8009645: ClassFileTransformer hooks in ClassLoader no longer required

Reviewed-by: mchung, iris

src/share/classes/java/lang/ClassLoader.java

@@ -51,7 +51,6 @@ import java.util.Vector;
 import java.util.Hashtable;
 import java.util.WeakHashMap;
 import java.util.concurrent.ConcurrentHashMap;
-import sun.misc.ClassFileTransformer;
 import sun.misc.CompoundEnumeration;
 import sun.misc.Resource;
 import sun.misc.URLClassPath;
@@ -669,41 +668,6 @@ public abstract class ClassLoader {
         return source;
     }
 
-    private Class<?> defineTransformedClass(String name, byte[] b, int off, int len,
-                                            ProtectionDomain pd,
-                                            ClassFormatError cfe, String source)
-      throws ClassFormatError
-    {
-        // Class format error - try to transform the bytecode and
-        // define the class again
-        //
-        ClassFileTransformer[] transformers =
-            ClassFileTransformer.getTransformers();
-        Class<?> c = null;
-
-        if (transformers != null) {
-            for (ClassFileTransformer transformer : transformers) {
-                try {
-                    // Transform byte code using transformer
-                    byte[] tb = transformer.transform(b, off, len);
-                    c = defineClass1(name, tb, 0, tb.length,
-                                     pd, source);
-                    break;
-                } catch (ClassFormatError cfe2)     {
-                    // If ClassFormatError occurs, try next transformer
-                }
-            }
-        }
-
-        // Rethrow original ClassFormatError if unable to transform
-        // bytecode to well-formed
-        //
-        if (c == null)
-            throw cfe;
-
-        return c;
-    }
-
     private void postDefineClass(Class<?> c, ProtectionDomain pd)
     {
         if (pd.getCodeSource() != null) {
@@ -783,17 +747,8 @@ public abstract class ClassLoader {
         throws ClassFormatError
     {
         protectionDomain = preDefineClass(name, protectionDomain);
-
-        Class<?> c = null;
         String source = defineClassSourceLocation(protectionDomain);
-
-        try {
-            c = defineClass1(name, b, off, len, protectionDomain, source);
-        } catch (ClassFormatError cfe) {
-            c = defineTransformedClass(name, b, off, len, protectionDomain, cfe,
-                                       source);
-        }
-
+        Class<?> c = defineClass1(name, b, off, len, protectionDomain, source);
         postDefineClass(c, protectionDomain);
         return c;
     }
@@ -881,20 +836,8 @@ public abstract class ClassLoader {
         }
 
         protectionDomain = preDefineClass(name, protectionDomain);
-
-        Class<?> c = null;
         String source = defineClassSourceLocation(protectionDomain);
-
-        try {
-            c = defineClass2(name, b, b.position(), len, protectionDomain,
-                             source);
-        } catch (ClassFormatError cfe) {
-            byte[] tb = new byte[len];
-            b.get(tb);  // get bytes out of byte buffer.
-            c = defineTransformedClass(name, tb, 0, len, protectionDomain, cfe,
-                                       source);
-        }
-
+        Class<?> c = defineClass2(name, b, b.position(), len, protectionDomain, source);
         postDefineClass(c, protectionDomain);
         return c;
     }

src/share/classes/sun/misc/ClassFileTransformer.java

@@ -25,43 +25,31 @@
 package sun.misc;
 
 import java.util.ArrayList;
+import java.util.List;
 
 /**
- * This is an abstract base class which is called by java.lang.ClassLoader
- * when ClassFormatError is thrown inside defineClass().
- *
- * The purpose of this class is to allow applications (e.g. Java Plug-in)
- * to have a chance to transform the byte code from one form to another
- * if necessary.
- *
- * One application of this class is used by Java Plug-in to transform
- * malformed JDK 1.1 class file into a well-formed Java 2 class file
- * on-the-fly, so JDK 1.1 applets with malformed class file in the
- * Internet may run in Java 2 after transformation.
+ * This is an abstract base class originally intended to be called by
+ * {@code java.lang.ClassLoader} when {@code ClassFormatError} is
+ * thrown inside {@code defineClass()}. It is no longer hooked into
+ * {@code ClassLoader} and will be removed in a future release.
  *
  * @author      Stanley Man-Kit Ho
  */
 
-public abstract class ClassFileTransformer
-{
-    // Singleton of ClassFileTransformer
-    //
-    private static ArrayList<ClassFileTransformer> transformerList
+@Deprecated
+public abstract class ClassFileTransformer {
+
+    private static final List<ClassFileTransformer> transformers
         = new ArrayList<ClassFileTransformer>();
-    private static ClassFileTransformer[] transformers
-        = new ClassFileTransformer[0];
 
     /**
      * Add the class file transformer object.
      *
      * @param t Class file transformer instance
      */
-    public static void add(ClassFileTransformer t)
-    {
-        synchronized(transformerList)
-        {
-            transformerList.add(t);
-            transformers = transformerList.toArray(new ClassFileTransformer[0]);
+    public static void add(ClassFileTransformer t) {
+        synchronized (transformers) {
+            transformers.add(t);
         }
     }
 
@@ -70,13 +58,11 @@ public abstract class ClassFileTransformer
      *
      * @return ClassFileTransformer object array
      */
-    public static ClassFileTransformer[] getTransformers()
-    {
-        // transformers is not intended to be changed frequently,
-        // so it is okay to not put synchronized block here
-        // to speed up performance.
-        //
-        return transformers;
+    public static ClassFileTransformer[] getTransformers() {
+        synchronized (transformers) {
+            ClassFileTransformer[] result = new ClassFileTransformer[transformers.size()];
+            return transformers.toArray(result);
+        }
     }
 
 
@@ -89,5 +75,5 @@ public abstract class ClassFileTransformer
      * @return Transformed byte array
      */
     public abstract byte[] transform(byte[] b, int off, int len)
-                           throws ClassFormatError;
+        throws ClassFormatError;
 }