java - 如何将参数传递到工厂以创建对象？

Question

我有RecipientTypesFactory这将创建 RecipientType 类型的对象。对于 RecipientType s 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它本身看起来如下:

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 的实际定义及其层次结构，因为我认为它不是很重要。

现在我有了 Controller :

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及其 creators一无所知CreateMailingController的dynamicGroupId和staticGroupId值(value)观。这些值是由某些用户通过网络界面设置的。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它的创造者是 Spring Bean 。

问题:我如何传递 dynamicGroupId 的值和staticGroupId灵活到工厂，免写信switch-case喜欢代码？这可能吗？

也许还有另一种说法可以达到这个目的。事实上工厂正在创建一个对象的原型(prototype)。

Answer 1

您可以使用 map 来避免切换情况，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();
    }