Java 类的Jackson反序列化程序<；？扩展Foo>；

我想要一个用于类文本的序列化器和反序列化器。它应该从/映射到JSON字符串。它还应该与泛型类一起工作

我尝试编写自定义反序列化程序，但它处理所有类，而不仅仅是我想要的类：

public class MyDeserializer extends JsonDeserializer<Class<? extends Foo>> {
    public Class<? extends Foo> deserialize(JsonParser jp, DeserializationContext ctxt) 
        throws IOException, JsonProcessingException {

        String token = jp.getText();
        switch(token) {
            case "FOO": return Foo.class;
            case "BAR": return Bar.class;
        }
        return null;
    }
}

JSON:

ObjectMapper用法：

MyPOJO pojo = new MyPOJO();
pojo.fooType = Foo.class;

ObjectMapper om = new ObjectMapper();
String json = om.writeValueAsString(pojo);

---

您试图实现的目标似乎是不可能的，因为在运行时，您的类

MyDeserializer

被视为

JsonDeserializer

，而您的字段

FootType

只是类型

class

而不是类型

class

---

在您的情况下，最好的解决方案是注释类型为

classe的字段。您是否可以为Json POJO添加代码并使用
ObjectMapper
？添加一些代码如果您不想使用@JsonDeserialize，您能否仅在需要的地方使用@JsonIgnore？（即瞬态&不可串行化）@Shine:no。如果它不是
类的类型，我应该可以使用
jsonderializer
{
    "fooType": "FOO"
}

MyPOJO pojo = new MyPOJO();
pojo.fooType = Foo.class;

ObjectMapper om = new ObjectMapper();
String json = om.writeValueAsString(pojo);

ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule("MyModule")
    .addDeserializer(Class.class, new MyDeserializer());
mapper.registerModule(module);

public class MyDeserializer extends JsonDeserializer<Class<?>>  {

    // The default deserializer for a property of type Class
    private final FromStringDeserializer.Std defaultDeserializer;

    public MyDeserializer() {
        // Set the default deserializer
        this.defaultDeserializer = FromStringDeserializer.findDeserializer(Class.class);
    }

    public Class<?> deserialize(JsonParser jp, DeserializationContext ctxt) 
        throws IOException, JsonProcessingException {
        // Check whether we should used the custom or default deserializer
        // based on the bean class
        if (accept(jp.getCurrentValue().getClass())) {
            // The custom deserializer
            String token = jp.getText();
            switch(token) {
                case "FOO": return Foo.class;
                case "BAR": return Bar.class;
            }
            return null;
        }
        // Call the default deserializer
        return (Class<?>) defaultDeserializer.deserialize(jp, ctxt);
    }

    // Returns true if this bean class has fields of type Class that must
    // be deserialized with the custom deserializer, false otherwise
    public boolean accept(Class<?> beanClass) {
        // Implement your logic here
        // You could for example have all the bean classes in a Set and 
        // check that the provided class is in the Set 
    }
}