[jboss-svn-commits] JBoss Common SVN: r3677 - shrinkwrap/trunk/api/src/main/java/org/jboss/shrinkwrap/api.

[jboss-svn-commits at lists.jboss.org]

Author: aslak
Date: 2009-11-12 05:01:06 -0500 (Thu, 12 Nov 2009)
New Revision: 3677

Added:
   shrinkwrap/trunk/api/src/main/java/org/jboss/shrinkwrap/api/ReflectionUtil.java
Log:
SHRINKWRAP-57 SHRINKWRAP-74 Common util for creating new instance of a class based on string name

Added: shrinkwrap/trunk/api/src/main/java/org/jboss/shrinkwrap/api/ReflectionUtil.java
===================================================================
--- shrinkwrap/trunk/api/src/main/java/org/jboss/shrinkwrap/api/ReflectionUtil.java	                        (rev 0)
+++ shrinkwrap/trunk/api/src/main/java/org/jboss/shrinkwrap/api/ReflectionUtil.java	2009-11-12 10:01:06 UTC (rev 3677)
@@ -0,0 +1,103 @@
+/*
+ * JBoss, Home of Professional Open Source
+ * Copyright 2009, Red Hat Middleware LLC, and individual contributors
+ * by the @authors tag. See the copyright.txt in the distribution for a
+ * full listing of individual contributors.
+ *
+ * Licensed 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.jboss.shrinkwrap.api;
+
+import java.lang.reflect.Constructor;
+
+import com.sun.xml.internal.txw2.IllegalAnnotationException;
+
+/**
+ * ReflectionUtil
+ * 
+ * Helper class for creating new instances of a class
+ *
+ * @author <a href="mailto:aslak at conduct.no">Aslak Knutsen</a>
+ * @version $Revision: $
+ */
+final class ReflectionUtil
+{
+   /**
+    * Create a new instance by finding a constructor that matches the argumentTypes signature 
+    * using the arguments for instantiation.
+    * 
+    * @param className Full classname of class to create
+    * @param argumentTypes The constructor argument types
+    * @param arguments The constructor arguments
+    * @return a new instance
+    * @throws IllegalArgumentException if className is null
+    * @throws IllegalArgumentException if argumentTypes is null
+    * @throws IllegalArgumentException if arguments is null
+    * @throws RuntimeException if any exceptions during creation
+    */
+   public static Object createInstance(String className, Class<?>[] argumentTypes, Object[] arguments) 
+   {
+      if(className == null) 
+      {
+         throw new IllegalArgumentException("ClassName must be specified");
+      }
+      if(argumentTypes == null) 
+      {
+         throw new IllegalAnnotationException("ArgumentTypes must be specified. Use empty array if no arguments");
+      }
+      if(arguments == null) 
+      {
+         throw new IllegalAnnotationException("Arguments must be specified. Use empty array if no arguments");
+      }
+      try 
+      {
+         Class<?> implClass = loadClass(className); 
+         Constructor<?> constructor = findConstructor(implClass, argumentTypes);
+         return (Path)constructor.newInstance(arguments);
+      }
+      catch (Exception e) 
+      {
+         throw new RuntimeException(
+               "Could not create new instance of " + className + ", missing package from classpath?", e);
+      } 
+   }
+
+   //-------------------------------------------------------------------------------------||
+   // Class Members - Internal Helpers ---------------------------------------------------||
+   //-------------------------------------------------------------------------------------||
+   
+   /**
+    * Load the specified class using Thread Current Class Loader in a privileged block. 
+    */
+   private static Class<?> loadClass(String archiveImplClassName) throws Exception 
+   {
+      return SecurityActions.getThreadContextClassLoader().loadClass(archiveImplClassName);
+   }
+   
+   /**
+    * Find a constructor that match the signature of given argumentTypes.
+    */
+   private static Constructor<?> findConstructor(Class<?> archiveImplClazz, Class<?>... argumentTypes) throws Exception 
+   {
+      return archiveImplClazz.getConstructor(argumentTypes);
+   }
+
+   //-------------------------------------------------------------------------------------||
+   // Constructor ------------------------------------------------------------------------||
+   //-------------------------------------------------------------------------------------||
+
+   /**
+    * No instantiation
+    */
+   private ReflectionUtil()
+   {
+   }
+}