反序列化子类型丢失

江喜原2025-03-07 9:01

使用 fastjson 进行序列化

java 复制代码

public class RealTimeMetricData extends RealTimeMetricDataIndex {

    private int version;

    @Nullable
    private Object data;
}

java 复制代码

public class RealTimeMetricDataIndex {
    
    private RealTimeBaseMetric metric;

    private String pk;

    private String binName;
}

objectMapper 配置

java 复制代码

objectMapper.addMixIn(RealTimeBaseMetric.class, RealTimeBaseMetricMixin.class);
//        this.objectMapper = new ObjectMapper().setSerializationInclusion(JsonInclude.Include.NON_NULL)
//                .disable(SerializationFeature.FAIL_ON_EMPTY_BEANS)
//                .disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
//                .activateDefaultTyping(LaissezFaireSubTypeValidator.instance, ObjectMapper.DefaultTyping.JAVA_LANG_OBJECT);
        this.objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

序列化

java 复制代码

objectMapper.writeValueAsString(RealTimeMetricData);

反序列化

java 复制代码

objectMapper.readValue(key, new TypeReference<List<RealTimeMetricData>>() {});

问题：此时反序列化得到的 RealTimeBaseMetric类型丢失

解决：

方法一：使用注解（需修改RealTimeBaseMetric类）：

在RealTimeBaseMetric类上添加Jackson注解：

java 复制代码

@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class")
public abstract class RealTimeBaseMetric {
    // 原有代码
}

方法二：使用Mix-in（无需修改源代码）：

创建Mix-in类：

java 复制代码

@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "@class")
public abstract class RealTimeBaseMetricMixin {}

配置ObjectMapper：

java 复制代码

ObjectMapper objectMapper = new ObjectMapper();
objectMapper.addMixIn(RealTimeBaseMetric.class, RealTimeBaseMetricMixin.class);