InstanceCreationUtils.java

/*
 * Copyright 2013 Chris Banes
 *
 * 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.roboo.like.google.abs.ptr;

import java.lang.reflect.Constructor;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import com.roboo.like.google.views.helper.PullToRefreshHelper;

import android.content.Context;
import android.util.Log;
import android.view.View;

public class InstanceCreationUtils
{

	private static final String LOG_TAG = "InstanceCreationUtils";

	private static final Class<?>[] VIEW_DELEGATE_CONSTRUCTOR_SIGNATURE = new Class[] {};
	private static final Class<?>[] TRANSFORMER_CONSTRUCTOR_SIGNATURE = new Class[] {};

	private static final HashMap<Class, Class> BUILT_IN_DELEGATES;

	static
	{
		BUILT_IN_DELEGATES = new HashMap<Class, Class>();
		BUILT_IN_DELEGATES.put(AbsListViewDelegate.SUPPORTED_VIEW_CLASS, AbsListViewDelegate.class);

	}
	/**可进行刷新View的代理*/
	public static PullToRefreshHelper.ViewDelegate getBuiltInViewDelegate(final View view)
	{
		final Set<Map.Entry<Class, Class>> entries = BUILT_IN_DELEGATES.entrySet();
		for (final Map.Entry<Class, Class> entry : entries)
		{
			if (entry.getKey().isInstance(view))
			{
				return InstanceCreationUtils.newInstance(view.getContext(), entry.getValue(), VIEW_DELEGATE_CONSTRUCTOR_SIGNATURE, null);
			}
		}
		return null;
	}

	static <T> T instantiateViewDelegate(Context context, String className, Object[] arguments)
	{
		try
		{
			Class<?> clazz = context.getClassLoader().loadClass(className);
			return newInstance(context, clazz, VIEW_DELEGATE_CONSTRUCTOR_SIGNATURE, arguments);
		}
		catch (Exception e)
		{
			Log.w(LOG_TAG, "Cannot instantiate class: " + className, e);
		}
		return null;
	}

	static <T> T instantiateTransformer(Context context, String className, Object[] arguments)
	{
		try
		{
			Class<?> clazz = context.getClassLoader().loadClass(className);
			return newInstance(context, clazz, TRANSFORMER_CONSTRUCTOR_SIGNATURE, arguments);
		}
		catch (Exception e)
		{
			Log.w(LOG_TAG, "Cannot instantiate class: " + className, e);
		}
		return null;
	}

	private static <T> T newInstance(Context context, Class clazz, Class[] constructorSig, Object[] arguments)
	{
		try
		{
			Constructor<?> constructor = clazz.getConstructor(constructorSig);
			return (T) constructor.newInstance(arguments);
		}
		catch (Exception e)
		{
			Log.w(LOG_TAG, "Cannot instantiate class: " + clazz.getName(), e);
		}
		return null;
	}

}