src/main/java/com/github/mottox/util/bean/BeanUtils.java

/*
 * Copyright (c) 2017 Robin Wang
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.github.mottox.util.bean;

import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;

import net.sf.cglib.beans.BeanCopier;

/**
 * A wrapper util class for {@link BeanCopier}, providing convenience and high-performance conversion between JavaBeans.
 *
 * @author Robin Wang
 */
public class BeanUtils {

    /**
     * The map to store {@link BeanCopier} of source type and class type for conversion.
     */
    private static final Map<String, BeanCopier> BEAN_COPIER_MAP = new ConcurrentHashMap<>();

    /**
     * Private constructor.
     */
    private BeanUtils() {
    }

    /**
     * Copy the property values of the given source bean into the target bean.
     *
     * @param source the source bean
     * @param target the target bean
     *
     * @see BeanCopier
     */
    public static void copyProperties(Object source, Object target) {
        Objects.requireNonNull(source, "source must not be null");
        Objects.requireNonNull(target, "target must not be null");

        BeanCopier beanCopier = getBeanCopier(source.getClass(), target.getClass());
        beanCopier.copy(source, target, null);
    }

    /**
     * Convert the given source bean to a target bean of specified type.
     *
     * @param source the source bean
     * @param clazz  the class of target bean
     * @param <T>    the type of target bean
     *
     * @return the target bean of type <code>T</code>
     */
    public static <T> T convert(Object source, Class<T> clazz) {
        // Initialize a new instance of the target type.
        T result;
        try {
            result = clazz.newInstance();
        } catch (ReflectiveOperationException e) {
            throw new RuntimeException("fail to create instance of type" + clazz.getCanonicalName(), e);
        }

        copyProperties(source, result);
        return result;
    }

    /**
     * Get the {@link BeanCopier} of source class and target class.
     * Create a new one if it is not contained in <code>BEAN_COPIER_MAP</code>.
     *
     * @param source the source class
     * @param target the target class
     *
     * @return the bean copier of source class and target class
     */
    private static BeanCopier getBeanCopier(Class<?> source, Class<?> target) {
        String key = generateKey(source, target);
        return BEAN_COPIER_MAP.computeIfAbsent(key, x -> BeanCopier.create(source, target, false));
    }

    /**
     * Get key of <code>BEAN_COPIER_MAP</code> by source class and target class.
     *
     * @param source the source class
     * @param target the target class
     *
     * @return the key of <code>BEAN_COPIER_MAP</code> by source class and target class
     */
    private static String generateKey(Class<?> source, Class<?> target) {
        return source.getCanonicalName().concat(target.getCanonicalName());
    }

}