generate podcast feed based on contents of directory

PodCastFeedGenerator.java

package com.company;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.util.List;
import java.util.Date;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Locale;


public class PodCastFeedGenerator {

    private String sourceFileDirectory;
    private String destinationXmlFeed;
    private String websiteUrlBase;

    public static void main(String[] args) throws Exception {
        checkArgs(args);
        String sourceFiles = args[0];
        String destinationXmlFeed = args[1];
        String websiteUrlBase = args[2];
        PodCastFeedGenerator feedGenerator = new PodCastFeedGenerator(sourceFiles, destinationXmlFeed, websiteUrlBase);
        feedGenerator.generateFeed();
    }

    public static void checkArgs(String[] args) {
        if (args.length < 3) {
            System.out.println("Please provide args: sourceFiles destinationXml websiteUrlBase");
            System.exit(1);
        }

    }

    public PodCastFeedGenerator(String sourceFileDirectory, String destinationXmlFeed, String websiteUrlBase) {
        this.sourceFileDirectory = sourceFileDirectory;
        this.destinationXmlFeed = destinationXmlFeed;
        this.websiteUrlBase = websiteUrlBase;
    }

    public void generateFeed() throws Exception {
        List<File> sourceFiles = listAllFilesInDirectoryWithExtension(sourceFileDirectory, "m4a");
        String xmlFeed = generateRssFeedXmlHeader() + generateRssFeedXmlBody(sourceFiles) + generateRssFeedXmlFooter();
        writeXmlFeedToFile(xmlFeed, destinationXmlFeed);
    }

    private void writeXmlFeedToFile(String xmlFeed, String destinationXmlFeed) throws IOException {
        FileWriter fileWriter = new FileWriter(destinationXmlFeed);
        fileWriter.write(xmlFeed);
        fileWriter.close();
    }

    //takes a directory as a string and returns a list of all files in that directory
    //that match the file extension (eg. "mp3")
    private List<File> listAllFilesInDirectoryWithExtension(String sourceFileDirectory, String extension) {
        File directory = new File(sourceFileDirectory);
        File[] files = directory.listFiles();
        List<File> matchingFiles = new java.util.ArrayList<File>();
        for (File file : files) {
            if (file.getName().endsWith(extension)) {
                matchingFiles.add(file);
            }
        }
        return matchingFiles;
    }

    private String generateRssFeedXmlHeader() {
        DateFormat df = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z", Locale.US);
        String formattedDate = df.format(new Date());
    
        String rssFeedXml = "<?xml version='1.0' encoding='UTF-8'?>\n" +
                "<rss xmlns:atom=\"http://www.w3.org/2005/Atom\" xmlns:content=\"http://purl.org/rss/1.0/modules/content/\" xmlns:itunes=\"http://www.itunes.com/dtds/podcast-1.0.dtd\" xmlns:dc=\"http://purl.org/dc/elements/1.1/\" version=\"2.0\">\n" +
                "    <channel>\n" +
                "        <title>Gorbanvs Great Podcast Name</title>\n" +
                "        <link>" + this.websiteUrlBase + "</link>\n" +
                "        <description>PodCast Description</description>\n" +
                "        <lastBuildDate>" + formattedDate + "</lastBuildDate>\n" ;
                return  rssFeedXml;

    }

    private String generateRssFeedXmlBody(List<File> sourceFiles) throws Exception {
        String rssFeedXml = "";
        String link = "";
        long fileLength = 0;
        DateFormat df = new SimpleDateFormat("EEE, d MMM yyyy HH:mm:ss Z", Locale.US);
        String formattedDate = "";

        for (File file : sourceFiles) {
            link = java.net.URLEncoder.encode(file.getName(), "UTF-8").replace("+", "%20");
            fileLength = file.length();

            //get modified date of file
            long lastModified = file.lastModified();
    
            //convert long to date
            java.util.Date date = new java.util.Date(lastModified);

            formattedDate = df.format(date);
    
            rssFeedXml += "        <item>\n" +
                    "            <title><![CDATA[" + file.getName() + "]]></title>\n" +
                    "            <pubDate>" + formattedDate + "</pubDate>\n" +
                    "            <guid isPermaLink=\"false\"><![CDATA[" + file.getName() + "]]></guid>\n" +
                    "            <link>" + this.websiteUrlBase + "/" + link + "</link>\n" +
                    "            <description><![CDATA[" + file.getName() + "]]></description>\n" +
                    "            <enclosure url=\"" + this.websiteUrlBase + "/" + link + "\" length=\"" + String.valueOf(fileLength) + "\" type=\"audio/mpeg\" />\n" +
                    "        </item>\n";

        }
        return rssFeedXml;
    }

    private String generateRssFeedXmlFooter() {
        String rssFeedXml = "    </channel>\n" +
                "</rss>\n";
        return rssFeedXml;
    }

}