android/sdk/src/main/java/com/taobao/weex/utils/WXInterception.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF 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 com.taobao.weex.utils;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class WXInterception {

  private WXInterception() {
  }

  @SuppressWarnings("unchecked")
  public static <T> T proxy(final Object delegatee, final Class<T> interface_class, final InterceptionHandler<T> handler) throws IllegalArgumentException {
    if (delegatee instanceof Intercepted) {
      return (T) delegatee;
    }
    handler.setDelegate((T) delegatee);
    return (T) Proxy.newProxyInstance(WXInterception.class.getClassLoader(), new Class<?>[]{interface_class, Intercepted.class}, handler);
  }

  @SuppressWarnings("unchecked")
  public static <T> T proxy(final Object delegatee, final InterceptionHandler<T> handler, final Class<?>... interfaces) throws IllegalArgumentException {
    //if (Proxy.isProxyClass(delegatee.getClass())) return (T) delegatee;
    handler.setDelegate((T) delegatee);
    return (T) Proxy.newProxyInstance(WXInterception.class.getClassLoader(), interfaces, handler);
  }

  private interface Intercepted {

  }        // A mark to identify our proxy class

  /**
   * Derive this class and override {@link #invoke(Object, Method, Object[])} to implement an
   * interception handler.
   */
  public abstract static class InterceptionHandler<T> implements InvocationHandler {

    private T mDelegate;

    /**
     * Derived class should override this method and call <code>super.invoke(...)</code> to delegate the
     * procedure to original delegate instance if needed.
     *
     * @param proxy is ignored, instead the actual delegate instance will be used to invoke this method on.
     */
    @Override
    public Object invoke(final Object proxy, final Method method, final Object[] args) throws Throwable {
      try {
        return method.invoke(delegate(), args);
      } catch (IllegalArgumentException e) {/* Should never happen */
        WXLogUtils.e("", e);
        return null;
      } catch (IllegalAccessException e) {/* Should never happen */
        WXLogUtils.e("", e);
        return null;
      } catch (InvocationTargetException e) {
        throw e.getTargetException();
      }
    }

    protected T delegate() {
      return mDelegate;
    }

    void setDelegate(final T delegate) {
      mDelegate = delegate;
    }
  }
}