Jackson 列表反序列化.嵌套列表 [英] Jackson list deserialization. nested Lists

问题描述

我正在创建一个具有嵌套列表的 API.Jackson 似乎是一个很好的创建对象的工具，但我不太清楚如何嵌套一个列表，我想知道它是否可能.

I'm working on creating an API that has nested lists. Jackson seems like a great tool to create objects, but I can't quite figure out how to nest a list, and I'm wondering if its possible.

我的对象看起来像这样.

My object looks like this.

public class Order {
    public String name;
    public List<Item> items;
}

我希望有一种方法可以将其映射到类似于以下内容的 json:

I'm hoping there is a way to map it to json that looks something like:

{
    name : "A name"
    items : { 
        elements : [{
            price : 30
        }]
    }
}

我们希望能够做到这一点，以便我们可以向列表添加属性.

We want to be able to do this so we can add properties to lists.

推荐答案

您可以为 List 编写自定义反序列化器项.见下例:

class ItemsJsonDeserializer extends JsonDeserializer<List<Item>> {

    @Override
    public List<Item> deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        InnerItems innerItems = jp.readValueAs(InnerItems.class);

        return innerItems.elements;
    }

    private static class InnerItems {
        public List<Item> elements;
    }
}

现在，您必须通知杰克逊将其用于您的财产.你可以这样做:

Now, you have to inform Jackson to use it for your property. You can do this in this way:

public class Order {
  public String name;
  @JsonDeserialize(using = ItemsJsonDeserializer.class)
  public List<Item> items;
}

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