新设计模式——规格模式

规格模式

规格模式（Specification Pattern）：它是组合模式的一种特殊应用。同时，每个规格书都是一个策略，它完成了一系列逻辑的封装。

抽象规格书ISpecification：

public interface ISpecification {
    //候选者是否满足要求 
    public boolean isSatisfiedBy(Object candidate); 
    //and操作 
    public ISpecification and(ISpecification spec); 
    //or操作 
    public ISpecification or(ISpecification spec); 
    //not操作 
    public ISpecification not(); 
}

组合规格书CompositeSpecification：

public abstract class CompositeSpecification implements ISpecification { 
    //是否满足条件由实现类实现 
    public abstract boolean isSatisfiedBy(Object candidate); 
    //and操作 
    public ISpecification and(ISpecification spec) { 
        return new AndSpecification(this,spec); 
    }
    //not操作 
    public ISpecification not() { 
        return new NotSpecification(this); 
    }
    //or操作 
    public ISpecification or(ISpecification spec) { 
        return new OrSpecification(this,spec); 
    } 
} 

与规格书AndSpecification：

public class AndSpecification extends CompositeSpecification { 
    //传递两个规格书进行and操作 
    private ISpecification left; 
    private ISpecification right; 
    public AndSpecification(ISpecification _left,ISpecification _right){ 
        this.left = _left; 
        this.right = _right; 
    }
    //进行and运算 
    @Override 
    public boolean isSatisfiedBy(Object candidate) { 
        return left.isSatisfiedBy(candidate) && right.isSatisfiedBy(candidate); 
    } 
} 

或规格书OrSpecification：

public class OrSpecification extends CompositeSpecification { 
    //左右两个规格书 
    private ISpecification left; 
    private ISpecification right; 
    public OrSpecification(ISpecification _left,ISpecification _right){ 
        this.left = _left; 
        this.right = _right; 
    }
    //or运算 
    @Override 
    public boolean isSatisfiedBy(Object candidate) { 
        return left.isSatisfiedBy(candidate) || right.isSatisfiedBy(candidate); 
    } 
} 

非规格书NotSpecification：

public class NotSpecification extends CompositeSpecification { 
    //传递一个规格书 
    private ISpecification spec; 
    public NotSpecification(ISpecification _spec){ 
        this.spec = _spec; 
    }
    //not操作 
    @Override 
    public boolean isSatisfiedBy(Object candidate) { 
        return !spec.isSatisfiedBy(candidate); 
    } 
} 

业务规格书BizSpecification：

public class BizSpecification extends CompositeSpecification { 
    //基准对象 
    private Object obj; 
    public BizSpecification(Object _obj){ 
        this.obj = _obj; 
    }
    @Override 
    public boolean isSatisfiedBy(Object candidate) { 
        //根据基准对象和候选对象，进行业务判断，返回boolean 
        return false; 
    } 
} 

public class Client { 
    public static void main(String[] args) { 
        //待分析的对象 
        ArrayList