无法通过ReflectionUtils.setField设置字段值

Question

I am creating a custom made annotation that sets random int number from the specific interval (min, max).

 @GenerateRandomInt(min=2, max=7)

I have implemented interface BeanPostProcessor . Here is its implementation:

public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {

    Field[] fields=bean.getClass().getFields();
    for (Field field : fields) {
        GenerateRandomInt annotation = field.getAnnotation(GenerateRandomInt.class);

        System.out.println(field.getName());
        if(annotation!=null){


            int min = annotation.min();
            int max = annotation.max();

            Random random = new Random();

            int i = random.nextInt(max-min);
            field.setAccessible(true);
            System.out.println("Field name: "+field.getName()+" value to inject:"+i);
            ReflectionUtils.setField(field,bean,i);
        }
    }

    return bean;
}

Here is the spring context xml config:

<bean class="InjectRandomIntAnnotationBeanPostProcessor"/>
<bean class="Quotes" id="my_quote">
    <property name="quote" value="Hello!"/>
</bean>

However, when I test the program, the value of the desired field is to the 0 (checked 10 times). The code line, that prints the field name and value to be injected doesn't work as well. What might be an error? How is it possible to proper define the field custom made annotation?

PS

Class that uses this annotation:

public class Quotes implements Quoter {

    @GenerateRandomInt(min=2, max=7)
    private int timesToSayHello;

    private String quote;
    public String getQuote() {
        return quote;
    }

    public void setQuote(String quote) {
        this.quote = quote;
    }

    @Override
    public void sayHello() {
        System.out.println(timesToSayHello);
        for (int i=0;i<timesToSayHello;i++) {
            System.out.println("Hello");
        }
    }
}

Interface that describes annotation @GenerateRandomInt

@Retention(RetentionPolicy.RUNTIME)
public @interface GenerateRandomInt {
    int min();
    int max();
}

Answer 1

Instead of getFields use getDeclaredFields .

The first will only give you public fields, the latter gives you all fields.

Another tip: As you are already using ReflectionUtils I suggest using the doWithFields method to simplify your code.

ReflectionUtils.doWithFields(bean.getClass(), 
    new FieldCallback() {
        public void doWith(Field field) throws IllegalArgumentException, IllegalAccessException {
            GenerateRandomInt annotation = field.getAnnotation(GenerateRandomInt.class);
            int min = annotation.min();
            int max = annotation.max();
            int i = random.nextInt(max-min);
            ReflectionUtils.makeAccessible(field);
            ReflectionUtils.setField(bean, field, i);
        }

    }, 
    new FieldFilter() {
        public boolean matches(Field field) {
            return field.getAnnotation(GenerateRandomInt.class) != null;
        }
    });