@NotEmpty、@NotNull、@NotBlank 的區別，Boolean類型入參用什麼註解

@NotEmpty 用在集合上面(不能註釋枚舉)

@NotBlank用在String上面

@NotNull用在所有類型上面

1. @NotEmpty Asserts that the annotated string, collection, map or array is not {@code null} or empty. 加了@NotEmpty的String類，Collection、Map、數組，是不能爲null或者長度爲0的（String、Collection、Map 的isEmpth()方法）

2. @NotBlank Validate that the annotated string is not {@code null} or empty. The difference to {@code NotEmpty} is that trailing whitespaces are getting ignored. “The difference to {@code NotEmpty} is that trailing whitespaces are getting ignored.” –> 和{@code NotEmpty}不同的是，尾部空格被忽略，也就是說，純空格的String也是不符合規則的。所以纔會說@NotBlank用於String。

3.NotNull The annotated element must not be {@code null}. Accepts any type. 這個就很好理解了，不能爲null。

Boolean類型的參數使用NotNull註解。

參考自：https://www.cnblogs.com/huahua035/p/8358202.html

 

實際應用：

entity：

public class CreateUserRequest {

    @NotEmpty(message = "Missing Mandatory Field")
    @Length(max = 8, message = "Username length cannot exceed 8 characters")
    private String username;



    @NotNull
    @JsonProperty("internal_user")
    private Boolean internalUser;

}

接口：

@PostMapping(value = "/users", produces = MediaType.APPLICATION_JSON_VALUE)
 public BaseSuccessResponse addUser(@Valid @RequestBody CreateUserRequest addUserRequest, BindingResult bindingResult) throws Exception, UnsupportedEncodingException {
        CommonUtils.parameterChecking(bindingResult);       
        return userService.addUser(addUserRequest);
    }

注意添加：@Valid

工具類：

public class CommonUtils { 
public static void parameterChecking(BindingResult bindingResult) throws Exception {
        if (bindingResult.hasErrors()) {
            List<FieldError> listError = bindingResult.getFieldErrors();
            Set<String> parameters = new HashSet<>();
            Iterator keys = listError.iterator();
            FieldError iterator = null;
            while (keys.hasNext()) {
                iterator = (FieldError) keys.next();
                String field = iterator.getField();
                parameters.add(field);
            }
            if (iterator != null) {
                throw new Exception(Error.getErrorByMsg(iterator.getDefaultMessage()), parameters);
            }
        }
    }
}

//再定義Error.class.....