defaultconstructionproxyfactory.java

Guice是轻量级的依赖注入框架。简而言之

/**
 * Copyright (C) 2006 Google Inc.
 *
 * 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 com.google.inject;

import com.google.inject.util.GuiceFastClass;
import com.google.inject.util.Objects;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Modifier;
import net.sf.cglib.reflect.FastClass;
import net.sf.cglib.reflect.FastConstructor;

/**
 * Default {@link ConstructionProxyFactory} implementation. Simply invokes the
 * constructor. Can be reused by other {@code ConstructionProxyFactory}
 * implementations.
 *
 * @author [e-mail] (Bob Lee)
 */
class DefaultConstructionProxyFactory implements ConstructionProxyFactory {

  public <T> ConstructionProxy<T> get(final Constructor<T> constructor) {
    // We can't use FastConstructor if the constructor is private or protected.
    if (Modifier.isPrivate(constructor.getModifiers())
        || Modifier.isProtected(constructor.getModifiers())) {
      constructor.setAccessible(true);
      return new ConstructionProxy<T>() {
        public T newInstance(Object... arguments) throws
            InvocationTargetException {
          Objects.assertNoNulls(arguments);
          try {
            return constructor.newInstance(arguments);
          }
          catch (InstantiationException e) {
            throw new RuntimeException(e);
          }
          catch (IllegalAccessException e) {
            throw new AssertionError(e);
          }
        }
      };
    }

    Class<T> classToConstruct = constructor.getDeclaringClass();
    FastClass fastClass = GuiceFastClass.create(classToConstruct);
    final FastConstructor fastConstructor
        = fastClass.getConstructor(constructor);
    return new ConstructionProxy<T>() {
      @SuppressWarnings("unchecked")
      public T newInstance(Object... arguments)
          throws InvocationTargetException {
        Objects.assertNoNulls(arguments);
        return (T) fastConstructor.newInstance(arguments);
      }
    };
  }
}