Fixed - `factory already defined` error during Redisson initialization. #734

redisson/src/main/java/org/redisson/misc/URLBuilder.java

@@ -16,6 +16,7 @@
 package org.redisson.misc;
 
 import java.io.IOException;
+import java.lang.reflect.Field;
 import java.net.InetSocketAddress;
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -41,31 +42,46 @@ public class URLBuilder {
             return;
         }
         init = true;
-        URL.setURLStreamHandlerFactory(new URLStreamHandlerFactory() {
-            @Override
-            public URLStreamHandler createURLStreamHandler(String protocol) {
-                if ("redis".equals(protocol)) {
-                    return new URLStreamHandler() {
-                        @Override
-                        protected URLConnection openConnection(URL u) throws IOException {
-                            throw new UnsupportedOperationException();
+        
+        try {
+            Field field = URL.class.getDeclaredField("factory");
+            field.setAccessible(true);
+            final URLStreamHandlerFactory currentFactory = (URLStreamHandlerFactory) field.get(null);
+            if (currentFactory != null) {
+                field.set(null, null);
+            }
+            
+            URL.setURLStreamHandlerFactory(new URLStreamHandlerFactory() {
+                @Override
+                public URLStreamHandler createURLStreamHandler(String protocol) {
+                    if ("redis".equals(protocol)) {
+                        return new URLStreamHandler() {
+                            @Override
+                            protected URLConnection openConnection(URL u) throws IOException {
+                                throw new UnsupportedOperationException();
+                            };
+                            
+                            @Override
+                            protected boolean equals(URL u1, URL u2) {
+                                return u1.toString().equals(u2.toString());
+                            }
+                            
+                            @Override
+                            protected int hashCode(URL u) {
+                                return u.toString().hashCode();
+                            }
                         };
-                        
-                        @Override
-                        protected boolean equals(URL u1, URL u2) {
-                            return u1.toString().equals(u2.toString());
-                        }
-                        
-                        @Override
-                        protected int hashCode(URL u) {
-                            return u.toString().hashCode();
-                        }
-                        
-                    };
+                    }
+                    
+                    if (currentFactory != null) {
+                        return currentFactory.createURLStreamHandler(protocol);
+                    }
+                    return null;
                 }
-                return null;
-            }
-        });
+            });
+        } catch (Exception e) {
+            throw new IllegalStateException(e);
+        }
     }
 
     public static InetSocketAddress toAddress(String url) {