领域事件相关建模。

plusone-basic/plusone-basic-domain/src/main/java/xyz/zhouxy/plusone/domain/DomainEvent.java

@@ -17,8 +17,8 @@ import lombok.Getter;
  */
 @Getter
 public abstract class DomainEvent {
-    private String identifier;
-    private long happenedAt;
+    private final String identifier;
+    private final long happenedAt;
 
     protected DomainEvent() {
         this.identifier = UUID.randomUUID().toString();

plusone-basic/plusone-basic-domain/src/main/java/xyz/zhouxy/plusone/domain/Entity.java

@@ -5,6 +5,8 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 
+import xyz.zhouxy.plusone.commons.annotation.Overridable;
+
 /**
  * 实体
  *
@@ -26,7 +28,29 @@ public abstract class Entity<ID extends Serializable> {
 
     public abstract Optional<ID> getId();
 
-    protected void addDomainEvent(DomainEvent domainEvent) {
+    protected final void addDomainEvent(DomainEvent domainEvent) {
         domainEvents.add(domainEvent);
     }
+
+    public final List<DomainEvent> getDomainEvents() {
+        return List.copyOf(domainEvents);
+    }
+
+    @Override
+    @Overridable
+    public boolean equals(Object obj) {
+        return super.equals(obj);
+    }
+
+    @Override
+    @Overridable
+    public int hashCode() {
+        return super.hashCode();
+    }
+
+    @Override
+    @Overridable
+    public String toString() {
+        return super.toString();
+    }
 }

plusone-basic/plusone-basic-domain/src/main/java/xyz/zhouxy/plusone/domain/IDomainEventPublisher.java

@@ -0,0 +1,8 @@
+package xyz.zhouxy.plusone.domain;
+
+public interface IDomainEventPublisher {
+
+    void publish(DomainEvent domainEvent);
+
+    <T extends DomainEvent> void subsrcibe(IDomainEventSubscriber<T> subscriber);
+}

plusone-basic/plusone-basic-domain/src/main/java/xyz/zhouxy/plusone/domain/IDomainEventSubscriber.java

@@ -0,0 +1,11 @@
+package xyz.zhouxy.plusone.domain;
+
+/**
+ * 领域事件消费者
+ */
+public interface IDomainEventSubscriber<T extends DomainEvent> {
+
+    void handleEvent(final T event);
+
+    Class<T> subscribedToEventType();
+}