com.shipdream.lib.android.mvc.MvcBean Maven / Gradle / Ivy

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/*
 * Copyright 2016 Kejun Xia
 *
 * 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.shipdream.lib.android.mvc;

import com.shipdream.lib.poke.util.ReflectUtils;

public abstract class MvcBean {
    private MODEL model;

    /**
     * Bind model to MvcBean
     * @param model non-null model
     * @throws IllegalArgumentException thrown when null is being bound
     */
    public void bindModel(MODEL model) {
        if (model == null) {
            throw new IllegalArgumentException("Can't bind null model explicitly.");
        } else {
            this.model = model;
        }
    }

    /**
     * Called when the MvcBean is injected for the first time or restored when a new instance of
     * this MvcBean needs to be instantiated.
     *
     * The model of the MvcBean will be instantiated by model's default no-argument constructor.
     * However, if the MvcBean needs to be restored, a new instance of model restored by
     * {@link #restoreModel(Object)} will replace the model created by this method.
     */
    public void onConstruct() {
        model = instantiateModel();
    }

    private MODEL instantiateModel() {
        Class type = modelType();
        if (type == null) {
            return null;
        } else {
            try {
                return new ReflectUtils.newObjectByType<>(type).newInstance();
            } catch (Exception e) {
                throw new RuntimeException("Fail to instantiate model by its default constructor");
            }
        }
    }

    /**
     * Called when the MvcBean is disposed. This occurs when the MvcBean is de-referenced and
     * not retained by any other objects.
     */
    public void onDisposed() {
    }

    /**
     * Model represents the state of this MvcBean.
     * @return Null if the MvcBean doesn't need to get its model saved and restored automatically.
     */
    public MODEL getModel() {
        return model;
    }

    /**
     * Provides the type class of the model.
     * @return Implementing class should return the type class of the model that will be used by
     * this MvcBean to instantiate its model in {@link #onConstruct()} and restores model in
     * {@link #restoreModel(Object)}. Returning null is allowed which means this MvcBean doesn't
     * have a model needs to be automatically saved and restored.
     */
    public abstract Class modelType();

    /**
     * Restores the model of this MvcBean.
     * 
     * Note that when {@link #modelType()} returns null, this method will have no effect.
     * 
     *
     * @param restoredModel The restored model by {@link ModelKeeper} that will be rebound to the
     *                      MvcBean.
     */
    public void restoreModel(MODEL restoredModel) {
        if (modelType() != null) {
            this.model = restoredModel;
            onRestored();
        }
    }

    /**
     * Called after {@link #restoreModel(Object)} is called only when {@link #modelType()} returns
     * a non-null type class.
     */
    public void onRestored() {
    }
}