001 /****************************************************************
002 * Licensed to the Apache Software Foundation (ASF) under one *
003 * or more contributor license agreements. See the NOTICE file *
004 * distributed with this work for additional information *
005 * regarding copyright ownership. The ASF licenses this file *
006 * to you under the Apache License, Version 2.0 (the *
007 * "License"); you may not use this file except in compliance *
008 * with the License. You may obtain a copy of the License at *
009 * *
010 * http://www.apache.org/licenses/LICENSE-2.0 *
011 * *
012 * Unless required by applicable law or agreed to in writing, *
013 * software distributed under the License is distributed on an *
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY *
015 * KIND, either express or implied. See the License for the *
016 * specific language governing permissions and limitations *
017 * under the License. *
018 ****************************************************************/
019
020 package org.apache.james.mime4j.dom;
021
022 import java.util.Iterator;
023 import java.util.List;
024
025 import org.apache.james.mime4j.stream.Field;
026
027 /**
028 * A header of an MIME entity (as defined in RFC 2045).
029 */
030 public interface Header extends Iterable<Field> {
031
032 /**
033 * Adds a field to the end of the list of fields.
034 *
035 * @param field the field to add.
036 */
037 void addField(Field field);
038
039 /**
040 * Gets the fields of this header. The returned list will not be
041 * modifiable.
042 *
043 * @return the list of <code>Field</code> objects.
044 */
045 List<Field> getFields();
046
047 /**
048 * Gets a <code>Field</code> given a field name. If there are multiple
049 * such fields defined in this header the first one will be returned.
050 *
051 * @param name the field name (e.g. From, Subject).
052 * @return the field or <code>null</code> if none found.
053 */
054 Field getField(String name);
055
056 /**
057 * Gets all <code>Field</code>s having the specified field name.
058 *
059 * @param name the field name (e.g. From, Subject).
060 * @return the list of fields.
061 */
062 List<Field> getFields(final String name);
063
064 /**
065 * Returns an iterator over the list of fields of this header.
066 *
067 * @return an iterator.
068 */
069 Iterator<Field> iterator();
070
071 /**
072 * Removes all <code>Field</code>s having the specified field name.
073 *
074 * @param name
075 * the field name (e.g. From, Subject).
076 * @return number of fields removed.
077 */
078 int removeFields(String name);
079
080 /**
081 * Sets or replaces a field. This method is useful for header fields such as
082 * Subject or Message-ID that should not occur more than once in a message.
083 *
084 * If this <code>Header</code> does not already contain a header field of
085 * the same name as the given field then it is added to the end of the list
086 * of fields (same behavior as {@link #addField(Field)}). Otherwise the
087 * first occurrence of a field with the same name is replaced by the given
088 * field and all further occurrences are removed.
089 *
090 * @param field the field to set.
091 */
092 void setField(Field field);
093
094 }