如何使用 Jackson 反序列化对象数组

2022-01-30 00:00:00 json java jackson

Jackson 数据绑定文档 表明 Jackson 支持反序列化所有支持类型的数组"，但我可以'不知道确切的语法.

The Jackson data binding documentation indicates that Jackson supports deserialising "Arrays of all supported types" but I can't figure out the exact syntax for this.

对于单个对象，我会这样做:

For a single object I would do this:

//json input
{
    "id" : "junk",
    "stuff" : "things"
}

//Java
MyClass instance = objectMapper.readValue(json, MyClass.class);

现在对于一个数组我想这样做:

Now for an array I want to do this:

//json input
[{
    "id" : "junk",
    "stuff" : "things"
},
{
    "id" : "spam",
    "stuff" : "eggs"
}]

//Java
List<MyClass> entries = ?

有人知道是否有一个神奇的缺失命令吗?如果不是，那么解决办法是什么?

Anyone know if there is a magic missing command? If not then what is the solution?

推荐答案

首先创建一个mapper:

First create a mapper :

import com.fasterxml.jackson.databind.ObjectMapper;// in play 2.3
ObjectMapper mapper = new ObjectMapper();

作为数组:

MyClass[] myObjects = mapper.readValue(json, MyClass[].class);

作为列表:

List<MyClass> myObjects = mapper.readValue(jsonInput, new TypeReference<List<MyClass>>(){});

另一种指定List类型的方法:

Another way to specify the List type:

List<MyClass> myObjects = mapper.readValue(jsonInput, mapper.getTypeFactory().constructCollectionType(List.class, MyClass.class));

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