我有一个包含Map(带非String键)和其他一些字段的Class。
I have a Class that contains a Map (with non String key) and some other fields.
public class MyClass() { private Map<KeyObject, OtherObject> map; private String someField; public MyClass(Map<KeyObject, OtherObject> map, String someField) { this.map = map; this.someField = someField; } // Getters & Setters }我想使用Jackson序列化和反序列化这个类。 我看到了不同的方法,并决定尝试使用 jackson模块。
I would like to serialize and deserialize this class using Jackson. I saw a different ways of doing that and decided to try using jackson modules.
我跟着这篇文章并扩展了JsonDeserializer和JsonSerializer。问题是这些类应该键入,所以它应该看起来像
I followed this post and extended JsonDeserializer and JsonSerializer. The problem is that those classes should be typed, so it should look like
public class keyDeserializer extends JsonDeserializer<Map<KeyObject, OtherObject>> { ... }KeySerializer的相同内容。
The same for the KeySerializer.
然后添加到模块:
module.addSerializer(new keySerializer()); module.addDeserializer(Map.class, new keyDeserializer());但这显然是错误的,因为我得到了一个例外:
But this is wrong apparently since I'm getting an exception:
keySerializer does not define valid handledType() -- must either register with method that takes type argument or make serializer extend 'org.codehaus.jackson.map.ser.std.SerializerBase'我可以将我的序列化器和反序列化器输入 MyClass ,但后来我不得不手动解析所有这些,这是不合理的。
I could have my serializer and deserializer to be typed to MyClass, but then I had to manually parse all of it, which is not reasonable.
更新:
我设法通过使用注释绕过了代码中的模块创建
I managed to bypass the module creation in the code by using annotations
@JsonDeserialize(using = keyDeserializer.class) @JsonSerialize(using = keySerializer.class) private Map<KeyObject, OtherObject> map;但是我必须自己从toString()输出序列化/反序列化整个地图结构。所以尝试了不同的注释:
But then I have to serialize/deserialize the whole map structure on my own from the toString() output. So tried a different annotation:
@JsonDeserialize(keyUsing = MyKeyDeserializer.class) private Map<KeyObject, OtherObject> map;MyKeyDeserializer扩展 org.codehaus.jackson.map.KeyDeserializer 并覆盖方法
Where MyKeyDeserializer extends org.codehaus.jackson.map.KeyDeserializer and overriding the method
public Object deserializeKey(String key, DeserializationContext ctxt) throws IOException, JsonProcessingException {...}然后再次从我的密钥类的toString()输出反序列化我的密钥。
Then manually deserializing my key but again from the toString() output of my key class.
这不是最佳的(这种对toString()方法的依赖)。有更好的方法吗?
This is not optimal (this dependency on the toString() method). Is there a better way?
推荐答案结束使用此序列化程序:
Ended up using this serializer:
public class MapKeySerializer extends SerializerBase<Object> { private static final SerializerBase<Object> DEFAULT = new StdKeySerializer(); private static final ObjectMapper mapper = new ObjectMapper(); protected MapKeySerializer() { super(Object.class); } @Override public JsonNode getSchema(SerializerProvider provider, Type typeHint) throws JsonMappingException { return DEFAULT.getSchema(provider, typeHint); } @Override public void serialize(Object value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonGenerationException { if (null == value) { throw new JsonGenerationException("Could not serialize object to json, input object to serialize is null"); } StringWriter writer = new StringWriter(); mapper.writeValue(writer, value); jgen.writeFieldName(writer.toString()); } }此解串器:
public class MapKeyDeserializer extends KeyDeserializer { private static final ObjectMapper mapper = new ObjectMapper(); @Override public Object deserializeKey(String key, DeserializationContext ctxt) throws IOException, JsonProcessingException { return mapper.readValue(key, MyObject.class); } }注释我的地图:
@JsonDeserialize(keyUsing = MapKeyDeserializer.class) @JsonSerialize(keyUsing = MapKeySerializer.class) private Map<KeyObject, OtherObject> map;这是对我有用的解决方案,希望这有助于其他人。
This is the solution that worked for me, hope this helps other.
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