自定义注释不适用于嵌套对象字段

Question

我创建了用于验证的小型自定义注释。如果该字段使用自定义注解进行注解，则会抛出异常。

下面是代码

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Retention(RetentionPolicy.RUNTIME)
@Target({ ElementType.FIELD})
public @interface NotRequired {
    public boolean value() default true;
}

型号::

public class Profile implements IProfile{
    @NotRequired
    private Integer id; 
    private String fName;    
    private IAddress add;
  //setter and getter

public class Address implements IAddress{
    @NotRequired
    private String address;

测试类::

public class CustomAnnotationTest {

    public static void main(String[] args) {
        IProfile profile = new Profile();      
        //profile.setId(123);  // in this case it is working fine
        IAddress address= new Address();
        address.setAddress("Aus"); // not working, expected exception should be thrown
        profile.setAdd(address);
        try {
            if (CustomAnnotationNotRequired.validateForNotRequirdField(profile)) {
               System.out.println("Validation Successful");
            }
        } catch (Exception e) {        
            e.printStackTrace();
        }
    }
}

验证器类：

public class CustomAnnotationNotRequired {
    public static boolean validateForNotRequirdField(Object objectToValidate)
            throws Exception {

        Field[] declaredFields = objectToValidate.getClass().getDeclaredFields();

        for(Field field : declaredFields) {

            Annotation annotation = field.getAnnotation(NotRequired.class);

            if (annotation != null) {

                NotRequired notRequired = (NotRequired) annotation;

                if (notRequired.value()) {
                     field.setAccessible(true); 
                     // annotated field is having value 
                     if (field.get(objectToValidate) != null) {
                         throw new Exception();
                     }
                }
            }
        }
        return true;
    }
}

测试用例： 1)

 IProfile profile = new Profile();     
        profile.setId(123); 

// 这个输入得到正确的结果

2)

IProfile profile = new Profile();      
            //profile.setId(123);
            IAddress address= new Address();
            address.setAddress("Aus");
            profile.setAdd(address);  

// 预期异常。Address 类的字段使用@NotRequired 注释进行了注释，但没有给出正确的结果。

Answer 1

验证不适用于address 字段，因为validateForNotRequirdField 方法仅验证profile 的字段，而不检查Address 的@NotRequired 注释。假设@NotRequired 只应用于一些常见的值类，对validateForNotRequirdField 方法的以下更改将产生预期的结果。

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.math.BigDecimal;
import java.util.Date;

public class CustomAnnotationNotRequired {
  public static boolean validateForNotRequirdField(Object objectToValidate)
      throws Exception {

    Field[] declaredFields = objectToValidate.getClass().getDeclaredFields();

    for (Field field : declaredFields) {

      Annotation annotation = field.getAnnotation(NotRequired.class);
      if (!isValueClass(field.getType())) {
        field.setAccessible(true);
        if (field.get(objectToValidate) != null) {
          // validate nested field
          validateForNotRequirdField(field.get(objectToValidate));
        }
        continue;
      }
      if (annotation != null) {

        NotRequired notRequired = (NotRequired) annotation;

        if (notRequired.value()) {
          field.setAccessible(true);
          // annotated field is having value
          if (field.get(objectToValidate) != null) {
            throw new Exception();
          }
        }
      }
    }
    return true;
  }

  private static boolean isValueClass(Class<?> fieldType) {
    // Add other class if needed.
    return fieldType.equals(String.class) || fieldType.equals(Integer.class)
           || fieldType.equals(Short.class) || fieldType.equals(Long.class)
           || fieldType.equals(BigDecimal.class)
           || fieldType.equals(Date.class);
  }
}