复合多态类型的Spring REST JSON序列化/反序列化

Question

我将Spring / Spring Boot和Spring MVC与@RestController一起使用

我有一个复合模型对象：

public abstract class BaseQuery {

    private final Long characteristicId;

...

}

public abstract class ComparableQuery extends BaseQuery {

    private final Object value;

    private final String comparisonOperator;

...

}

public class GreaterOrEqualQuery extends ComparableQuery {

    public GreaterOrEqualQuery(Long characteristicId, Object value) {
        super(characteristicId, value, ">=");
    }

}

public class EqualQuery extends ComparableQuery {

    public EqualQuery(Long characteristicId, Object value) {
        super(characteristicId, value, "=");
    }

}

public class GreaterQuery extends ComparableQuery {

    public GreaterQuery(Long characteristicId, Object value) {
        super(characteristicId, value, ">");
    }

}

public class CompositQuery extends BaseQuery {

    private final String operator;
    private final BaseQuery[] queries;

    public CompositQuery(Long characteristicId, Operator operator, BaseQuery... queries) {
        super(characteristicId);
        this.operator = operator.value;
        this.queries = queries;
    }

...

}

等等

该模型的示例用法如下所示：

Set<BaseQuery> queries = new HashSet<>();

BaseQuery megapixelCharacteristicQuery = new CompositQuery(megapixelCharacteristic.getCharacteristicId(), CompositQuery.Operator.AND, new GreaterOrEqualQuery(megapixelCharacteristic.getCharacteristicId(), 10), new LessOrEqualQuery(megapixelCharacteristic.getCharacteristicId(), 50));
queries.add(megapixelCharacteristicQuery);
queries.add(new EqualQuery(androidCharacteristic.getCharacteristicId(), true));

序列化的JSON对象的Set<BaseQuery> queries外观如下：

[
   {
      "operator":"AND",
      "queries":[
         {
            "value":10,
            "comparisonOperator":"\u003e\u003d",
            "characteristicId":391
         },
         {
            "value":50,
            "comparisonOperator":"\u003c\u003d",
            "characteristicId":391
         }
      ],
      "characteristicId":391
   },
   {
      "value":true,
      "comparisonOperator":"\u003d",
      "characteristicId":383
   }
]

我必须将这个或类似的JSON从客户端应用程序（AngularJS）传递到我的后端REST API端点，以便如上所述获得正确的反序列化模型（设置适当的条目，例如CompositQuery或EqualQuery）。

现在，我的Rest控制器上的Spring应用程序后端逻辑无法使用适当的类正确反序列化此JSON。

Spring是否可以通过某种方式向此JSON提供一些元信息（或其他信息），以帮助Spring正确地反序列化此结构？

Answer 1

您可以使用超类上的jackson注释来实现此目的，如下所示：

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonSubTypes;
import com.fasterxml.jackson.annotation.JsonSubTypes.Type;
import com.fasterxml.jackson.annotation.JsonTypeInfo;

@JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "javaclass")
@JsonSubTypes({
    @Type(value = GreaterOrEqualQuery.class),
    @Type(value = EqualQuery.class)
    //and so on...
})
public abstract class BaseQuery {
    ...
}

这会将javaclass属性添加到json表示形式中，在的情况下为完全限定名称use = JsonTypeInfo.Id.CLASS。为了简化此属性的值，请考虑（）use参数的不同选项。@JsonTypeInfoJsonTypeInfo.Id.NAME