一個很好用的注解工具類

package com.easyway.commons.ispace.dev.advances.dbmeta;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.*;

public abstract class AnnotationUtils
{

    public AnnotationUtils()
    {
    }
   /**
    * 擷取一個方法的所有注解
    * @param method
    * @return
    */
    public static Annotation[] getAnnotations(Method method)
    {
    	
    	 return method.getAnnotations();
    }
    /**
     * 擷取方法的一個注解類型
     * @param method
     * @param annotationType
     * @return
     */
    public static Annotation getAnnotation(Method method, Class annotationType)
    {
    	return method.getAnnotation(annotationType);
    }
    
   /**
    * 查找一個方法的注解類型
    * @param method
    * @param annotationType
    * @return
    */
    public static Annotation findAnnotation(Method method, Class annotationType)
    {
        Annotation annotation = getAnnotation(method, annotationType);
        Class cl = method.getDeclaringClass();
        do
        {
            if(annotation != null)
                break;
            cl = cl.getSuperclass();
            if(cl == null || cl.equals(Object.class))
                break;
            try
            {
                Method equivalentMethod = cl.getDeclaredMethod(method.getName(), method.getParameterTypes());
                annotation = getAnnotation(equivalentMethod, annotationType);
            }
            catch(NoSuchMethodException ex) { }
        } while(true);
        return annotation;
    }
    /**
     * 查找一個類的某種注解類型
     * @param clazz
     * @param annotationType
     * @return
     */
    public static Annotation findAnnotation(Class clazz, Class annotationType)
    {
        Annotation annotation = clazz.getAnnotation(annotationType);
        if(annotation != null)
            return annotation;
        Class clazzes[] = clazz.getInterfaces();
        int len = clazzes.length;
        for(int i = 0; i < len; i++)
        {
            Class ifc = clazzes[i];
            annotation = findAnnotation(ifc, annotationType);
            if(annotation != null)
                return annotation;
        }

        if(clazz.getSuperclass() == null || Object.class.equals(clazz.getSuperclass()))
            return null;
        else
            return findAnnotation(clazz.getSuperclass(), annotationType);
    }
    /**
     * 查找包含某種注解類型的Class類型的Class
     * @param annotationType
     * @param clazz
     * @return
     */
    public static Class findAnnotationDeclaringClass(Class annotationType, Class clazz)
    {
        if(clazz == null || clazz.equals(Object.class))
            return null;
        else
            return isAnnotationDeclaredLocally(annotationType, clazz) ? clazz : findAnnotationDeclaringClass(annotationType, clazz.getSuperclass());
    }
    /**
     * 檢查一個類是否包含一個特定的注解類型
     * @param annotationType
     * @param clazz
     * @return
     */
    public static boolean isAnnotationDeclaredLocally(Class annotationType, Class clazz)
    {
        boolean declaredLocally = false;
        Iterator i$ = Arrays.asList(clazz.getDeclaredAnnotations()).iterator();
        do
        {
            if(!i$.hasNext())
                break;
            Annotation annotation = (Annotation)i$.next();
            if(!annotation.annotationType().equals(annotationType))
                continue;
            declaredLocally = true;
            break;
        } while(true);
        return declaredLocally;
    }

    public static boolean isAnnotationInherited(Class annotationType, Class clazz)
    {
        return clazz.isAnnotationPresent(annotationType) && !isAnnotationDeclaredLocally(annotationType, clazz);
    }

    /**
     * 擷取注解所有的屬性
     * @param annotation
     * @return
     */
    public static Map getAnnotationAttributes(Annotation annotation)
    {
        Map attrs = new HashMap();
        Method methods[] = annotation.annotationType().getDeclaredMethods();
        for(int j = 0; j < methods.length; j++)
        {
            Method method = methods[j];
            if(method.getParameterTypes().length != 0 || method.getReturnType() == Void.TYPE)
                continue;
            try
            {
                attrs.put(method.getName(), method.invoke(annotation, new Object[0]));
            }
            catch(Exception ex)
            {
                throw new IllegalStateException("Could not obtain annotation attribute values", ex);
            }
        }

        return attrs;
    }

    public static Object getValue(Annotation annotation)
    {
        return getValue(annotation, "value");
    }
    /**
     * 擷取注解對應的屬性值
     * @param annotation
     * @param attributeName
     * @return
     */
    public static Object getValue(Annotation annotation, String attributeName)
    {
        try
        {
            Method method = annotation.annotationType().getDeclaredMethod(attributeName, new Class[0]);
            return method.invoke(annotation, new Object[0]);
        }
        catch(Exception ex)
        {
            return null;
        }
    }

    public static Object getDefaultValue(Annotation annotation)
    {
        return getDefaultValue(annotation, "value");
    }

    public static Object getDefaultValue(Annotation annotation, String attributeName)
    {
        return getDefaultValue(annotation.annotationType(), attributeName);
    }

    public static Object getDefaultValue(Class annotationType)
    {
        return getDefaultValue(annotationType, "value");
    }

    public static Object getDefaultValue(Class annotationType, String attributeName)
    {
        try
        {
            Method method = annotationType.getDeclaredMethod(attributeName, new Class[0]);
            return method.getDefaultValue();
        }
        catch(Exception ex)
        {
            return null;
        }
    }

    static final String VALUE = "value";
}