杰克逊定制解串器映射 [英] Jackson custom deserializer mapping

问题描述

我需要反序列化一些json，它可以包含一个对象数组[{}，{}]或一个对象{}。请参阅我的问题。以下是我要做的事情：

I need to deserialize some json which can contain either an array of objects [{},{}] or a single object {}. See my question. Here is what I'm trying to do :

    public class LocationDeserializer extends JsonDeserializer<List<Location>>{

    @Override
    public List<Location> deserialize(JsonParser jp,
        DeserializationContext ctxt) throws IOException
    {
        List<Location> list = new ArrayList<Location>();
        if(!jp.isExpectedStartArrayToken()){
            list.add(...);
        }else{
            //Populate the list
        }

        return list;
    }

但我被困在这里。如何重新映射对象？如何告诉杰克逊使用这个解串器作为属性位置？

But I'm getting stuck here. How can I remap the object? And how to tell Jackson to use this deserializer for the attribute "location"?

以下是Json的外观：

Here is how the Json can look :

{

"location":
    [
        {
            "code":"75",
            "type":"1"
        },
        {
            "code":"77",
            "type":"1"
        }
    ]
}

或

{
"location":
        {
            "code":"75",
            "type":"1"
        }
}

推荐答案

我不知道你的JSON是什么样的，但我认为使用 ObjectNode 比使用 JsonDeserializer 容易得多。这样的事情：

I don't know what your JSON looks like, but I think using ObjectNode is a lot easier for this case than using JsonDeserializer. Something like this:

ObjectNode root = mapper.readTree("location.json");
if (root.getNodeType() == JsonNodeType.ARRAY) {
  //Use a get and the JsonNode API to traverse the tree to generate List<Location>
}
else {
  //Use a get and the JsonNode API to traverse the tree to generate single Location or a one-element List<Location>
}

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