java - bean 类 [java.util.ArrayList] : Bean property `xyz` is not readable or has an invalid getter method 的属性 'xyz' 无效

Question

我是 Spring 启动新手。我在基于 javax 的验证方面遇到问题。 Controller 需要来自 POST 端点的 json obj 列表。在JSON请求json数组中，如果engine或name为 null，我得到正确的 400 错误。但是，当 engine.type或engine.name为 null，它会抛出 500 异常并显示错误消息:

Caused by: org.springframework.beans.NotReadablePropertyException: Invalid property 'engine' of bean class 
[java.util.ArrayList]: Bean property 'engine' is not readable or has an invalid 
getter method: Does the return type of the getter match the parameter type of 
the setter?

Controller .java

@RestController
@Validated
public class CarController {
  @PostMapping(path = "/cars")
  public ResponseEntity<PostModelResponse> createModel(
          @Valid @RequestBody ArrayList<Car> cars)
          throws JSONException, ConstraintViolationException {
          ...
      return new ResponseEntity<>(response, HttpStatus.CREATED);
  }
}

汽车.java

class Car {
  @NotNull
  @Valid
  private Engine engine;

  @NotNull
  private String name;

  Cars(Engine engine, String name) {
    this.engine = engine;
    this.name = name;
  }

  public String getName(){ return name; }
  public void setName(String name) { this.name = name;}
  public Engine getEngine() { return engine; }
  public void setEngine(Engine engine){ this.engine = engine; }

}

引擎.java

class Engine {
  @NotNull
  private String type;
  @NotNull
  private String name;

  Engine(String type, String name) {
    this.type = type;
    this.name = name;
  }
  public String getType() { return type; }
  public void setType(String type) { this.type = type; }
  public String getName() { return name; }
  public void setName(String name) { this.name = name;}
}

CollectionValidator.java

public class CollectionValidator implements Validator {

    private final Validator validator;

    public CollectionValidator(LocalValidatorFactoryBean validator) {
        this.validator = validator;
    }

    @Override
    public boolean supports(Class<?> clazz) {
        return Collection.class.isAssignableFrom(clazz);
    }

    @Override
    public void validate(Object target, Errors errors) {
        Collection col = (Collection) target;
        for ( Object obj : col ) {
            ValidationUtils.invokeValidator(validator, obj, errors);
        }
    }
}

ValidatorAdvice.java

@ControllerAdvice
public class ValidatorAdvice {

    @Autowired
    protected LocalValidatorFactoryBean validator;

    @InitBinder
    public void initBinder(WebDataBinder binder) {
        binder.initDirectFieldAccess();
        binder.addValidators(new CollectionValidator(validator));
    }
}

请求/响应:URL:http://localhost:8080/cars

1. 发布正文:[{“名称”:“沃尔沃”，“引擎” : { “类型”:“v3”， “名称”:“沃尔沃发动机”}}]

   响应:200(好的)

2. 发布正文:[{“引擎” : { “类型”:“v3”， “名称”:“沃尔沃发动机”}}]

   响应:400(这是预期的，因为缺少 name)

3. POST 正文:[{"name": "Volvo"}]

   响应:400(这是预期的，因为缺少 engine)

4. 发布正文:[{“名称”:“沃尔沃”，“引擎” : { “名称”:“沃尔沃发动机”}}]

   响应:500(我期待 400)，错误:

   引起:org.springframework.beans.NotReadablePropertyException:bean类的无效属性“engine” [java.util.ArrayList]:Bean 属性“id”不可读或无效 getter方法:getter的返回类型与参数类型是否匹配 设置者？

在发布此内容之前，我查看了其他 stackOverflow 结果。如果我接受 Car 一切都会正常对象而不是 ArrayList<Car>

非常感谢任何帮助。

Answer 1

validator 在 bean 上工作，而不是列表；一种可能的解决方案是将列表包装在一个 bean 中，并在列表属性上使用 @Valid 注释:

public class MyList<E> {

    @Valid
    private List<E> list;

    public List<E> getList() {
        return list;
    }

    public void setList(List<E> list) {
        this.list = list;
    }
}

并在 Controller 中进行验证:

createModel(@Valid @RequestBody MyList<Car> cars)