Jackson 在反序列化期间动态过滤属性

问题描述

我有一个 REST WS 来更新接收 JSON 字符串作为输入的 bean 对象.

I have a REST WS to update a bean object which receives a JSON string as input.

ABean entity = svc.findEntity(...);
objectMapper.readerForUpdating(entity).readValue(json);
[...]
svc.save(entity);

ABean 是一种复杂类型，还包含其他对象，例如:

class ABean {
    public BBean b;
    public CBean c;

    public String d;
}

svc.save(...) 将保存 bean 和嵌入的对象.

svc.save(...) will save the bean and the embedded objects.

出于安全原因，我想过滤掉一些可以由 JSON 字符串更新的属性，但我想动态执行此操作，以便对于每个 WS(或用户角色)我可以决定要阻止哪些属性被更新(所以我不能简单地使用杰克逊视图)

For security reasons I want to filter out some of the properties that can be updated by the JSON string, but I want to do this dynamically, so that for every WS (or user Role) I can decide which properties to prevent to be updated (so I can't simply use the Jackson Views)

总而言之，有什么方法可以在 JSON 反序列化期间动态过滤掉属性?

To summarize, is there any way I can dynamically filter out properties during JSON Deserialization?

推荐答案

另一种方法是使用 BeanDeserializerModifier:

Another way is using BeanDeserializerModifier:

private static class BeanDeserializerModifierForIgnorables extends BeanDeserializerModifier {

        private java.lang.Class<?> type;
        private List<String> ignorables;

        public BeanDeserializerModifierForIgnorables(java.lang.Class clazz, String... properties) {
            ignorables = new ArrayList<>();
            for(String property : properties) {
                ignorables.add(property);
            }
            this.type = clazz;
        }

        @Override
        public BeanDeserializerBuilder updateBuilder(
                DeserializationConfig config, BeanDescription beanDesc,
                BeanDeserializerBuilder builder) {
            if(!type.equals(beanDesc.getBeanClass())) {
                return builder;
            }

            for(String ignorable : ignorables) {
                builder.addIgnorable(ignorable);
            }

            return builder;
        }

        @Override
        public List<BeanPropertyDefinition> updateProperties(
                DeserializationConfig config, BeanDescription beanDesc,
                List<BeanPropertyDefinition> propDefs) {
            if(!type.equals(beanDesc.getBeanClass())) {
                return propDefs;
            }

            List<BeanPropertyDefinition> newPropDefs = new ArrayList<>();
            for(BeanPropertyDefinition propDef : propDefs) {
                if(!ignorables.contains(propDef.getName())) {
                    newPropDefs.add(propDef);
                }
            }
            return newPropDefs;
        }
    }

您可以使用以下命令将修改器注册到 ObjectMapper:

You can register the modfier to the ObjectMapper with:

BeanDeserializerModifier modifier = new BeanDeserializerModifierForIgnorables(YourType.class, "name");
DeserializerFactory dFactory = BeanDeserializerFactory.instance.withDeserializerModifier(modifier);
ObjectMapper mapper = new ObjectMapper(null, null, new DefaultDeserializationContext.Impl(dFactory));

然后定义的属性被忽略.如果使用 @JsonAnySetter 注释，则可以忽略 updateBuilder 方法.

Then the defined properties are ignored. You can ignore the updateBuilder method if you use the @JsonAnySetter annotation.

您好，马丁

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