反序列化内部JSON对象

Question

I have a class POJO

Class Pojo {
String id;
String name;
//getter and setter
}

I have a json like

{
    "response" : [
        {
            "id" : "1a",
            "name" : "foo"
        }, 
        {
            "id" : "1b",
            "name" : "bar"
        }
    ]
}

I am using Jackson ObjectMapper for deserialization. How can I get List<Pojo> without creating any other parent class?

If it is not possible, is it possible to get Pojo object which holds just first element of json string ie in this case id="1a" and name="foo" ?

Answer 1

You'll first need to get the array

String jsonStr = "{\"response\" : [ { \"id\" : \"1a\",  \"name\" : \"foo\"},{ \"id\" : \"1b\",\"name\" : \"bar\"  } ]}";
ObjectMapper mapper = new ObjectMapper();
JsonNode node = mapper.readTree(jsonStr);
ArrayNode arrayNode = (ArrayNode) node.get("response");
System.out.println(arrayNode);
List<Pojo> pojos = mapper.readValue(arrayNode.toString(), new TypeReference<List<Pojo>>() {});

System.out.println(pojos);

prints (with a toString() )

[{"id":"1a","name":"foo"},{"id":"1b","name":"bar"}] // the json array 
[id = 1a, name = foo, id = 1b, name = bar] // the list contents

Answer 2

You can use the generic readTree with JsonNode:

ObjectMapper mapper = new ObjectMapper();
JsonNode root = mapper.readTree(json);
JsonNode response = root.get("response");
List<Pojo> list = mapper.readValue(response, new TypeReference<List<Pojo>>() {});