made AbstractInvocationHandler that uses safer objects

core/src/main/java/org/jclouds/reflect/AbstractInvocationHandler.java

@@ -0,0 +1,58 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jclouds.reflect;
+
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.Predicates;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Iterables;
+import com.google.common.reflect.Invokable;
+
+/**
+ * Like {@link com.google.common.reflect.AbstractInvocationHandler}, except you process {@link Invokable} and
+ * {@link List} as opposed to {@link Method} and arg arrays.
+ * 
+ * @author Adrian Cole
+ * @since 1.6
+ */
+@Beta
+public abstract class AbstractInvocationHandler extends com.google.common.reflect.AbstractInvocationHandler {
+
+   /**
+    * @param args
+    *           note that this can contain nulls, as method arguments can be null.
+    * @see com.google.common.reflect.AbstractInvocationHandler#invoke(Object, Method, Object[])
+    */
+   protected abstract Object handleInvocation(Object proxy, Invokable<?, ?> method, List<Object> args) throws Throwable;
+
+   @Override
+   protected Object handleInvocation(Object proxy, Method method, Object[] argv) throws Throwable {
+      List<Object> args = Arrays.asList(argv);
+      if (Iterables.all(args, Predicates.notNull()))
+         args = ImmutableList.copyOf(args);
+      else
+         args = Collections.unmodifiableList(args);
+      return handleInvocation(proxy, Invokable.from(method), args);
+   }
+}

core/src/test/java/org/jclouds/reflect/AbstractInvocationHandlerTest.java

@@ -0,0 +1,66 @@
+/**
+ * Licensed to jclouds, Inc. (jclouds) under one or more
+ * contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  jclouds licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jclouds.reflect;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertNotNull;
+import static org.testng.Assert.assertNull;
+import static org.testng.Assert.assertTrue;
+
+import java.io.IOException;
+import java.util.List;
+
+import org.testng.annotations.Test;
+
+import com.google.common.collect.ImmutableList;
+import com.google.common.reflect.Invokable;
+import com.google.common.reflect.Reflection;
+
+/**
+ * 
+ * @author Adrian Cole
+ */
+@Test
+public class AbstractInvocationHandlerTest {
+
+   @Test(expectedExceptions = UnsupportedOperationException.class)
+   public void testNullArgsAreAllowedAndUnmodifiable() throws IOException {
+      Reflection.newProxy(Appendable.class, new AbstractInvocationHandler() {
+         protected Object handleInvocation(Object proxy, Invokable<?, ?> method, List<Object> args) throws Throwable {
+            assertNotNull(args);
+            assertNull(args.get(0));
+            args.add("foo");
+            throw new AssertionError("shouldn't be able to mutate the list!");
+         }
+      }).append(null);
+   }
+
+   @Test(expectedExceptions = UnsupportedOperationException.class)
+   public void testImmutableListWhenArgsAreNotNull() throws IOException {
+      Reflection.newProxy(Appendable.class, new AbstractInvocationHandler() {
+         protected Object handleInvocation(Object proxy, Invokable<?, ?> method, List<Object> args) throws Throwable {
+            assertNotNull(args);
+            assertTrue(args instanceof ImmutableList);
+            assertEquals(args.get(0), "foo");
+            args.add("bar");
+            throw new AssertionError("shouldn't be able to mutate the list!");
+         }
+      }).append("foo");
+   }
+}