设计模式课程 设计模式精讲 9-4 原型模式源码解析

1　　　　源码解析

1.1　　源码解析1（java.lang.Object对象）

1.2　　源码解析2（ArrayList实现克隆）

1.3　　源码解析3（mybaties 的cacheKey）

1　　　　源码解析

1.1　　源码解析1（java.lang.Object对象）

//native 调用非java代码接口 
 protected native Object clone() throws CloneNotSupportedException;

1.2　　源码解析2（ArrayList实现克隆）

public class ArrayList<E> extends AbstractList<E>
        implements List<E>, RandomAccess, Cloneable, java.io.Serializable{

/**
     * Returns a shallow copy of this <tt>ArrayList</tt> instance.  (The
     * elements themselves are not copied.)
     *
     * @return a clone of this <tt>ArrayList</tt> instance
     */
    public Object clone() {
        try {
            @SuppressWarnings("unchecked")
                ArrayList<E> v = (ArrayList<E>) super.clone();
            v.elementData = Arrays.copyOf(elementData, size);
            v.modCount = 0;
            return v;
        } catch (CloneNotSupportedException e) {
            // this shouldn't happen, since we are Cloneable
            throw new InternalError();
        }
    }

}

1.3　　源码解析3（mybaties 的cacheKey）

/**
 *    Copyright 2009-2016 the original author or authors.
 *
 *    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 org.apache.ibatis.cache;

import java.io.Serializable;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.List;

/**
 * @author Clinton Begin
 */
public class CacheKey implements Cloneable, Serializable {
 
 @Override
  public CacheKey clone() throws CloneNotSupportedException {
    CacheKey clonedCacheKey = (CacheKey) super.clone();
    clonedCacheKey.updateList = new ArrayList<Object>(updateList);
    return clonedCacheKey;
  }

}