AnnotationFormatterFactory.java

/*
 * Copyright 2002-2009 the original author or authors.
 *
 * Licensed 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.springframework.format;

import java.lang.annotation.Annotation;
import java.util.Set;

/**
 * A factory that creates formatters to format values of fields annotated with a particular {@link Annotation}.
 *
 * <p>For example, a <code>DateTimeFormatAnnotationFormatterFactory</code> might create a formatter
 * that formats <code>Date</code> values set on fields annotated with <code>@DateTimeFormat</code>.
 *
 * @author Keith Donald
 * @since 3.0 
 * @param <A> the annotation type that should trigger formatting
 */
public interface AnnotationFormatterFactory<A extends Annotation> {

	/**
	 * The types of fields that may be annotated with the <A> annotation.
	 */
	Set<Class<?>> getFieldTypes();

	/**
	 * Get the Printer to print the value of a field of <code>fieldType</code> annotated with <code>annotation</code>.
	 * If the type <T> the printer accepts is not assignable to <code>fieldType</code>, a coersion from <code>fieldType</code> to <T> will be attempted before the Printer is invoked.
	 * @param annotation the annotation instance
	 * @param fieldType the type of field that was annotated
	 * @return the printer
	 */
	Printer<?> getPrinter(A annotation, Class<?> fieldType);

	/**
	 * Get the Parser to parse a submitted value for a field of <code>fieldType</code> annotated with <code>annotation</code>.
	 * If the object the parser returns is not assignable to <code>fieldType</code>, a coersion to <code>fieldType</code> will be attempted before the field is set.
	 * @param annotation the annotation instance
	 * @param fieldType the type of field that was annotated
	 * @return the parser
	 */
	Parser<?> getParser(A annotation, Class<?> fieldType);
	
}