Adds download manager, prepares for large file downloads

Author	DaveJarvis <email>
Date	2022-12-17 17:36:42 GMT-0800
Commit	8d794de1d2a881c4622f43a5934d45bc205d582c
Parent	e767901
Delta	97 lines added, 1 line removed, 96-line increase

src/main/resources/com/keenwrite/messages.properties


		Main.status.image.request.init=Initializing HTTP request
		-Main.status.image.request.fetch=Requesting content type from ''{0}''
		+Main.status.image.request.fetch=Downloaded image ''{0}''
		Main.status.image.request.success=Determined content type ''{0}''
		Main.status.image.request.error.media=No media type for ''{0}''

src/main/java/com/keenwrite/io/downloads/events/DownloadEvent.java

		+/* Copyright 2022 White Magic Software, Ltd. -- All rights reserved. */
		+package com.keenwrite.io.downloads.events;
		+
		+import com.keenwrite.events.AppEvent;
		+
		+import java.net.URL;
		+import java.time.Instant;
		+
		+/**
		+ * The parent class to all download-related status events.
		+ */
		+public class DownloadEvent implements AppEvent {
		+
		+ private final Instant mInstant = Instant.now();
		+ private final URL mUrl;
		+
		+ /**
		+ * Constructs a new event that tracks the status of downloading a file.
		+ *
		+ * @param url The {@link URL} that has triggered a download event.
		+ */
		+ public DownloadEvent( final URL url ) {
		+ mUrl = url;
		+ }
		+
		+ /**
		+ * Returns the download link as an instance of {@link URL}.
		+ *
		+ * @return The {@link URL} being downloaded.
		+ */
		+ public URL getUrl() {
		+ return mUrl;
		+ }
		+
		+ /**
		+ * Returns the moment in time that this event was published.
		+ *
		+ * @return The published date and time.
		+ */
		+ public Instant when() {
		+ return mInstant;
		+ }
		+}

src/main/java/com/keenwrite/io/downloads/events/DownloadFailedEvent.java

		+/* Copyright 2022 White Magic Software, Ltd. -- All rights reserved. */
		+package com.keenwrite.io.downloads.events;
		+
		+import java.net.URL;
		+
		+public class DownloadFailedEvent extends DownloadEvent {
		+
		+ private final int mResponseCode;
		+
		+ /**
		+ * Constructs a new event that indicates downloading a file was not
		+ * successful.
		+ *
		+ * @param url The {@link URL} that has triggered a download event.
		+ * @param responseCode The HTTP response code associated with the failure.
		+ */
		+ public DownloadFailedEvent( final URL url, final int responseCode ) {
		+ super( url );
		+
		+ mResponseCode = responseCode;
		+ }
		+
		+ public static void fire( final URL url, final int responseCode ) {
		+ new DownloadFailedEvent( url, responseCode ).publish();
		+ }
		+
		+ /**
		+ * Returns the HTTP response code for a failed download.
		+ *
		+ * @return An HTTP response code.
		+ */
		+ public int getResponseCode() {
		+ return mResponseCode;
		+ }
		+}

src/main/java/com/keenwrite/io/downloads/events/DownloadStartedEvent.java

		+/* Copyright 2022 White Magic Software, Ltd. -- All rights reserved. */
		+package com.keenwrite.io.downloads.events;
		+
		+import java.net.URL;
		+
		+/**
		+ * Collates information about a document that has started downloading.
		+ */
		+public class DownloadStartedEvent extends DownloadEvent {
		+
		+ public DownloadStartedEvent( final URL url ) {
		+ super( url );
		+ }
		+
		+ public static void fire( final URL url ) {
		+ new DownloadStartedEvent( url ).publish();
		+ }
		+}