#// Usage: jjs -scripting gutenberg.js+
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+
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/*+
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 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.+
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 *+
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 * Redistribution and use in source and binary forms, with or without+
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 * modification, are permitted provided that the following conditions+
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 * are met:+
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 *+
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 *   - Redistributions of source code must retain the above copyright+
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 *     notice, this list of conditions and the following disclaimer.+
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 *+
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 *   - Redistributions in binary form must reproduce the above copyright+
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 *     notice, this list of conditions and the following disclaimer in the+
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 *     documentation and/or other materials provided with the distribution.+
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 *+
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 *   - Neither the name of Oracle nor the names of its+
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 *     contributors may be used to endorse or promote products derived+
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 *     from this software without specific prior written permission.+
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 *+
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS+
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 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,+
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 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR+
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 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR+
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 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,+
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 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,+
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 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR+
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 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF+
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 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING+
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 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS+
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.+
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 */+
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+
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// Simple example that demonstrates reading XML Rss feed+
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// to generate a HTML file from script and show it by browser+
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+
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// Java classes used+
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var Characters = Java.type("javax.xml.stream.events.Characters");+
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var Factory = Java.type("javax.xml.stream.XMLInputFactory");+
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var File = Java.type("java.io.File");+
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var FileWriter = Java.type("java.io.FileWriter");+
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var PrintWriter = Java.type("java.io.PrintWriter");+
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var URL = Java.type("java.net.URL");+
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+
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// read Rss feed from a URL. Returns an array+
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// of objects having only title and link properties+
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function readRssFeed(url) {+
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    var fac = Factory.newInstance();+
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    var reader = fac.createXMLEventReader(url.openStream());+
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+
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    // get text content from next event+
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    function getChars() {+
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        var result = "";+
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        var e = reader.nextEvent();+
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        if (e instanceof Characters) {+
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            result = e.getData();+
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        }+
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        return result;+
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    }+
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+
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    var items = [];+
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    var title, link;+
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    var inItem = false;+
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    while (reader.hasNext()) {+
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        var evt = reader.nextEvent();+
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        if (evt.isStartElement()) {+
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            var local = evt.name.localPart;+
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            if (local == "item") {+
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               // capture title, description now+
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               inItem = true;+
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            }+
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+
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            if (inItem) {+
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                switch (local) {+
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                    case 'title':+
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                        title = getChars();+
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                        break;+
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                    case 'link':+
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                        link = getChars();+
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                        break;+
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                }+
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            }+
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        } else if (evt.isEndElement()) {+
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            var local = evt.name.localPart;+
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            if (local == "item") {+
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                // one item done, save it in result array+
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                items.push({ title: title, link: link });+
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                inItem = false;+
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            }+
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        }+
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    }+
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+
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    return items;+
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}+
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+
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// generate simple HTML for an RSS feed+
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function getBooksHtml() {+
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    var url = new URL("http://www.gutenberg.org/cache/epub/feeds/today.rss");+
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    var items = readRssFeed(url);+
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+
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    var str = "<ul>";+
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+
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    // Nashorn's string interpolation and heredoc+
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    // support is very handy in generating text content+
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    // that is filled with elements from runtime objects.+
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    // We insert title and link in <li> elements here.+
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    for each (i in items) {+
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        str += <<EOF+
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<li>+
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    <a href="${i.link}">${i.title}</a>+
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</li>+
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EOF+
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    }+
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    str += "</ul>";+
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    return str;+
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}+
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+
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// write the string to the given file+
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function writeTo(file, str) {+
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    var w = new PrintWriter(new FileWriter(file));+
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    try {+
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        w.print(str);+
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    } finally {+
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        w.close();+
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    }+
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}+
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+
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// generate books HTML+
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var str = getBooksHtml();+
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+
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// write to file. __DIR__ is directory where+
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// this script is stored.+
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var file = new File(__DIR__ + "books.html");+
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writeTo(file, str);+
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+
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// show it by desktop browser+
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try {+
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    var Desktop = Java.type("java.awt.Desktop");+
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    Desktop.desktop.browse(file.toURI());+
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} catch (e) {+
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    print(e);+
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}+
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