Spring Boot如何定义接收超类子类实例列表的REST API接口

1. 配置抽象父类的Jackson多态反序列化规则 #

SuperObject是抽象类，默认情况下Jackson无法判断反序列化时应该实例化哪个子类，需要通过注解明确多态识别规则：

@Data
@SuperBuilder
@NoArgsConstructor
@Validated
// 配置多态识别字段：每个JSON对象通过type字段区分子类类型
@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")
// 配置子类和type取值的映射关系
@JsonSubTypes({
        @JsonSubTypes.Type(value = SubType1OfSuperObject.class, name = "sub1"),
        @JsonSubTypes.Type(value = SubType2OfSuperObject.class, name = "sub2")
})
public abstract class SuperObject  {
    private Integer prop1;
    private String prop2;
}

每个请求体中的JSON对象必须携带type字段，取值对应注解中配置的name值，Jackson会自动根据该字段反序列化为对应子类实例

2. 修正接口参数错误 #

你当前接口的参数名拼写有误，先修正：

@PostMapping(path = "store", consumes = MediaType.APPLICATION_JSON_VALUE, produces = MediaType.APPLICATION_JSON_VALUE)
@ResponseStatus(HttpStatus.OK)
@ResponseBody
public String store(@RequestBody List<? extends SuperObject> objects, @RequestParam Technology technology) {
    theService.saveObjectsByTechnology(objects, technology);
    return "Perfect!";
}

3. 调整Postman请求格式 #

你当前接口直接接收List类型的请求体，不需要外层包裹对象，请求体直接传数组即可：

[
  {
    "type": "sub1",
    "prop1": 4,
    "prop2": "foo",
    "prop3": "xxx"
  },
  {
    "type": "sub1",
    "prop1": 7,
    "prop2": "Bar",
    "prop3": "zzz"
  },
  {
    "type": "sub2",
    "prop1": 10,
    "prop2": "test",
    "prop4": "SubType2专属字段"
  }
]

如果确实需要保留外层包裹对象的请求格式，需要单独定义封装类：

@Data
public class SuperObjectRequest {
    private List<? extends SuperObject> subtype1OfSuperObjects;
}

再将接口的@RequestBody参数类型改为SuperObjectRequest即可。

内容的提问来源于stack exchange，提问作者du-it