taverna-beaninfo/src/main/java/org/apache/taverna/lang/beans/PropertyAnnotation.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.taverna.lang.beans;

import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * An annotation of a Java bean style property method, ie. a getXX() or setXX()
 * method.
 * <p>
 * The annotations allow the method to better describe properties such as
 * {@link #displayName()}, {@link #shortDescription()} and {@link #hidden()}.
 * <p>
 * The annotations can be retrieved as {@link PropertyDescriptor} using
 * {@link PropertyAnnotationExtractor}, or if {@link PropertyAnnotated} has been
 * used (recommended), through Java's BeanInfo support, such as using
 * {@link Introspector}.
 * <p>
 * Annotations can be applied to interfaces or classes, abstract and normal 
 * methods, as long as they confirm with the Java bean conventions. Annotations 
 * will be inherited, so overriding methods don't need to reapply the annotations,
 * although they can if they want to override.
 * <p>
 * It is recommended that classes using these annotations either subclass
 * {@link PropertyAnnotated} or have a neighbouring BeanInfo class that
 * subclasses PropertyAnnotated.
 * <p>
 * Example usage:
 * 
 * <pre>
 * 	public interface MyBean {
 *		// Annotation for the property called "name". displayName: Title
 *		// of the property shown in UI instead of "name".
 *		&#064;PropertyAnnotation(displayName = "Full name")
 *		public String getName();
 *
 *		// Second annotation for the write-method of the same property called
 *		// "name". Both displayName and shortDescription will be set on the
 *		// property descriptor.
 *		&#064;PropertyAnnotation(shortDescription = "The name of the person")
 *		public void setName(String name);
 *
 *		// Boolean read method for the property "married", two annotations.
 *		// expert: Only shown in UI under "advanced" views.
 *		&#064;PropertyAnnotation(expert = true, shortDescription = "Marital status")
 *		public boolean isMarried();
 *
 *		// Write-method for the "married" property, no new annotations, but will
 *		// get the ones from {&#064;link #isMarried()}.
 *		public void setMarried(boolean married);
 *
 *		// Write-only method, hidden (not shown in UIs).
 *		&#064;PropertyAnnotation(hidden = true)
 *		public void setID(String id);
 *
 *		// Read-only method, no annotations, defaults will be used.
 *		public void getTelephoneNumber(String number);
 *	}
 * </pre>
 * 
 * @see PropertyAnnotated
 * @author Stian Soiland-Reyes
 * 
 */
@Retention(RetentionPolicy.RUNTIME)
@Target( { ElementType.METHOD })
public @interface PropertyAnnotation {

	/**
	 * A unique string that means the default should be used
	 */
	public static String DEFAULT = "Default_8930B86A-50C0-4859-9B6F-DD034B3C5C1E";

	String displayName() default DEFAULT;

	String name() default DEFAULT;

	String shortDescription() default DEFAULT;

	boolean expert() default false;

	boolean hidden() default false;

	boolean preferred() default false;

}