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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.net.nntp;
19  
20  /**
21   * This class is used to construct the bare minimum acceptable header for most newsreaders. To construct more complicated headers you should refer to RFC 822.
22   * When the Java Mail API is finalized, you will be able to use it to compose fully compliant Internet text messages.
23   * <p>
24   * The main purpose of the class is to faciliatate the article posting process, by relieving the programmer from having to explicitly format an article header.
25   * For example:
26   * </p>
27   *
28   * <pre>
29   * writer = client.postArticle();
30   * if (writer == null) // failure
31   *     return false;
32   * header = new SimpleNNTPHeader("foobar@foo.com", "Just testing");
33   * header.addNewsgroup("alt.test");
34   * header.addHeaderField("Organization", "Foobar, Inc.");
35   * writer.write(header.toString());
36   * writer.write("This is just a test");
37   * writer.close();
38   * if (!client.completePendingCommand()) // failure
39   *     return false;
40   * </pre>
41   *
42   * @see NNTPClient
43   */
44  
45  public class SimpleNNTPHeader {
46      private final String subject, from;
47      private final StringBuilder newsgroups;
48      private final StringBuilder headerFields;
49      private int newsgroupCount;
50  
51      /**
52       * Creates a new SimpleNNTPHeader instance initialized with the given from and subject header field values.
53       *
54       * @param from    The value of the <code>From:</code> header field. This should be the article poster's email address.
55       * @param subject The value of the <code>Subject:</code> header field. This should be the subject of the article.
56       */
57      public SimpleNNTPHeader(final String from, final String subject) {
58          this.from = from;
59          this.subject = subject;
60          this.newsgroups = new StringBuilder();
61          this.headerFields = new StringBuilder();
62          this.newsgroupCount = 0;
63      }
64  
65      /**
66       * Adds an arbitrary header field with the given value to the article header.
67       * These headers will be written after the {@code From}, Newsgroups, and Subject fields
68       * when the SimpleNNTPHeader is converted to a string. An example use would be:
69       *
70       * <pre>
71       * header.addHeaderField("Organization", "Foobar, Inc.");
72       * </pre>
73       *
74       * @param headerField The header field to add, not including the colon.
75       * @param value       The value of the added header field.
76       */
77      public void addHeaderField(final String headerField, final String value) {
78          headerFields.append(headerField);
79          headerFields.append(": ");
80          headerFields.append(value);
81          headerFields.append('\n');
82      }
83  
84      /**
85       * Adds a newsgroup to the article <code>Newsgroups:</code> field.
86       *
87       * @param newsgroup The newsgroup to add to the article's newsgroup distribution list.
88       */
89      public void addNewsgroup(final String newsgroup) {
90          if (newsgroupCount++ > 0) {
91              newsgroups.append(',');
92          }
93          newsgroups.append(newsgroup);
94      }
95  
96      /**
97       * Returns the address used in the <code> From: </code> header field.
98       *
99       * @return The from address.
100      */
101     public String getFromAddress() {
102         return from;
103     }
104 
105     /**
106      * Returns the contents of the <code> Newsgroups: </code> header field.
107      *
108      * @return The comma-separated list of newsgroups to which the article is being posted.
109      */
110     public String getNewsgroups() {
111         return newsgroups.toString();
112     }
113 
114     /**
115      * Returns the subject used in the <code> Subject: </code> header field.
116      *
117      * @return The subject.
118      */
119     public String getSubject() {
120         return subject;
121     }
122 
123     /**
124      * Converts the SimpleNNTPHeader to a properly formatted header in the form of a String, including the blank line used to separate the header from the
125      * article body.
126      *
127      * @return The article header in the form of a String.
128      */
129     @Override
130     public String toString() {
131         final StringBuilder header = new StringBuilder();
132 
133         header.append("From: ");
134         header.append(from);
135         header.append("\nNewsgroups: ");
136         header.append(newsgroups.toString());
137         header.append("\nSubject: ");
138         header.append(subject);
139         header.append('\n');
140         if (headerFields.length() > 0) {
141             header.append(headerFields.toString());
142         }
143         header.append('\n');
144 
145         return header.toString();
146     }
147 }