强制 Jackson 反序列化为特定的原始类型 [英] Forcing Jackson to deserialize to specific primitive type

问题描述

我正在使用 Jackson 1.8.3 将以下域对象序列化和反序列化为 JSON

I am serializing and deserializing following domain object to JSON using Jackson 1.8.3

public class Node {
    private String key;
    private Object value;
    private List<Node> children = new ArrayList<Node>();
    /* getters and setters omitted for brevity */
}

然后使用以下代码对对象进行序列化和反序列化

Object is then serialized and deserialized using following code

ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(destination, rootNode);

然后反序列化

mapper.readValue(destination, Node.class);

对象的原始值是字符串、双精度、长整数或布尔值.但是，在序列化和反序列化期间，Jackson 将 Long 值(例如 4)转换为 Integers.

The original values of the object are either Strings, Doubles, Longs or Booleans. However, during serialization and deserialization Jackson transforms Long values (such as 4) to Integers.

我如何强制"Jackson 将数字非十进制值反序列化为 Long 而不是 Integer?

How can I "force" Jackson to deserialize numeric non-decimal values to Long instead of Integer?

推荐答案

如果类型声明为 java.lang.Object，Jackson 使用自然"映射，如果值适合 32 位，则使用整数.除了自定义处理程序之外，您还必须强制包含类型信息(通过在字段/getter 旁边添加 @JsonTypeInfo；或启用所谓的默认类型").

If type is declared as java.lang.Object, Jackson uses 'natural' mapping which uses Integer if value fits in 32 bits. Aside from custom handlers you would have to force inclusion of type information (either by adding @JsonTypeInfo next to field / getter; or by enabling so-called "default typing").

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