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1   /*
2    * $Id: InboundHeaders.java 18452 2010-07-21 19:15:38Z aperepel $
3    * --------------------------------------------------------------------------------------
4    * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
5    *
6    * The software in this package is published under the terms of the CPAL v1.0
7    * license, a copy of which has been included with this distribution in the
8    * LICENSE.txt file.
9    */
10  
11  package org.mule.api.annotations.param;
12  
13  import org.mule.api.annotations.meta.Evaluator;
14  
15  import java.lang.annotation.Documented;
16  import java.lang.annotation.ElementType;
17  import java.lang.annotation.Retention;
18  import java.lang.annotation.RetentionPolicy;
19  import java.lang.annotation.Target;
20  
21  /**
22   * Used on component methods, this annotation marks the method parameter that will be used to pass in one or more of the headers received.
23   * This annotation value can define a single header, a comma-separated list of header names, '*' to denote all headers, or a comma-separated list
24   * of wildcard expressions such as 'MULE_*, X-*'. By default, if a named header is not present on the current message, an exception will be thrown.
25   * However, if the header name is defined with the '?' post fix, it will be marked as optional.
26   * <p/>
27   * When defining multiple header names or using wildcards, the parameter can be a {@link java.util.Map} or {@link java.util.List}. If a
28   * {@link java.util.Map} is used, the header name and value is passed in. If {@link java.util.List} is used, just the header values are used.
29   * If a single header name is defined, the header type can be used as the parameter type, though {@link java.util.List} or {@link java.util.Map}
30   * can be used too.
31   *
32   * The Inbound headers collection is immutable, so the headers Map or List passed in will be immutable too. Attempting to write to the Map or List will result in an {@link UnsupportedOperationException}.
33   */
34  @Target(ElementType.PARAMETER)
35  @Retention(RetentionPolicy.RUNTIME)
36  @Documented
37  @Evaluator("messageProperty")
38  public @interface InboundHeaders
39  {
40      /**
41       * Defines the headers that should be injected into the parameter. This can be a single header, a comma-separated
42       * list of header names,'*' to denote all headers or a comma-separated list of wildcard expressions. By default,
43       * if a named header is not present, an exception will be thrown. However, if the header name is defined with the
44       * '?' post fix, it will be marked as optional.
45       * The optional '?' post fix is not supported when using wildcard expressions
46       *
47       * @return the header expression used to query the message for headers
48       */
49       String value();
50  }