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Java > Open Source Codes > javax > emb > MediaHeader


1 /*
2  * JBoss, the OpenSource J2EE webOS
3  *
4  * Distributable under LGPL license. See terms of license at gnu.org.
5  */
6
7 package javax.emb;
8
9 import java.io.Serializable;
10
11 /**
12  * The interface MediaHeader defines the common behavior between media header
13  * implementations. All media header instances must allow access to the format
14  * specific header fields by name, in order to allow easy generic access in
15  * case some information is required for browsing purposes. Additionally, all
16  * header fields accessible by the <code>MediaHeader.getField(String)</code>
17  * method must be accessible by standard getter methods, too. As media header
18  * instances have to be transferred over machine boundaries at times, this
19  * interface extends {@link java.io.Serializable}.
20  *
21  * @version <tt>$Revision: 1.4 $</tt>
22  * @author <a HREF="mailto:ricardoarguello@users.sourceforge.net">Ricardo
23  * Argüello</a>
24  */
25 public interface MediaHeader extends Serializable
26 {
27    /**
28     * Returns an array of Strings containing all the field names defined for
29     * the header.
30     *
31     * @return an array of header field names.
32     */
33    String[] getFieldNames();
34
35    /**
36     * Returns the field with the given name downcast to
37     * {@link java.lang.Object}. If the field is modeled as a Java base type,
38     * an instance of the corresponding wrapper class has to be returned. The
39     * value <code>null</code> is returned if a field name is passed that is
40     * not defined for the receiver.
41     *
42     * @param fieldName header field name.
43     * @return the content of a header field.
44     * @throws java.lang.NullPointerException if the value passed is <code>null</code>.
45     */
46    Object getField(String fieldName);
47 }
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