如何在 Android 应用中显示通知数量?
androidapps/applicationsmobile development
此示例演示了如何在 Android 应用启动器中显示通知数量。
步骤 1 − 在 Android Studio 中创建一个新项目，前往"文件"->"新建项目"，并填写所有必填信息以创建新项目。
步骤 2 − 将以下代码添加到 res/layout/activity_main.xml。
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:padding = "16dp" tools:context=".MainActivity"> <Button android:onClick = "createNotification" android:text = "create notification" android:layout_centerInParent = "true" android:layout_width = "match_parent" android:layout_height = "wrap_content" /> </RelativeLayout>
步骤 3 − 将以下代码添加到 src/MainActivity.java
package com.app.sample;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.app.NotificationChannel ;
import android.app.NotificationManager ;
import android.app.PendingIntent ;
import android.content.Intent ;
import android.os.Bundle ;
import android.view.View ;
import static android.app.Notification. BADGE_ICON_SMALL ;
public class MainActivity extends AppCompatActivity {
static int count = 0 ;
public static final String NOTIFICATION_CHANNEL_ID = "10001" ;
private final static String default_notification_channel_id = "default" ;
@Override
protected void onResume () {
super .onResume() ;
count = 0 ;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@SuppressLint("WrongConstant")
public void createNotification (View view) {
count ++ ;
Intent notificationIntent = new Intent(getApplicationContext() , MainActivity.class ) ;
notificationIntent.putExtra( "fromNotification" , true ) ;
notificationIntent.setFlags(Intent. FLAG_ACTIVITY_CLEAR_TOP | Intent. FLAG_ACTIVITY_SINGLE_TOP ) ;
PendingIntent pendingIntent = PendingIntent. getActivity ( this, 0 , notificationIntent , 0 ) ;
NotificationManager mNotificationManager = (NotificationManager) getSystemService( NOTIFICATION_SERVICE ) ;
NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(getApplicationContext() , default_notification_channel_id ) ;
mBuilder.setContentTitle( "My Notification" ) ;
mBuilder.setContentIntent(pendingIntent) ;
mBuilder.setContentText( "Notification Listener Service Example" ) ;
mBuilder.setSmallIcon(R.drawable. ic_launcher_foreground ) ;
mBuilder.setAutoCancel( true ) ;
mBuilder.setBadgeIconType( BADGE_ICON_SMALL ) ;
mBuilder.setNumber( count ) ;
if (android.os.Build.VERSION. SDK_INT >= android.os.Build.VERSION_CODES. O ) {
int importance = NotificationManager. IMPORTANCE_HIGH ;
NotificationChannel notificationChannel = new NotificationChannel( NOTIFICATION_CHANNEL_ID , "NOTIFICATION_CHANNEL_NAME" , importance) ;
mBuilder.setChannelId( NOTIFICATION_CHANNEL_ID ) ;
assert mNotificationManager != null;
mNotificationManager.createNotificationChannel(notificationChannel) ;
}
assert mNotificationManager != null;
mNotificationManager.notify(( int ) System. currentTimeMillis () ,
mBuilder.build()) ;
}
}
步骤 4 − 将以下代码添加到 Manifests/AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.app.sample"> <uses-permission android:name="android.permission.VIBRATE" /> <uses-permission android:name = "android.permission.RECEIVE_BOOT_COMPLETED" /> <application android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
让我们尝试运行您的应用程序。假设您已将实际的 Android 移动设备连接到电脑。要从 Android Studio 运行该应用程序，请打开项目的某个 Activity 文件，然后点击工具栏上的"运行"
图标。选择您的移动设备作为选项，然后检查您的移动设备是否显示您的默认屏幕 −
点击此处下载项目代码。
