如何使用 Jackson 反序列化以下 json

发布于 2024-10-28 21:41:28 字数 742 浏览 1 评论 0原文

我有以下 json:，

{
  "id":"myid",
  "fields":{
    "body":"text body"
    }
}

将其反序列化为以下 Java 类：

class TestItem {
private String id;
private String body;

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public String getBody() {
    return body;
}

public void setBody(String body) {
    this.body = body;
}

我想使用 Jackson Json 反序列化器。这不起作用，因为 body 字段嵌套在 fields 内部类中。

我无法更改 json 结构，因此有什么方法（可能使用注释）可以将 body 字段从 TestItem.fields.body 重新映射到 TestItem.body？

编辑： 我应该说这是一个更大的类层次结构的一部分，练习的目的是减少它的深度。换句话说，我知道我可以声明一个内部类，然后访问它，但这不是我想要实现的目标。

原文

I have the following json:

{
  "id":"myid",
  "fields":{
    "body":"text body"
    }
}

which I want to deserialize into the following Java class:

class TestItem {
private String id;
private String body;

public String getId() {
    return id;
}

public void setId(String id) {
    this.id = id;
}

public String getBody() {
    return body;
}

public void setBody(String body) {
    this.body = body;
}

using the Jackson Json deserializer. This doesn't work because the body field is nested inside a fields inner class.

I can't change the json structure, so is there any way (perhaps using annotations) I can remap of the body field up from TestItem.fields.body to TestItem.body?

Edit:
I should have said this is part of a larger class hierarchy and the aim of the excercise is to reduce the depth of it. In other words, I know that I COULD declare an inner class and then access that, but that is not what I'm trying to achieve.

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我三岁 2024-11-04 21:41:28

有几个功能请求（如果实现）将允许有限的一级包装/展开。但目前还没有声明性的方法来做到这一点。在某种程度上，这是边缘情况，因为这涉及数据转换而不是数据绑定（不幸的是，我想不出好的对象转换库，因此那里可能存在一些差距）。

那么，通常要做的是进行两阶段绑定：首先绑定到中间类型（通常是 java.util.Map 或 jackson JsonNode（树模型））；修改它们，然后从该类型转换为实际结果。例如这样的事情：

JsonNode root = mapper.readTree(jsonSource);
// modify it appropriately (add, remove, move nodes)
MyBean bean = mapper.convertValue(root, MyBean.class);

There are couple of feature requests that (if implemented) would allow limited one-level wrapping/unwrapping. But currently there is no declarative way to do this. And to some degree it is edge case, since this goes into data transformation as opposed to data binding (unfortunately I can't think of good object transformation libs, so there may be bit of gap there).

What is usually done, then, is to do two-phase binding: first into intermediate types (often java.util.Map, or jackson JsonNode (Tree model)); modify those, and then convert from this type to actual result. For example something like this:

JsonNode root = mapper.readTree(jsonSource);
// modify it appropriately (add, remove, move nodes)
MyBean bean = mapper.convertValue(root, MyBean.class);

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