java集合深度拷贝---流不需要关闭

参考https://www.iteye.com/blog/bijian1013-2358367  里边包含各种浅拷贝，一般场景用Collections.copy(destList, srcList); 确实能实现，其实是浅拷贝
public static void main(String[] args) {
    List list = Lists.newArrayList();
    JSONObject obj = new JSONObject();
    obj.put("sec1", "sec1");
    obj.put("sec2", "sec2");
    list.add(obj);
    JSONObject obj1 = new JSONObject();
    obj1.put("sec3", "sec3");
    obj1.put("sec4", "sec4");
    list.add(obj1);
    for (int i = 0; i < 3; i++) {
        //List list1 = Lists.newArrayList(list);
        //Collections.copy(list1, list);
        List list1 = (List) deepCopy(list);
        for (int j = 0; j < list1.size(); j++) {
            JSONObject jsonObject = list1.get(j);
            jsonObject.put("sec2", "des2");
            System.out.println("目标数组元素:" + JSONArray.parseArray(JSONObject.toJSONString(list1)));
        }
    }
    System.out.println("源数组元素:" + JSONArray.parseArray(JSONObject.toJSONString(list)));
}

public static List deepCopy(List src) {
    List dest = null;
    try {
        ByteArrayOutputStream byteOut = new ByteArrayOutputStream();
        ObjectOutputStream out = new ObjectOutputStream(byteOut);
        out.writeObject(src);
        ByteArrayInputStream byteIn = new ByteArrayInputStream(byteOut.toByteArray());
        ObjectInputStream in = new ObjectInputStream(byteIn);
        dest = (List) in.readObject();
        // in.close();
        // out.close();
    } catch (IOException | ClassNotFoundException e) {
        e.printStackTrace();
    }
    return dest;
}

 

如果为注释掉的写法的话运行结果为

目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
源数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]

用后边的这种流的方式才是深度拷贝（使用序列化方法）

目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec4":"sec4","sec3":"sec3"}]
目标数组元素:[{"sec2":"des2","sec1":"sec1"},{"sec2":"des2","sec4":"sec4","sec3":"sec3"}]
源数组元素:[{"sec2":"sec2","sec1":"sec1"},{"sec4":"sec4","sec3":"sec3"}]

注意  引入的为

   com.alibaba
   fastjson
   1.2.58

这个ByteArrayOutputStream 流没有关闭，查看了源码，这个类的close方法是空实现。由此可见，这个流是不需要关闭的，正常的流务必手动关闭。