I think this should be working now!

forge-gui/src/main/java/forge/download/AutoUpdater.java

@@ -13,19 +13,24 @@ import javax.swing.*;
 import java.awt.*;
 import java.io.IOException;
 import java.io.InputStream;
-import java.lang.reflect.InvocationTargetException;
 import java.net.*;
 import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 
 public class AutoUpdater {
+    private final String SNAPSHOT_VERSION_INDEX = "https://snapshots.cardforge.org/";
     private final String SNAPSHOT_VERSION_URL = "https://snapshots.cardforge.org/version.txt";
     private final String SNAPSHOT_PACKAGE = "https://snapshots.cardforge.org/latest/";
     private final String RELEASE_VERSION_URL = "https://releases.cardforge.org/forge/forge-gui-desktop/version.txt";
     private final String RELEASE_PACKAGE = "https://releases.cardforge.org/latest/";
+    private final String RELEASE_MAVEN_METADATA = "https://releases.cardforge.org/forge/forge-gui-desktop/maven-metadata.xml";
+    private static final boolean VERSION_FROM_METADATA = true;
 
     public static String[] updateChannels = new String[]{ "None", "Snapshot", "Release"};
 
     private boolean isLoading;
+    private String updateChannel;
     private String version;
     private String buildVersion;
     private String versionUrlString;
@@ -35,6 +40,8 @@ public class AutoUpdater {
     public AutoUpdater(boolean loading) {
         // What do I need? Preferences? Splashscreen? UI? Skins?
         isLoading = loading;
+        final ForgePreferences.FPref updatePreference = ForgePreferences.FPref.AUTO_UPDATE;
+        updateChannel = "release"; //this.prefs.getPref(updatePreference);
     }
 
     public boolean attemptToUpdate() {
@@ -55,10 +62,6 @@ public class AutoUpdater {
     }
 
     private boolean verifyUpdateable() {
-        // Check the preferences
-        final ForgePreferences.FPref updatePreference = ForgePreferences.FPref.AUTO_UPDATE;
-        final String updateChannel =  "release"; //this.prefs.getPref(updatePreference);
-
         if (isLoading) {
             // TODO This doesn't work yet, because FSkin isn't loaded at the time.
             return false;
@@ -95,14 +98,17 @@ public class AutoUpdater {
 
     private boolean compareBuildWithLatestChannelVersion() {
         try {
-            URL versionUrl = new URL(versionUrlString);
+            retrieveVersion();
-            version = FileUtil.readFileToString(versionUrl);
 
             buildVersion = BuildInfo.getVersionString();
 
-            // Return false if buildVersion == GIT
+            if (buildVersion.contains("SNAPSHOT") && !updateChannel.equals("snapshot")) {
+                System.out.println("Snapshot build versions must use snapshot update channel to work");
+                return false;
+            }
+
             if (buildVersion.equalsIgnoreCase("GIT") || StringUtils.isEmpty(version) ) {
-                // return false;
+                return false;
             }
 
             if (buildVersion.equals(version)) {
@@ -116,6 +122,42 @@ public class AutoUpdater {
         return true;
     }
 
+    private void retrieveVersion() throws MalformedURLException {
+        if (VERSION_FROM_METADATA) {
+            if (!updateChannel.equals("release")) {
+                extractVersionFromMavenRelease();
+            } else {
+                extractVersionFromSnapshotIndex();
+            }
+        } else {
+            URL versionUrl = new URL(versionUrlString);
+            version = FileUtil.readFileToString(versionUrl);
+        }
+    }
+
+    private void extractVersionFromSnapshotIndex() throws MalformedURLException {
+        URL metadataUrl = new URL(SNAPSHOT_VERSION_INDEX);
+        String index = FileUtil.readFileToString(metadataUrl);
+
+        System.out.println(index);
+        Pattern p = Pattern.compile(">forge-(.*SNAPSHOT)");
+        Matcher m = p.matcher(index);
+        while(m.find()){
+            version = m.group(1);
+        }
+    }
+
+    private void extractVersionFromMavenRelease() throws MalformedURLException {
+        URL metadataUrl = new URL(RELEASE_MAVEN_METADATA);
+        String xml = FileUtil.readFileToString(metadataUrl);
+
+        Pattern p = Pattern.compile("<release>(.*)</release>");
+        Matcher m = p.matcher(xml);
+        while(m.find()){
+            version = m.group(1);
+        }
+    }
+
     private boolean downloadUpdate() throws URISyntaxException, IOException {
         // We need to preload enough of a Skins to show a dialog and a button if we're in loading
         // splashScreen.prepareForDialogs();
@@ -126,7 +168,7 @@ public class AutoUpdater {
         }
 
         String message = "A new version of Forge is available (" + version + ").\n" +
-                "You are currently on an older version (" + buildVersion + ").\n\n" +
+                "You are currently on version (" + buildVersion + ").\n\n" +
                 "Would you like to update to the new version now?";
 
         final List<String> options = ImmutableList.of("Update Now", "Update Later");