--- a/src/java.base/share/classes/java/net/URL.java	Thu May 02 14:21:06 2019 -0700
+++ b/src/java.base/share/classes/java/net/URL.java	Thu May 02 22:52:51 2019 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1995, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1403,8 +1403,9 @@
 
         URLStreamHandlerFactory fac;
         boolean checkedWithFactory = false;
+        boolean overrideableProtocol = isOverrideable(protocol);
 
-        if (isOverrideable(protocol) && jdk.internal.misc.VM.isBooted()) {
+        if (overrideableProtocol && jdk.internal.misc.VM.isBooted()) {
             // Use the factory (if any). Volatile read makes
             // URLStreamHandlerFactory appear fully initialized to current thread.
             fac = factory;
@@ -1440,7 +1441,8 @@
 
             // Check with factory if another thread set a
             // factory since our last check
-            if (!checkedWithFactory && (fac = factory) != null) {
+            if (overrideableProtocol && !checkedWithFactory &&
+                (fac = factory) != null) {
                 handler2 = fac.createURLStreamHandler(protocol);
             }
 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/jdk/java/net/URL/NonOverridableHandlerFactory.java	Thu May 02 22:52:51 2019 +0100
@@ -0,0 +1,64 @@
+/*
+ * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code 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
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8217364
+ * @summary Custom URLStreamHandler for jrt or file protocol can override default handler
+ * @modules java.base/java.net:open
+ * @run main/othervm NonOverridableHandlerFactory
+ */
+
+import java.io.*;
+import java.net.*;
+
+public class NonOverridableHandlerFactory implements URLStreamHandlerFactory {
+    @Override
+    public URLStreamHandler createURLStreamHandler(String protocol) {
+        return new NonOverridableHandler();
+    }
+
+    private static class NonOverridableHandler extends URLStreamHandler {
+        @Override
+        protected URLConnection openConnection(URL u) throws IOException {
+            throw new RuntimeException("CustomURLStreamHandler used for " + u);
+        }
+    }
+
+    public static void main(String[] args) {
+        URL.setURLStreamHandlerFactory(new NonOverridableHandlerFactory());
+        for (String protocol : new String[] {"file", "jrt"}) {
+            String urlString = protocol + ":///test/somefile";
+            try {
+                new URL(urlString).openConnection();
+            } catch(RuntimeException r) {
+                throw r;
+            } catch(Throwable t) {
+                // possible jrt initialization issue on exploded binary image etc.
+                System.out.println("encountered: " + t +
+                    "(testing: " + urlString + ")");
+            }
+            System.out.println("Default URLStreamHandler used for " + urlString);
+        }
+    }
+}