src/com/android/calendar/ExtensionsFactory.java

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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.android.calendar;

import android.content.Context;
import android.content.res.AssetManager;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;

import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

/*
 * Skeleton for additional options in the AllInOne menu.
 */
public class ExtensionsFactory {
    private static String TAG = "ExtensionsFactory";

    // Config filename for mappings of various class names to their custom implementations.
    private static String EXTENSIONS_PROPERTIES = "calendar_extensions.properties";

    private static String ALL_IN_ONE_MENU_KEY = "AllInOneMenuExtensions";

    private static Properties sProperties = new Properties();
    private static AllInOneMenuExtensionsInterface sAllInOneMenuExtensions = null;

    public static void init(AssetManager assetManager) {
        try {
            InputStream fileStream = assetManager.open(EXTENSIONS_PROPERTIES);
            sProperties.load(fileStream);
            fileStream.close();
        } catch (IOException e) {
            // No custom extensions.  Ignore.
            Log.d(TAG, "No custom extensions.", e);
        }
    }

    private static <T> T createInstance(String className) {
        try {
            Class<?> c = Class.forName(className);
            return (T) c.newInstance();
        } catch (ClassNotFoundException e) {
            Log.e(TAG, className + ": unable to create instance.", e);
        } catch (IllegalAccessException e) {
            Log.e(TAG, className + ": unable to create instance.", e);
        } catch (InstantiationException e) {
            Log.e(TAG, className + ": unable to create instance.", e);
        }
        return null;
    }

    public static AllInOneMenuExtensionsInterface getAllInOneMenuExtensions() {
        if (sAllInOneMenuExtensions == null) {
            String className = sProperties.getProperty(ALL_IN_ONE_MENU_KEY);
            if (className != null) {
                sAllInOneMenuExtensions = createInstance(className);
            } else {
                Log.d(TAG, ALL_IN_ONE_MENU_KEY + " not found in properties file.");
            }

            if (sAllInOneMenuExtensions == null) {
                sAllInOneMenuExtensions = new AllInOneMenuExtensionsInterface() {
                    @Override
                    public Integer getExtensionMenuResource(Menu menu) {
                        return null;
                    }

                    @Override
                    public boolean handleItemSelected(MenuItem item, Context context) {
                        return false;
                    }
                };
            }
        }

        return sAllInOneMenuExtensions;
    }
}