无法反序列化java.time.instant

Question

    ObjectMapper mapper = new ObjectMapper()
            .registerModule(new JavaTimeModule());

    ResteasyClient client = new ResteasyClientBuilder()
            .register(mapper)
            .build();
    ResteasyWebTarget target = client.target(UriBuilder.fromPath(SERVICE_URL + "/api"));

错误：

无法构造java.time.instant的实例：找不到合适的构造函数，无法从对象值反序列化（缺少默认构造函数或创建者，或者可能需要添加/启用类型信息？）

修改Rest服务器以正确序列化Instant类后（例如：“FromTime”：1525681860）

    ObjectMapper deserializer = new ObjectMapper()
            .registerModule(new JavaTimeModule());

    Instant probe = deserializer.readValue("1525681860", Instant.class);
    System.out.println(probe);

因此，结论是RestEasyClient没有注册模块。我肯定做错了什么。

Answer 1

您可以为ObjectMapper定义ContextResolver:

public class ObjectMapperContextResolver implements ContextResolver<ObjectMapper> {

    private final ObjectMapper mapper;

    public ObjectMapperContextResolver() {
        this.mapper = createObjectMapper();
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return mapper;
    }

    private ObjectMapper createObjectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.registerModule(new JavaTimeModule());
        mapper.disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS);
        return mapper;
    }
}

然后在客户端实例中注册解析器：

ResteasyClient client = new ResteasyClientBuilder()
    .register(ObjectMapperContextResolver.class).build();

或者，您可以注册JacksonJsonProvider的实例。该类是JAX-RS抽象(MessageBodyReader和MessageBodyWriter)的基本实现，这些抽象是将JSON内容绑定到Java对象和从Java对象绑定JSON内容所需的。