Java 找不到类型 [简单类型，类 com.comcast.ivr.core.domain.AutoHandlingSlotKey] 的（映射）密钥解串器
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Can not find a (Map) Key deserializer for type [simple type, class com.comcast.ivr.core.domain.AutoHandlingSlotKey]
提问by Mick Knutson
I have a domain object that has a Map:
我有一个具有 Map 的域对象：
private Map<AutoHandlingSlotKey, LinkedHashSet<AutoFunction>> autoHandling;
When I serialize the object, I get this:
当我序列化对象时，我得到了这个：
"autoHandling" : [ "java.util.HashMap", {
} ],
This Map's key is a custom Object:
这个 Map 的键是一个自定义对象：
public class AutoHandlingSlotKey implements Serializable {
private FunctionalArea slot; // ENUM
private String returnView; // ENUM
So, I am not sure how to correct this issue I keep getting when I deserialize the object:
因此，我不确定如何纠正反序列化对象时不断遇到的这个问题：
org.codehaus.Hymanson.map.JsonMappingException: Can not find a (Map) Key deserializer for type [simple type, class com.comcast.ivr.core.domain.AutoHandlingSlotKey]
Can someone help me to understand how to correct this issue if I do NOThave access to the domain object to modify?
有人能帮我可以了解如何解决此问题，如果我不能够访问域对象要修改？
采纳答案by StaxMan
By default, Hymanson tries to serialize Java Maps as JSON Objects (key/value pairs), so Map key object must be somehow serialized as a String; and there must be matching (and registered) key deserializer. Default configuration only supports a small set of JDK types (String, numbers, enum). So mapper has no idea as to how to take a String and create AutoHandlingSlotKey out of it. (in fact I am surprised that serializer did not fail for same reason)
默认情况下，Hymanson 尝试将 Java Maps 序列化为 JSON 对象（键/值对），因此 Map 键对象必须以某种方式序列化为 String；并且必须有匹配（和注册）的密钥解串器。默认配置仅支持一小组 JDK 类型（字符串、数字、枚举）。所以映射器不知道如何获取一个字符串并从中创建 AutoHandlingSlotKey。（事实上，我很惊讶序列化程序并没有因为同样的原因而失败）
Two obvious ways to solve this are:
解决此问题的两种明显方法是：
- Implement and register a "key deserializer"
- Implement and register a custom deserializer for Maps.
- 实现并注册一个“key deserializer”
- 为 Maps 实现并注册自定义反序列化器。
In your case it is probably easier to do former. You may also want to implement custom key serializer, to ensure keys are serializer in proper format.
在你的情况下，做前者可能更容易。您可能还想实现自定义密钥序列化程序，以确保密钥是正确格式的序列化程序。
The easiest way to register serializers and deserializers is by Module interfacethat was added in Hymanson 1.7 (and extended in 1.8 to support key serializers/deserializers).
注册序列化器和反序列化器的最简单方法是通过在 Hymanson 1.7 中添加的Module 接口（并在 1.8 中扩展以支持关键序列化器/反序列化器）。
回答by estebanrv
This was asked a long time ago, and is the first google result when looking up the error, but the accepted answer has no code and might be confusing for a Hymanson beginner (me). I eventually found this answerthat helped.
这是很久以前问过的，是查找错误时的第一个谷歌结果，但接受的答案没有代码，可能会让Hyman逊初学者（我）感到困惑。我最终找到了这个有帮助的答案。
So, as stated in accepted answer, Implementing and register a "key deserializer" is the way to go. You can do this like this.
因此，如已接受的答案中所述，实施和注册“密钥解串器”是要走的路。你可以这样做。
SimpleModule simpleModule = new SimpleModule();
simpleModule.addKeyDeserializer(YourClass.class, new YourClassKeyDeserializer());
objectMapper.registerModule(simpleModule);
And for the class, all you have to do is:
而对于课堂，你所要做的就是：
class YourClassKeyDeserializer extends KeyDeserializer
{
@Override
public Object deserializeKey(final String key, final DeserializationContext ctxt ) throws IOException, JsonProcessingException
{
return null; // replace null with your logic
}
}
That's it! No annotation on classes, not custom deserializer for maps, etc.
就是这样！类上没有注释，地图上没有自定义反序列化器等。
