反射根据annotation实现一些功能

  public void initGetter(ActionInvocation invocation) {
    HttpServletRequest request = ServletActionContext.getRequest();
    Class actionClass = invocation.getAction().getClass();
    Field[] fields = actionClass.getDeclaredFields();
    for (Field field : fields) {
      Annotation[] annotations = field.getDeclaredAnnotations();
      for (Annotation annotation : annotations)
        if (annotation instanceof GetterAndSetter) {
          GetterAndSetter getterAndSetter = (GetterAndSetter)annotation;
          field.setAccessible(true);
          try {
            Object value = field.get(invocation.getAction());
            request.setAttribute(field.getName(), value);
          } catch (Exception e) {
            e.printStackTrace();
          }
        }
    }
  }

例子2:
/**
 * 
 */
package annotation;

import java.lang.annotation.Annotation;

import annotation.FirstTag.ALLNAME;

/**
 * @author Qianmz
 * @date Mar 26, 2010/11:10:56 PM
 */
public class TagClazz {
	
	@FirstTag(name="Qianmz",id=1000,lastName=ALLNAME.ZHAO)
	public void doExecute(){
		
	}
	
	public static void main(String[] args) {
		TagClazz tc = new TagClazz();
		try {
			Annotation[] ann = 
				tc.getClass().getMethod("doExecute").getAnnotations();
			for(Annotation an : ann){
				System.out.println(an.getClass());
				System.out.println(an.annotationType());
				System.out.println(((FirstTag)an).name());
				System.out.println(((FirstTag)an).id());
				System.out.println(((FirstTag)an).lastName());
			}
		} catch (SecurityException e) {
			e.printStackTrace();
		} catch (NoSuchMethodException e) {
			e.printStackTrace();
		}
	}
}
================================
result:
interface annotation.FirstTag
Qianmz
1000
ZHAO