java - Jackson Databind 中是否有任何替代品来替代已弃用的属性 SerializationFeature.WRITE_NULL_MAP_VALUES ？

Question

我们正在使用 ObjectMapper 来忽略项目中空映射的序列化

configure(SerializationFeature.WRITE_NULL_MAP_VALUES, false)

但是在 Jackson-Databind 2.9 之后，该属性已贬值，我们正在寻找替代选项。

下面的代码可以替代删除上述属性吗 -

setSerializationInclusion(Include.NON_NULL)

Answer 1

来自documentation :

Deprecated. Since 2.9 there are better mechanism for specifying filtering; specifically using JsonInclude or configuration overrides (see ObjectMapper.configOverride(Class)). Feature that determines whether Map entries with null values are to be serialized (true) or not (false).
NOTE: unlike other SerializationFeatures, this feature cannot be dynamically changed on per-call basis, because its effect is considered during construction of serializers and property handlers.

Feature is enabled by default.

简单的例子:

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Value;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import java.util.HashMap;
import java.util.Map;

public class JsonApp {

    public static void main(String[] args) throws Exception {
        Map<String, Object> map = new HashMap<>();
        map.put("string", "value");
        map.put("int", 1);
        map.put("null1", null);
        map.put(null, null);

        ObjectMapper mapper = new ObjectMapper();
        mapper.enable(SerializationFeature.INDENT_OUTPUT);
        mapper.configOverride(Map.class).setInclude(Value.construct(JsonInclude.Include.NON_NULL, JsonInclude.Include.NON_NULL));

        System.out.println(mapper.writeValueAsString(map));
    }
}

上面的代码打印:

{
  "string" : "value",
  "int" : 1
}