Question

我有RecipientTypesFactory，它将创建RecipientType类型的对象。对于RecipientType对象，我有以下层次结构：

public interface RecipientType{
    public abstract Object accept(RecipientTypeVisitor v);
}

public class DynamicGroupType implemetns RecipientType{

    private Integer dynamicGroupId;

    public Object accept(RecipientTypeVisitor visitor){
        return visitor.visit(this);
    }
    //GET, SET
}

public class StaticGroupType implements RecipientType{

    private Integer staticGroupId;

    public Object accept(RecipientTypeVisitor visitor){
        return visitor.visit(this);
    }
    //GET, SET
}

RecipientTypesFactory本身如下：

public enum RecipientTypeEnum {
    STATIC_GROUP, DYNAMIC_GROUP
}

public class RecipientTypesFactory{
    private Map<RecipientTypeEnum, RecipientTypeCreator> creators;

    public RecipientType createRecipientType(RecipientTypeEnum t){
        return creators.get(t).create();
    }
}

我不会提供RecipientTypeCreator及其等级的实际定义，因为我认为它非常重要。

现在我有了控制器：

public class CreateMailingController{
    private RecipientTypesFactory recipientTypesFactory;
    private Integer dynamicGroupId;
    private Integer staticGroupId;
    private RecipientTypeEnum selectedType;

    //GET, SET, other staff

    public void createMailing(){
        Type t = recipientTypesFactory.createRecipientType(selectedType);
        //How to initialize t's field with an appropriate value?
    }
}

事情是RecipientTypesFactory，其creators对CreateMailingController dynamicGroupId和staticGroupId值一无所知。这些值是由某些用户从Web界面设置的。因此，工厂无法初始化要使用这些值创建的类型的相应字段。

RecipientTypesFactory及其创作者是春豆。

问题：如何以灵活的方式将dynamicGroupId和staticGroupId的值传递给工厂并避免使用{{1}像代码？这可能吗？

也许还有另一种用于此目的的模式。事实上，工厂正在创建一个对象的原型。

Answer 1

您可以使用map来避免切换案例，如下所示：

private static final Map<String, RecipientType> factoryMap = Collections
            .unmodifiableMap(new HashMap<String, RecipientType>() {
                {
                    put("dynamicGroupId", new RecipientType() {
                        public RecipientType accept() {
                            return new DynamicGroupType();
                        }
                    });
                    put("staticGroupId", new RecipientType() {
                        public RecipientType accept() {
                            return new StaticGroupType();
                        }
                    });
                }
            });

    public RecipientType createRecipientType(String type) {
        RecipientType factory = factoryMap.get(type);
        if (factory == null) {

        }
        return factory.accept();
    }

如何将params传递给Factory进行对象创建？

1 个答案: