org.apache.tapestry.ioc.annotations.Inject Maven / Gradle / Ivy

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// Copyright 2006, 2007 The Apache Software Foundation
//
// 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.apache.tapestry.ioc.annotations;

import org.apache.tapestry.ioc.ObjectProvider;

import java.lang.annotation.Documented;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.PARAMETER;
import java.lang.annotation.Retention;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
import java.lang.annotation.Target;

/**
 * This annotation serves two similar purposes: it marks parameters that should be injected in the
 * IoC container, and it marks fields that should be injected inside Tapestry components.
 * 
 * In terms of the IoC container; normally, resources take precedence over annotations when
 * injecting. The Inject annotation overrides this default, forcing the resolution of the parameters
 * value via the master {@link ObjectProvider}, even when the parameter's type matches a type that
 * is normally a resource. This is most often used in conjunction with {@link Value} annotation when
 * injecting a string, as normally, the String would be matched as the service id.
 * 
 * In terms of the IoC container, the Inject annotation is only used on parameters to service
 * builder methods and constructors. However, inside Tapestry components (and only inside components),
 * it may be applied to fields. On fields that require injection, the Inject annotation is
 * required.
 *
 * @see ObjectProvider
 */
@Target(
        {PARAMETER, FIELD})
@Retention(RUNTIME)
@Documented
public @interface Inject
{

}