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本文次要钻研一下dddsample-core的model
Entity
public interface Entity<T> { /** * Entities compare by identity, not by attributes. * * @param other The other entity. * @return true if the identities are the same, regardless of other attributes. */ boolean sameIdentityAs(T other);}Entity接口定义了sameIdentityAs办法
ValueObject
public interface ValueObject<T> extends Serializable { /** * Value objects compare by the values of their attributes, they don't have an identity. * * @param other The other value object. * @return <code>true</code> if the given value object's and this value object's attributes are the same. */ boolean sameValueAs(T other);}ValueObject接口定义了sameValueAs办法
TrackingId
public final class TrackingId implements ValueObject<TrackingId> { private String id; /** * Constructor. * * @param id Id string. */ public TrackingId(final String id) { Validate.notNull(id); this.id = id; } /** * @return String representation of this tracking id. */ public String idString() { return id; } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; TrackingId other = (TrackingId) o; return sameValueAs(other); } @Override public int hashCode() { return id.hashCode(); } @Override public boolean sameValueAs(TrackingId other) { return other != null && this.id.equals(other.id); } @Override public String toString() { return id; } TrackingId() { // Needed by Hibernate }}TrackingId实现了ValueObject接口，sameValueAs办法通过equals办法判断
Type
public enum Type implements ValueObject<Type> { LOAD(true), UNLOAD(true), RECEIVE(false), CLAIM(false), CUSTOMS(false); private final boolean voyageRequired; /** * Private enum constructor. * * @param voyageRequired whether or not a voyage is associated with this event type */ private Type(final boolean voyageRequired) { this.voyageRequired = voyageRequired; } /** * @return True if a voyage association is required for this event type. */ public boolean requiresVoyage() { return voyageRequired; } /** * @return True if a voyage association is prohibited for this event type. */ public boolean prohibitsVoyage() { return !requiresVoyage(); } @Override public boolean sameValueAs(Type other) { return other != null && this.equals(other); } }Type枚举实现了ValueObject接口，其sameValueAs办法通过equals判断
DomainEvent
public interface DomainEvent<T> { /** * @param other The other domain event. * @return <code>true</code> if the given domain event and this event are regarded as being the same event. */ boolean sameEventAs(T other);}DomainEvent接口定义了sameEventAs办法
小结
dddsample-core定义了Entity、ValueObject、DomainEvent接口，它们别离定义了sameIdentityAs、sameValueAs、sameEventAs办法。
doc
- dddsample-core