Jackson 反序列化抽象类

1 回答

• 4

  是的，您可以为抽象类编写自己的Custom Deserializer . 这个反序列化器必须确定JSON代表哪个具体类，并实例化它的实例 .

  可能有更惯用的方法，但这是一个快速而肮脏的例子：

  public class Test {
      public static void main(String... args) throws IOException {
          final ObjectMapper mapper = new ObjectMapper();
          final SimpleModule module = new SimpleModule();
          module.addDeserializer(Animal.class, new AnimalDeserializer());
          mapper.registerModule(module);
  
          final String json = "{\"aGoodBoy\": true}";
          final Animal animal = mapper.readValue(json, Animal.class);
          System.out.println(animal.talk());
      }
  
      public static abstract class Animal {
          public abstract String talk();
      }
  
      public static class Fish extends Animal {
          @Override
          public String talk() {
              return "blub blub I'm a dumb fish";
          }
      }
  
      public static class Dog extends Animal {
          public boolean aGoodBoy;
  
          @Override
          public String talk() {
              return "I am a " + (aGoodBoy ? "good" : "bad") + " dog";
          }
      }
  
      public static class AnimalDeserializer extends StdDeserializer<Animal> {
          protected AnimalDeserializer() {
              this(null);
          }
  
          protected AnimalDeserializer(final Class<?> vc) {
              super(vc);
          }
  
          @Override
          public Animal deserialize(final JsonParser parser, final DeserializationContext context)
          throws IOException, JsonProcessingException {
              final JsonNode node = parser.getCodec().readTree(parser);
              final ObjectMapper mapper = (ObjectMapper)parser.getCodec();
              if (node.has("aGoodBoy")) {
                  return mapper.treeToValue(node, Dog.class);
              } else {
                  return mapper.treeToValue(node, Fish.class);
              }
          }
      }
  }
  

  回复于 2024-04-27T07:21:56+08:00