001// Copyright 2006, 2009, 2010 The Apache Software Foundation 002// 003// Licensed under the Apache License, Version 2.0 (the "License"); 004// you may not use this file except in compliance with the License. 005// You may obtain a copy of the License at 006// 007// http://www.apache.org/licenses/LICENSE-2.0 008// 009// Unless required by applicable law or agreed to in writing, software 010// distributed under the License is distributed on an "AS IS" BASIS, 011// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 012// See the License for the specific language governing permissions and 013// limitations under the License. 014 015package org.apache.tapestry5.annotations; 016 017import static java.lang.annotation.ElementType.FIELD; 018import static java.lang.annotation.RetentionPolicy.RUNTIME; 019import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.COMPONENT; 020import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.MIXIN; 021import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.PAGE; 022 023import java.lang.annotation.Documented; 024import java.lang.annotation.Retention; 025import java.lang.annotation.Target; 026 027import org.apache.tapestry5.ioc.annotations.UseWith; 028import org.apache.tapestry5.services.javascript.JavaScriptSupport; 029 030/** 031 * Defines a field of a component class that is replaced at runtime with a read-only value obtained from the 032 * {@link org.apache.tapestry5.services.Environment} service. 033 * <p> 034 * Most commonly, the field will be of type {@link JavaScriptSupport}, {@link org.apache.tapestry5.services.Heartbeat} 035 * or {@link org.apache.tapestry5.services.FormSupport}, though many other options are possible. 036 */ 037@Target(FIELD) 038@Documented 039@Retention(RUNTIME) 040@UseWith( 041{ COMPONENT, MIXIN, PAGE }) 042public @interface Environmental 043{ 044 /** 045 * The value determines if the environmental service to be injected is required or not. In most cases, it is, so the 046 * default is true. 047 */ 048 boolean value() default true; 049}