这篇文章主要介绍“event-sourcing-cqrs的model有哪些”，在日常操作中，相信很多人在event-sourcing-cqrs的model有哪些问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”event-sourcing-cqrs的model有哪些”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
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public abstract class Event {
private final UUID aggregateId;
private final ZonedDateTime timestamp;
private final int version;
protected Event(UUID aggregateId, ZonedDateTime timestamp, int version) {
this.aggregateId = checkNotNull(aggregateId);
this.timestamp = checkNotNull(timestamp);
this.version = version;
}
public UUID getAggregateId() {
return aggregateId;
}
public ZonedDateTime getTimestamp() {
return this.timestamp;
}
public int getVersion() {
return version;
}
}Event定义了aggregateId、timestamp、version属性
public interface EventStore {
void store(UUID aggregateId, List<Event> newEvents, int baseVersion)
throws OptimisticLockingException;
List<Event> load(UUID aggregateId);
}EventStore接口定义了store、load方法
public abstract class Aggregate {
private UUID id;
private int baseVersion;
private List<Event> newEvents;
protected Aggregate(UUID id) {
this(id, emptyList());
}
protected Aggregate(UUID id, List<Event> eventStream) {
checkNotNull(id);
checkNotNull(eventStream);
this.id = id;
eventStream.forEach(e -> {
apply(e);
this.baseVersion = e.getVersion();
});
this.newEvents = new ArrayList<>();
}
protected void applyNewEvent(Event event) {
checkArgument(event.getVersion() == getNextVersion(),
"New event version '%s' does not match expected next version '%s'",
event.getVersion(), getNextVersion());
apply(event);
newEvents.add(event);
}
private void apply(Event event) {
try {
Method method = this.getClass().getDeclaredMethod("apply", event.getClass());
method.setAccessible(true);
method.invoke(this, event);
} catch (InvocationTargetException e) {
Throwables.propagate(e.getCause());
} catch (NoSuchMethodException | IllegalAccessException e) {
throw new UnsupportedOperationException(
format("Aggregate '%s' doesn't apply event type '%s'", this.getClass(), event.getClass()),
e);
}
}
public UUID getId() {
return id;
}
public int getBaseVersion() {
return baseVersion;
}
public List<Event> getNewEvents() {
return ImmutableList.copyOf(newEvents);
}
protected int getNextVersion() {
return baseVersion + newEvents.size() + 1;
}
}Aggregate定义了id、baseVersion、newEvents属性；其applyNewEvent方法会执行apply(event)及newEvents.add(event)；apply方法通过反射执行event的apply方法
public abstract class ValueObject {
@Override
public boolean equals(Object o) {
return EqualsBuilder.reflectionEquals(this, o);
}
@Override
public int hashCode() {
return HashCodeBuilder.reflectionHashCode(this);
}
@Override
public String toString() {
return ToStringBuilder.reflectionToString(this, ToStringStyle.SHORT_PREFIX_STYLE);
}
}ValueObject覆盖了equals、hashCode、toString方法
public interface Specification<T> {
boolean isSatisfiedBy(T value);
}Specification接口定义了isSatisfiedBy方法
到此，关于“event-sourcing-cqrs的model有哪些”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注亿速云网站，小编会继续努力为大家带来更多实用的文章！
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原文链接：https://my.oschina.net/go4it/blog/5021238
