Added Post system. Notification system

src/main/java/site/easystartup/web/notification/event/EventHandler.java

@@ -0,0 +1,12 @@
+package site.easystartup.web.notification.event;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+
+@Target(ElementType.METHOD)
+public @interface EventHandler {
+}

src/main/java/site/easystartup/web/notification/event/NotificationEvent.java

@@ -0,0 +1,9 @@
+package site.easystartup.web.notification.event;
+
+public interface NotificationEvent {
+    void invoke();
+
+    String getRecipient();
+
+    String getMessage();
+}

src/main/java/site/easystartup/web/notification/event/NotificationEventManager.java

@@ -0,0 +1,36 @@
+package site.easystartup.web.notification.event;
+
+import org.springframework.context.annotation.Scope;
+import org.springframework.stereotype.Component;
+
+import java.lang.reflect.InvocationTargetException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+@Component
+@Scope("singleton")
+public class NotificationEventManager {
+    private List<NotificationListener> listeners = new ArrayList<>();
+
+    public void registerListener(NotificationListener listener) {
+        listeners.add(listener);
+    }
+
+    public void removeListener(NotificationListener listener) {
+        listeners.remove(listener);
+    }
+
+    public void notifyListeners(Class<? extends NotificationEvent> event) {
+        listeners.forEach(listener -> Arrays.stream(listener.getClass().getMethods()).
+                filter(m -> m.isAnnotationPresent(EventHandler.class)).forEach(method -> {
+                    if (method.getParameterTypes()[0].equals(event.getClass())) {
+                        try {
+                            method.invoke(listener, event);
+                        } catch (IllegalAccessException | InvocationTargetException e) {
+                            throw new RuntimeException(e);
+                        }
+                    }
+                }));
+    }
+}

src/main/java/site/easystartup/web/notification/event/NotificationListener.java

@@ -0,0 +1,4 @@
+package site.easystartup.web.notification.event;
+
+public interface NotificationListener {
+}

src/main/java/site/easystartup/web/notification/event/realtime/RealTimeListener.java

@@ -0,0 +1,26 @@
+package site.easystartup.web.notification.event.realtime;
+
+import lombok.RequiredArgsConstructor;
+import org.springframework.beans.factory.annotation.Autowired;
+import site.easystartup.web.notification.domian.Notification;
+import site.easystartup.web.notification.event.EventHandler;
+import site.easystartup.web.notification.event.NotificationEvent;
+import site.easystartup.web.notification.event.NotificationListener;
+import site.easystartup.web.notification.repo.NotificationRepo;
+import site.easystartup.web.notification.service.NotificationService;
+import site.easystartup.web.post.domain.event.RepostEvent;
+
+@RequiredArgsConstructor(onConstructor_ = @Autowired)
+public class RealTimeListener implements NotificationListener {
+    private final NotificationService notificationService;
+
+    private final NotificationRepo repo;
+
+    @EventHandler
+    public void onEvent(NotificationEvent event) {
+        Notification notification = new Notification();
+        notification.setText(event.getMessage());
+        notification.setRecipient(event.getRecipient());
+        notificationService.sendNotification(repo.save(notification));
+    }
+}