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如何将@RestController中的请求体转换为抽象值列表?

spring-restcontroller spring-mvc spring java

dukethrash · 技术社区 · 6 年前

假设我们有以下课程:

public abstract class Investment {

   private String investmentType;

   // getters & setters
}

public class Equity extends Investment {
}

public class Bond extends Investment {
}

public class InvestmentFactory {

    public static Investment getTypeFromString(String investmentType) {
        Investment investment = null;
        if ("Bond".equals(investmentType)) {
            investment = new Bond();
        } else if ("Equity".equals(investmentType)) {
            investment = new Equity();
        } else {
            // throw exception
        }
        return investment;
    }
}

@RestController :

@RestController
public class InvestmentsRestController {

    private InvestmentRepository investmentRepository;

    @Autowired
    public InvestmentsRestController(InvestmentRepository investmentRepository) {
        this.investmentRepository = investmentRepository;
    }

    @RequestMapping(RequestMethod.POST)
    public List<Investment> update(@RequestBody List<Investment> investments) {
       return investmentRepository.update(investments);
    }

}

以及请求正文中的以下json:

[
  {"investmentType":"Bond"},
  {"investmentType":"Equity"}
]

List<Investment> 不用杰克逊的 @JsonSubTypes 论抽象类 Investment ,而使用 InvestmentFactory

2 回复 | 直到 6 年前

Joe A 6 年前

@JsonDeserialize工作得很好,但是如果您有比类型更多的字段,那么您将不得不手动设置它们。如果你要回到杰克逊,你可以使用:

投资类

    @JsonTypeInfo(
            use = JsonTypeInfo.Id.NAME,
            include = JsonTypeInfo.As.PROPERTY,
            property = "investmentType")
    @JsonTypeIdResolver(InvestmentResolver.class)
    public abstract class Investment {
    }

public class InvestmentResolver extends TypeIdResolverBase {

    @Override
    public JavaType typeFromId(DatabindContext context, String id) throws IOException {
        Investment investment = InvestmentFactory.getTypeFromString(type);
        return context.constructType(investment.getClass());
    }

这样做的好处是,如果你开始在投资中添加字段,你就不必在Desrializer中添加字段(至少,在我的情况下,这种情况发生在我身上),而是Jackson会为你处理它。所以明天你就可以得到测试用例了:

'[{"investmentType":"Bond","investmentName":"ABC"},{"investmentType":"Equity","investmentName":"APPL"}]'

Denis Zavedeev Brian Kelly 6 年前

@JsonDeserialize

@JsonDeserialize(using = InvestmentDeserializer.class)
public abstract class Investment {
}



public class InvestmentDeserializer extends JsonDeserializer<Investment> {
    @Override
    public Investment deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {
        ObjectMapper objectMapper = (ObjectMapper) p.getCodec();
        TreeNode node = objectMapper.readTree(p);

        TreeNode investmentNode = node.get("investmentType");
        String type = objectMapper.readValue(investmentNode.traverse(objectMapper), String.class);
        return InvestmentFactory.getTypeFromString(type);
    }
}

@RestController
public class MyController {
    @RequestMapping("/")
    public List<Class<?>> update(@RequestBody List<Investment> investments) {
        return investments.stream().map(Object::getClass).collect(Collectors.toList());
    }
}

测试:

$ curl localhost:8080 -H "Content-Type: application/json" -d '[{"investmentType":"Bond"},{"investmentType":"Equity"}]'

输出:

["com.example.demo.Bond","com.example.demo.Equity"]