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本文次要钻研一下dddsample-core的Specification
Specification
public interface Specification<T> { /** * Check if {@code t} is satisfied by the specification. * * @param t Object to test. * @return {@code true} if {@code t} satisfies the specification. */ boolean isSatisfiedBy(T t); /** * Create a new specification that is the AND operation of {@code this} specification and another specification. * @param specification Specification to AND. * @return A new specification. */ Specification<T> and(Specification<T> specification); /** * Create a new specification that is the OR operation of {@code this} specification and another specification. * @param specification Specification to OR. * @return A new specification. */ Specification<T> or(Specification<T> specification); /** * Create a new specification that is the NOT operation of {@code this} specification. * @param specification Specification to NOT. * @return A new specification. */ Specification<T> not(Specification<T> specification);}Specification接口定义了isSatisfiedBy、and、or、not办法
AbstractSpecification
/** * Abstract base implementation of composite {@link Specification} with default * implementations for {@code and}, {@code or} and {@code not}. */public abstract class AbstractSpecification<T> implements Specification<T> { /** * {@inheritDoc} */ public abstract boolean isSatisfiedBy(T t); /** * {@inheritDoc} */ public Specification<T> and(final Specification<T> specification) { return new AndSpecification<T>(this, specification); } /** * {@inheritDoc} */ public Specification<T> or(final Specification<T> specification) { return new OrSpecification<T>(this, specification); } /** * {@inheritDoc} */ public Specification<T> not(final Specification<T> specification) { return new NotSpecification<T>(specification); }}AbstractSpecification申明实现Specification，它实现了and、or、not办法
AndSpecification
public class AndSpecification<T> extends AbstractSpecification<T> { private Specification<T> spec1; private Specification<T> spec2; /** * Create a new AND specification based on two other spec. * * @param spec1 Specification one. * @param spec2 Specification two. */ public AndSpecification(final Specification<T> spec1, final Specification<T> spec2) { this.spec1 = spec1; this.spec2 = spec2; } /** * {@inheritDoc} */ public boolean isSatisfiedBy(final T t) { return spec1.isSatisfiedBy(t) && spec2.isSatisfiedBy(t); }}AndSpecification继承了AbstractSpecification，它定义了spec1、spec2属性，其isSatisfiedBy返回的是spec1.isSatisfiedBy(t) && spec2.isSatisfiedBy(t)
OrSpecification
public class OrSpecification<T> extends AbstractSpecification<T> { private Specification<T> spec1; private Specification<T> spec2; /** * Create a new OR specification based on two other spec. * * @param spec1 Specification one. * @param spec2 Specification two. */ public OrSpecification(final Specification<T> spec1, final Specification<T> spec2) { this.spec1 = spec1; this.spec2 = spec2; } /** * {@inheritDoc} */ public boolean isSatisfiedBy(final T t) { return spec1.isSatisfiedBy(t) || spec2.isSatisfiedBy(t); }}OrSpecification继承了AbstractSpecification，它定义了spec1、spec2属性，其isSatisfiedBy返回的是spec1.isSatisfiedBy(t) || spec2.isSatisfiedBy(t)
NotSpecification
public class NotSpecification<T> extends AbstractSpecification<T> { private Specification<T> spec1; /** * Create a new NOT specification based on another spec. * * @param spec1 Specification instance to not. */ public NotSpecification(final Specification<T> spec1) { this.spec1 = spec1; } /** * {@inheritDoc} */ public boolean isSatisfiedBy(final T t) { return !spec1.isSatisfiedBy(t); }}NotSpecification继承了AbstractSpecification，它定义了spec1属性，其isSatisfiedBy返回的是!spec1.isSatisfiedBy(t)
小结
dddsample-core的Specification接口定义了isSatisfiedBy、and、or、not办法；AndSpecification、OrSpecification、NotSpecification继承了AbstractSpecification，实现了Specification接口。
doc
- dddsample-core