/*
* Copyright 2002-2015 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.messaging.handler.annotation;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.core.annotation.AliasFor;
/**
* Annotation which indicates that a method parameter should be bound to a message header.
*
* @author Rossen Stoyanchev
* @author Sam Brannen
* @since 4.0
*/
@Target(ElementType.PARAMETER)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Header {
/**
* Alias for {@link #name}.
*/
@AliasFor("name")
String value() default "";
/**
* The name of the request header to bind to.
* @since 4.2
*/
@AliasFor("value")
String name() default "";
/**
* Whether the header is required.
* <p>Default is {@code true}, leading to an exception if the header is
* missing. Switch this to {@code false} if you prefer a {@code null}
* value in case of a header missing.
* @see #defaultValue
*/
boolean required() default true;
/**
* The default value to use as a fallback.
* <p>Supplying a default value implicitly sets {@link #required} to {@code false}.
*/
String defaultValue() default ValueConstants.DEFAULT_NONE;
}