不會(huì)顯示的（系統(tǒng)會(huì)自動(dòng)記錄錯(cuò)誤）。

Channel Setting

創(chuàng)建Notification Channel

1. 創(chuàng)建NotificationChannel對(duì)象，指定Channel的id、name和通知的重要程度。

2. setDescription可以指定設(shè)置中Channel的描述，如上圖中的（this is default channel!）

3. 使用NotificationMannager的createNotificationChannel方法來(lái)添加Channel。

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
{
    mNotificationChannel = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME, NotificationManager.IMPORTANCE_DEFAULT);
    mNotificationChannel.setDescription(CHANNEL_DESCRIPTION);
    getNotificationManager().createNotificationChannel(mNotificationChannel);
}

設(shè)置通知重要性級(jí)別

該級(jí)別必須要在NotificationChannel的構(gòu)造函數(shù)中指定，總共要五個(gè)級(jí)別；范圍是從 NotificationManager.IMPORTANCE_NONE(0) ~ NotificationManager.IMPORTANCE_HIGH(4)
，如果要支持Android 7.1（API 25）及以下的設(shè)備，還得調(diào)用NotificationCompat的setPriority方法來(lái)設(shè)置，如下所示

builder.setPriority(NotificationCompat.PRIORITY_DEFAULT);

我們總結(jié)一下；Android 8.0及以上是使用NotificationManager.IMPORTANCE_*，Android 7.1及以下是使用NotificationCompat.PRIORITY_*它們都是定義的常量；下面我們以表格的形式更好的展示出來(lái)。

對(duì)于上面這些通知級(jí)別用戶(hù)都是可以在Channel設(shè)置中更改的，嗯就是這樣！

打開(kāi)Channel設(shè)置

為了讓用戶(hù)能夠輕松訪(fǎng)問(wèn)Channel設(shè)置，我們可以通過(guò)下面的代碼在APP中加入設(shè)置入口點(diǎn)，這樣用戶(hù)體驗(yàn)可能會(huì)更好！

public void openChannelSetting(String channelId)
{
    Intent intent = new Intent(Settings.ACTION_CHANNEL_NOTIFICATION_SETTINGS);
    intent.putExtra(Settings.EXTRA_APP_PACKAGE, getPackageName());
    intent.putExtra(Settings.EXTRA_CHANNEL_ID, channelId);
    if (getPackageManager().resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY) != null)
        startActivity(intent);
}

打開(kāi)通知設(shè)置

public void openNotificationSetting()
{
    Intent intent = new Intent(Settings.ACTION_APP_NOTIFICATION_SETTINGS);
    intent.putExtra(Settings.EXTRA_APP_PACKAGE, getPackageName());
    if (getPackageManager().resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY) != null)
        startActivity(intent);
}

最后貼一下封裝的代碼（封裝的不是很好）

/**
 * @author xuyj
 */
public class NotificationHelper extends ContextWrapper
{
    private NotificationManager mNotificationManager;
    private NotificationChannel mNotificationChannel;

    public static final  String CHANNEL_ID          = "default";
    private static final String CHANNEL_NAME        = "Default Channel";
    private static final String CHANNEL_DESCRIPTION = "this is default channel!";

    public NotificationHelper(Context base)
    {
        super(base);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
        {
            mNotificationChannel = new NotificationChannel(CHANNEL_ID, CHANNEL_NAME, NotificationManager.IMPORTANCE_DEFAULT);
            mNotificationChannel.setDescription(CHANNEL_DESCRIPTION);
            getNotificationManager().createNotificationChannel(mNotificationChannel);
        }
    }

    public NotificationCompat.Builder getNotification(String title, String content)
    {
        NotificationCompat.Builder builder = null;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O)
        {
            builder = new NotificationCompat.Builder(this, CHANNEL_ID);
        } else
        {
            builder = new NotificationCompat.Builder(this);
            builder.setPriority(NotificationCompat.PRIORITY_DEFAULT);
        }
        builder.setContentTitle(title);
        builder.setContentText(content);
        builder.setSmallIcon(R.mipmap.comments);
        builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.comments));
        //點(diǎn)擊自動(dòng)刪除通知
        builder.setAutoCancel(true);
        return builder;
    }

    public void notify(int id, NotificationCompat.Builder builder)
    {
        if (getNotificationManager() != null)
        {
            getNotificationManager().notify(id, builder.build());
        }
    }

    public void openChannelSetting(String channelId)
    {
        Intent intent = new Intent(Settings.ACTION_CHANNEL_NOTIFICATION_SETTINGS);
        intent.putExtra(Settings.EXTRA_APP_PACKAGE, getPackageName());
        intent.putExtra(Settings.EXTRA_CHANNEL_ID, channelId);
        if (getPackageManager().resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY) != null)
            startActivity(intent);
    }

    public void openNotificationSetting()
    {
        Intent intent = new Intent(Settings.ACTION_APP_NOTIFICATION_SETTINGS);
        intent.putExtra(Settings.EXTRA_APP_PACKAGE, getPackageName());
        if (getPackageManager().resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY) != null)
            startActivity(intent);
    }

    private NotificationManager getNotificationManager()
    {
        if (mNotificationManager == null)
            mNotificationManager = (NotificationManager) this.getSystemService(this.NOTIFICATION_SERVICE);
        return mNotificationManager;
    }

}

Demo點(diǎn)這里

參考

https://developer.android.google.cn/training/notify-user/channels.html
https://github.com/googlesamples/android-NotificationChannels/#readme