Only use DatatypeConverter as a fallback

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

libraries/launcher/CMakeLists.txt

@@ -19,6 +19,8 @@ set(SRC
     org/prismlauncher/fix/Fixes.java
     org/prismlauncher/fix/skins/SkinFix.java
     org/prismlauncher/fix/skins/Handler.java
+    org/prismlauncher/utils/Base64.java
+    org/prismlauncher/utils/JsonParser.java
     org/prismlauncher/utils/Parameters.java
     org/prismlauncher/utils/ReflectionUtils.java
     org/prismlauncher/utils/UrlUtils.java

libraries/launcher/org/prismlauncher/fix/skins/Handler.java

@@ -43,8 +43,7 @@ import java.net.URLConnection;
 import java.net.URLStreamHandler;
 import java.util.Map;
 
-import javax.xml.bind.DatatypeConverter;
-
+import org.prismlauncher.utils.Base64;
 import org.prismlauncher.utils.JsonParser;
 import org.prismlauncher.utils.UrlUtils;
 
@@ -115,7 +114,7 @@ final class Handler extends URLStreamHandler {
                 for (Map<String, Object> property : (Iterable<Map<String, Object>>) profile.get("properties")) {
                     if (property.get("name").equals("textures")) {
                         Map<String, Object> result = (Map<String, Object>) JsonParser
-                                .parse(new String(DatatypeConverter.parseBase64Binary((String) property.get("value"))));
+                                .parse(new String(Base64.decode((String) property.get("value"))));
                         result = (Map<String, Object>) result.get("textures");
                         return result;
                     }

libraries/launcher/org/prismlauncher/fix/skins/SkinFix.java

@@ -59,27 +59,10 @@ public final class SkinFix implements Fix, URLStreamHandlerFactory {
 
     @Override
     public boolean isApplicable(Parameters params) {
-        if (!isSupported()) {
-            Log.warning("Using Java 8 will probably fix this");
-            Log.warning("Alternatively, turning off legacy skin fix in Settings > Miscellaneous will silence the warnings");
-            return false;
-        }
-
-        return true;
-    }
-
-    private boolean isSupported() {
-        // check for DatatypeConverter first
-        // most users will just be annoyed by the big stacktrace
-        try {
-            Class.forName("javax.xml.bind.DatatypeConverter");
-        } catch (ClassNotFoundException e) {
-            Log.warning("Cannot find DatatypeConverter - required for skin fix");
-            return false;
-        }
-
         if (!UrlUtils.isSupported()) {
             Log.warning("Cannot access the necessary Java internals for skin fix");
+            Log.warning("Using an older Java version will probably fix this");
+            Log.warning("Alternatively, turning off legacy skin fix in Settings > Miscellaneous will silence the warnings");
             return false;
         }
 

libraries/launcher/org/prismlauncher/utils/Base64.java

@@ -0,0 +1,59 @@
+// SPDX-License-Identifier: GPL-3.0-only
+/*
+ *  Prism Launcher - Minecraft Launcher
+ *  Copyright (C) 2022 TheKodeToad <TheKodeToad@proton.me>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, version 3.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  Linking this library statically or dynamically with other modules is
+ *  making a combined work based on this library. Thus, the terms and
+ *  conditions of the GNU General Public License cover the whole
+ *  combination.
+ *
+ *  As a special exception, the copyright holders of this library give
+ *  you permission to link this library with independent modules to
+ *  produce an executable, regardless of the license terms of these
+ *  independent modules, and to copy and distribute the resulting
+ *  executable under terms of your choice, provided that you also meet,
+ *  for each linked independent module, the terms and conditions of the
+ *  license of that module. An independent module is a module which is
+ *  not derived from or based on this library. If you modify this
+ *  library, you may extend this exception to your version of the
+ *  library, but you are not obliged to do so. If you do not wish to do
+ *  so, delete this exception statement from your version.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.prismlauncher.utils;
+
+import java.nio.charset.StandardCharsets;
+
+import javax.xml.bind.DatatypeConverter;
+
+public final class Base64 {
+
+    private static boolean legacy;
+
+    public static byte[] decode(String input) {
+        if (!legacy) {
+            try {
+                return java.util.Base64.getDecoder().decode(input.getBytes(StandardCharsets.UTF_8));
+            } catch (NoClassDefFoundError e) {
+                legacy = true;
+            }
+        }
+
+        // support for Java versions < 8
+        return DatatypeConverter.parseBase64Binary(input);
+    }
+
+}

libraries/launcher/org/prismlauncher/utils/JsonParser.java

@@ -420,7 +420,7 @@ public final class JsonParser {
         return character() == 'n' && read() == 'u' && read() == 'l' && read() == 'l';
     }
 
-    public class JsonParseException extends IOException {
+    public static class JsonParseException extends IOException {
 
         private static final long serialVersionUID = 1L;
 

libraries/launcher/org/prismlauncher/utils/UrlUtils.java

@@ -50,7 +50,7 @@ import org.prismlauncher.utils.logging.Log;
  * A utility class for URLs which uses reflection to access hidden methods.
  * Unfortunately not supported on newer Java versions.
  */
-public class UrlUtils {
+public final class UrlUtils {
 
     private static URLStreamHandler http;
     private static MethodHandle openConnection;