    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 *      https://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;
    047    private final String from;
    048    private final StringBuilder newsgroups;
    049    private final StringBuilder headerFields;
    050    private int newsgroupCount;
    051
    052    /**
    053     * Creates a new SimpleNNTPHeader instance initialized with the given from and subject header field values.
    054     *
    055     * @param from    The value of the {@code From:} header field. This should be the article poster's email address.
    056     * @param subject The value of the {@code Subject:} header field. This should be the subject of the article.
    057     */
    058    public SimpleNNTPHeader(final String from, final String subject) {
    059        this.from = from;
    060        this.subject = subject;
    061        this.newsgroups = new StringBuilder();
    062        this.headerFields = new StringBuilder();
    063        this.newsgroupCount = 0;
    064    }
    065
    066    /**
    067     * Adds an arbitrary header field with the given value to the article header.
    068     * These headers will be written after the {@code From}, Newsgroups, and Subject fields
    069     * when the SimpleNNTPHeader is converted to a string. An example use would be:
    070     *
    071     * <pre>
    072     * header.addHeaderField("Organization", "Foobar, Inc.");
    073     * </pre>
    074     *
    075     * @param headerField The header field to add, not including the colon.
    076     * @param value       The value of the added header field.
    077     */
    078    public void addHeaderField(final String headerField, final String value) {
    079        headerFields.append(headerField);
    080        headerFields.append(": ");
    081        headerFields.append(value);
    082        headerFields.append('\n');
    083    }
    084
    085    /**
    086     * Adds a newsgroup to the article {@code Newsgroups:} field.
    087     *
    088     * @param newsgroup The newsgroup to add to the article's newsgroup distribution list.
    089     */
    090    public void addNewsgroup(final String newsgroup) {
    091        if (newsgroupCount++ > 0) {
    092            newsgroups.append(',');
    093        }
    094        newsgroups.append(newsgroup);
    095    }
    096
    097    /**
    098     * Gets the address used in the {@code From:} header field.
    099     *
    100     * @return The from address.
    101     */
    102    public String getFromAddress() {
    103        return from;
    104    }
    105
    106    /**
    107     * Gets the contents of the {@code Newsgroups:} header field.
    108     *
    109     * @return The comma-separated list of newsgroups to which the article is being posted.
    110     */
    111    public String getNewsgroups() {
    112        return newsgroups.toString();
    113    }
    114
    115    /**
    116     * Gets the subject used in the {@code Subject:} header field.
    117     *
    118     * @return The subject.
    119     */
    120    public String getSubject() {
    121        return subject;
    122    }
    123
    124    /**
    125     * 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
    126     * article body.
    127     *
    128     * @return The article header in the form of a String.
    129     */
    130    @Override
    131    public String toString() {
    132        final StringBuilder header = new StringBuilder();
    133
    134        header.append("From: ");
    135        header.append(from);
    136        header.append("\nNewsgroups: ");
    137        header.append(newsgroups.toString());
    138        header.append("\nSubject: ");
    139        header.append(subject);
    140        header.append('\n');
    141        if (headerFields.length() > 0) {
    142            header.append(headerFields.toString());
    143        }
    144        header.append('\n');
    145
    146        return header.toString();
    147    }
    148}