检查注解类型@transient

Question

I want to skip fields annotadet with @transient in a query builder.

Something like

if(!fcol.annotationType().equals(@Transient){ do something }

somebody have any idea?

Answer 1

Reflections reflections = new Reflections(packageName);
reflections.getFieldsAnnotatedWith(javax.persistence.Transient.class))

Answer 2

You can check whether the field has the annotation using the following method on the field (assuming your fcol is of type java.lang.reflect.Field):

   /**
     * Returns this element's annotation for the specified type if
     * such an annotation is <em>present</em>, else null.
     *
     * @param <T> the type of the annotation to query for and return if present
     * @param annotationClass the Class object corresponding to the
     *        annotation type
     * @return this element's annotation for the specified annotation type if
     *     present on this element, else null
     * @throws NullPointerException if the given annotation class is null
     * @since 1.5
     */
    <T extends Annotation> T getAnnotation(Class<T> annotationClass);

An example of using the field would be:

if (fcol.getAnnotation(Transient.class) != null)) {
    // do something
}

Answer 3

Assume myObject is an instance of the Entity. You have to iterate over all the fields of the class and check if there are fields annotated with @Transient. If this call return null then it means the field is not annotated with this annotation. So you can do whatever you like:

Field[] fields = myObject.getClass().getFields();
for (Field field : fields) {
    Transient transientAnnoation = field.getAnnotation(Transient.class);
    if (transientAnnoation  == null) {
        do something
    }
 }

Answer 4

Field[] fields = myObject.getClass().getFields();
  for (Field field : fields) {
    boolean isTransient =   
        field.getDeclaredAnnotation(javax.persistence.Transient.class) 
        == null ? false : true;
  }