sequence

This paper mainly studies the model of DDDsample-core

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);

}
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Entity interface defines the sameIdentityAs method

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);

}
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The ValueObject interface defines the sameValueAs method

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 } }Copy the code

TrackingId implements the ValueObject interface, and the sameValueAs method is evaluated through equals

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); }}Copy the code

The Type enumeration implements the ValueObject interface, whose sameValueAs method is evaluated by equals

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);

}
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The DomainEvent interface defines the sameEventAs method

summary

Dddsample-core defines the Entity, ValueObject, and DomainEvent interfaces that define the sameIdentityAs, sameValueAs, and sameEventAs methods, respectively.

doc

  • dddsample-core