extracting class resolving role to separate interface

src/main/java/org/jboss/netty/handler/codec/serialization/CachingClassResolver.java

@@ -0,0 +1,31 @@
+package org.jboss.netty.handler.codec.serialization;
+
+import java.util.Map;
+
+class CachingClassResolver implements ClassResolver {
+
+    private final Map<String, Class<?>> classCache;
+    private final ClassResolver delegate;
+
+    CachingClassResolver(ClassResolver delegate, Map<String, Class<?>> classCache) {
+        this.delegate = delegate;
+        this.classCache = classCache;
+    }
+
+    @Override
+    public Class<?> resolve(String className) throws ClassNotFoundException {
+        // Query the cache first.
+        Class<?> clazz;
+        clazz = classCache.get(className);
+        if (clazz != null) {
+            return clazz;
+        }
+
+        // And then try to load.
+        clazz = delegate.resolve(className);
+
+        classCache.put(className, clazz);
+        return clazz;
+    }
+
+}

src/main/java/org/jboss/netty/handler/codec/serialization/ClassResolver.java

@@ -0,0 +1,7 @@
+package org.jboss.netty.handler.codec.serialization;
+
+interface ClassResolver {
+
+    Class<?> resolve(String className) throws ClassNotFoundException;
+
+}

src/main/java/org/jboss/netty/handler/codec/serialization/ClassResolvers.java

@@ -0,0 +1,24 @@
+package org.jboss.netty.handler.codec.serialization;
+
+import java.util.HashMap;
+
+public class ClassResolvers {
+    
+    public static ClassResolver cachingResolver(ClassLoader classLoader) {
+        if (classLoader == null) {
+            classLoader = defaultClassLoader();
+        }
+
+        return new CachingClassResolver(new ClassloaderClassResolver(classLoader), new HashMap<String, Class<?>>());
+    }
+    
+    static ClassLoader defaultClassLoader() {
+        final ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
+        if (contextClassLoader != null) {
+            return contextClassLoader;
+        }
+
+        return CompactObjectInputStream.class.getClassLoader();
+    }
+
+}

src/main/java/org/jboss/netty/handler/codec/serialization/ClassloaderClassResolver.java

@@ -0,0 +1,16 @@
+package org.jboss.netty.handler.codec.serialization;
+
+class ClassloaderClassResolver implements ClassResolver {
+
+    private final ClassLoader classLoader;
+
+    ClassloaderClassResolver(ClassLoader classLoader) {
+        this.classLoader = classLoader;
+    }
+
+    @Override
+    public Class<?> resolve(String className) throws ClassNotFoundException {
+        return classLoader.loadClass(className);
+    }
+
+}

src/main/java/org/jboss/netty/handler/codec/serialization/CompactObjectInputStream.java

@@ -21,8 +21,6 @@ import java.io.InputStream;
 import java.io.ObjectInputStream;
 import java.io.ObjectStreamClass;
 import java.io.StreamCorruptedException;
-import java.util.HashMap;
-import java.util.Map;
 
 /**
  * @author <a href="http://www.jboss.org/netty/">The Netty Project</a>
@@ -33,20 +31,11 @@ import java.util.Map;
  */
 class CompactObjectInputStream extends ObjectInputStream {
     
-    private final Map<String, Class<?>> classCache = new HashMap<String, Class<?>>();
-    private final ClassLoader classLoader;
+    private final ClassResolver classResolver;
 
-    CompactObjectInputStream(InputStream in) throws IOException {
-        this(in, null);
-    }
-
-    CompactObjectInputStream(InputStream in, ClassLoader classLoader) throws IOException {
+    CompactObjectInputStream(InputStream in, ClassResolver classResolver) throws IOException {
         super(in);
-        if (classLoader == null) {
-            this.classLoader = defaultClassLoader();
-        } else {
-            this.classLoader = classLoader;
-        }
+        this.classResolver = classResolver;
     }
 
     @Override
@@ -70,7 +59,7 @@ class CompactObjectInputStream extends ObjectInputStream {
             return super.readClassDescriptor();
         case CompactObjectOutputStream.TYPE_THIN_DESCRIPTOR:
             String className = readUTF();
-            Class<?> clazz = loadClass(className);
+            Class<?> clazz = classResolver.resolve(className);
             return ObjectStreamClass.lookupAny(clazz);
         default:
             throw new StreamCorruptedException(
@@ -82,7 +71,7 @@ class CompactObjectInputStream extends ObjectInputStream {
     protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
         Class<?> clazz;
         try {
-            clazz = loadClass(desc.getName());
+            clazz = classResolver.resolve(desc.getName());
         } catch (ClassNotFoundException ex) {
             clazz = super.resolveClass(desc);
         }
@@ -90,28 +79,4 @@ class CompactObjectInputStream extends ObjectInputStream {
         return clazz;
     }
 
-    protected Class<?> loadClass(String className) throws ClassNotFoundException {
-        // Query the cache first.
-        Class<?> clazz;
-        clazz = classCache.get(className);
-        if (clazz != null) {
-            return clazz;
-        }
-
-        // And then try to load.
-        clazz = classLoader.loadClass(className);
-
-        classCache.put(className, clazz);
-        return clazz;
-    }
-
-    private static ClassLoader defaultClassLoader() {
-        final ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
-        if (contextClassLoader != null) {
-            return contextClassLoader;
-        }
-
-        return CompactObjectInputStream.class.getClassLoader();
-    }
-
 }

src/main/java/org/jboss/netty/handler/codec/serialization/ObjectDecoder.java

@@ -43,7 +43,7 @@ import org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder;
  */
 public class ObjectDecoder extends LengthFieldBasedFrameDecoder {
 
-    private final ClassLoader classLoader;
+    private final ClassResolver classResolver;
 
     /**
      * Creates a new decoder whose maximum object size is {@code 1048576}
@@ -64,7 +64,7 @@ public class ObjectDecoder extends LengthFieldBasedFrameDecoder {
      *                       will be raised.
      */
     public ObjectDecoder(int maxObjectSize) {
-        this(maxObjectSize, null);
+        this(maxObjectSize, ClassResolvers.cachingResolver(null));
     }
 
     /**
@@ -74,12 +74,12 @@ public class ObjectDecoder extends LengthFieldBasedFrameDecoder {
      *                       if the length of the received object is greater
      *                       than this value, {@link StreamCorruptedException}
      *                       will be raised.
-     * @param classLoader    the {@link ClassLoader} which will load the class
+     * @param classResolver    the {@link ClassResolver} which will load the class
      *                       of the serialized object
      */
-    public ObjectDecoder(int maxObjectSize, ClassLoader classLoader) {
+    public ObjectDecoder(int maxObjectSize, ClassResolver classResolver) {
         super(maxObjectSize, 0, 4, 0, 4);
-        this.classLoader = classLoader;
+        this.classResolver = classResolver;
     }
 
     @Override
@@ -92,7 +92,7 @@ public class ObjectDecoder extends LengthFieldBasedFrameDecoder {
         }
 
         return new CompactObjectInputStream(
-                new ChannelBufferInputStream(frame), classLoader).readObject();
+                new ChannelBufferInputStream(frame), classResolver).readObject();
     }
 
     @Override

src/main/java/org/jboss/netty/handler/codec/serialization/ObjectDecoderInputStream.java

@@ -119,7 +119,7 @@ public class ObjectDecoderInputStream extends InputStream implements
                     "data length too big: " + dataLen + " (max: " + maxObjectSize + ')');
         }
 
-        return new CompactObjectInputStream(in, classLoader).readObject();
+        return new CompactObjectInputStream(in, ClassResolvers.cachingResolver(classLoader)).readObject();
     }
 
     @Override