本文主要研究一下dddsample-core的modelgit
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接口定義了sameIdentityAs方法
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接口定義了sameValueAs方法
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實現了ValueObject接口,sameValueAs方法經過equals方法判斷
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枚舉實現了ValueObject接口,其sameValueAs方法經過equals判斷
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接口定義了sameEventAs方法
dddsample-core定義了Entity、ValueObject、DomainEvent接口,它們分別定義了sameIdentityAs、sameValueAs、sameEventAs方法。github