    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.net.nntp;
    019
    020/**
    021 * 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.
    022 * When the Java Mail API is finalized, you will be able to use it to compose fully compliant Internet text messages.
    023 * <p>
    024 * 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.
    025 * For example:
    026 * </p>
    027 *
    028 * <pre>
    029 * writer = client.postArticle();
    030 * if (writer == null) // failure
    031 *     return false;
    032 * header = new SimpleNNTPHeader("foobar@foo.com", "Just testing");
    033 * header.addNewsgroup("alt.test");
    034 * header.addHeaderField("Organization", "Foobar, Inc.");
    035 * writer.write(header.toString());
    036 * writer.write("This is just a test");
    037 * writer.close();
    038 * if (!client.completePendingCommand()) // failure
    039 *     return false;
    040 * </pre>
    041 *
    042 * @see NNTPClient
    043 */
    044
    045public class SimpleNNTPHeader {
    046    private final String subject, from;
    047    private final StringBuilder newsgroups;
    048    private final StringBuilder headerFields;
    049    private int newsgroupCount;
    050
    051    /**
    052     * Creates a new SimpleNNTPHeader instance initialized with the given from and subject header field values.
    053     *
    054     * @param from    The value of the <code>From:</code> header field. This should be the article poster's email address.
    055     * @param subject The value of the <code>Subject:</code> header field. This should be the subject of the article.
    056     */
    057    public SimpleNNTPHeader(final String from, final String subject) {
    058        this.from = from;
    059        this.subject = subject;
    060        this.newsgroups = new StringBuilder();
    061        this.headerFields = new StringBuilder();
    062        this.newsgroupCount = 0;
    063    }
    064
    065    /**
    066     * Adds an arbitrary header field with the given value to the article header.
    067     * These headers will be written after the {@code From}, Newsgroups, and Subject fields
    068     * when the SimpleNNTPHeader is converted to a string. An example use would be:
    069     *
    070     * <pre>
    071     * header.addHeaderField("Organization", "Foobar, Inc.");
    072     * </pre>
    073     *
    074     * @param headerField The header field to add, not including the colon.
    075     * @param value       The value of the added header field.
    076     */
    077    public void addHeaderField(final String headerField, final String value) {
    078        headerFields.append(headerField);
    079        headerFields.append(": ");
    080        headerFields.append(value);
    081        headerFields.append('\n');
    082    }
    083
    084    /**
    085     * Adds a newsgroup to the article <code>Newsgroups:</code> field.
    086     *
    087     * @param newsgroup The newsgroup to add to the article's newsgroup distribution list.
    088     */
    089    public void addNewsgroup(final String newsgroup) {
    090        if (newsgroupCount++ > 0) {
    091            newsgroups.append(',');
    092        }
    093        newsgroups.append(newsgroup);
    094    }
    095
    096    /**
    097     * Returns the address used in the <code> From: </code> header field.
    098     *
    099     * @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}