文章目录
- 一、概念
- 1、概念对比
- 2、常用API整理
- 二、浅拷贝
- 1、实体类
- 2、Map类型
- 3、数组
- 4、集合
- 5、JSONObject
- 6、JsonArray
- 三、深拷贝
- 四、XMind文件
一、概念
1、概念对比
简单地址值复制
内容完全一致，只是由2个变量值，进行取值使用(user01、user02)。
User user01 = new User();
User user02 = user01;覆盖子集的地址值的复制
借助一定的API，表明子集的类型。能够实现对子集地址值(obj02)的覆盖。当子集中obj02数据变更，则复制后值也变更。
完全的深拷贝
目前只能借助格式化来实现，可以采用流进行复制，也可以借助JSON格式化来实现。
2、常用API整理
二、浅拷贝
1、实体类
核心API
import org.springframework.beans.BeanUtils;
BeanUtils.copyProperties(user01, user02);代码:
User user01 = new User("张三", 18, "北京");
User user02 = new User();
BeanUtils.copyProperties(user01, user02);
System.out.println(user01.equals(user02));
System.out.println(user01);
System.out.println(user02);
System.out.println("====更新值====");
user01.setName("王五");
System.out.println(user01);
System.out.println(user02);结果：
true
User(name=张三, age=18, address=北京)
User(name=张三, age=18, address=北京)
====更新值====
User(name=王五, age=18, address=北京)
User(name=张三, age=18, address=北京)2、Map类型
核心API
HashMap<String, String> newMap01 = new HashMap<>(hashMap);
newMap02.putAll(hashMap);代码：
HashMap<String, String> hashMap = new HashMap<>();
hashMap.put("key01", "value01");
hashMap.put("key02", "value02");
hashMap.put("key03", "value03");
// 浅拷贝
HashMap<String, String> newMap01 = new HashMap<>(hashMap);
HashMap<String, String> newMap02 = new HashMap<>();
newMap02.putAll(hashMap);
System.out.println(hashMap);
System.out.println(newMap01);
System.out.println(newMap02);结果：
{key03=value03, key02=value02, key01=value01}
{key03=value03, key02=value02, key01=value01}
{key03=value03, key02=value02, key01=value01}
{level02={key01=value01}}
{level02={key01=value01}}反例(不支持深拷贝)：
// 反例
HashMap<String, Map> level01 = new HashMap<>();
HashMap<String, String> level02 = new HashMap<>();
level02.put("key01", "value01");
level01.put("level02", level02);
HashMap<String, Map> newLevel = new HashMap<>(level01);
System.out.println(level01);
System.out.println(newLevel);
System.out.println("更新值后");
level02.put("key01", "======");
System.out.println(level01);
System.out.println(newLevel);{level02={key01=value01}}
{level02={key01=======}}3、数组
核心API
int[] arr2 = Arrays.copyOf(arr1, arr1.length);// 复制数组解析： （原数组，从原数组的起始位置，目标数组，目标数组的起始位置，要复制的数组长度）
System.arraycopy(arr1, 0, arr3, 0, arr1.length);代码：
int[] arr1 = {1, 2, 3, 4, 5};
int[] arr2 = Arrays.copyOf(arr1, arr1.length);
int[] arr3 = new int[arr1.length];
// 复制数组解析： （原数组，从原数组的起始位置，目标数组，目标数组的起始位置，要复制的数组长度）
System.arraycopy(arr1, 0, arr3, 0, arr1.length);
System.out.println(JSON.toJSONString(arr1));
System.out.println(JSON.toJSONString(arr2));
System.out.println(JSON.toJSONString(arr3));结果：
[1,2,3,4,5]
[1,2,3,4,5]
[1,2,3,4,5]4、集合
核心API
// 复制对象值的拷贝
import cn.hutool.core.bean.BeanUtil;
List<User> arrayLists = BeanUtil.copyToList(users, User.class);
浅拷贝：
users03.addAll(users);
ArrayList<User> users04 = new ArrayList<>(users);代码：
User user03 = new User("张三", 18, "北京");
User user04 = new User("李四", 19, "天津");
ArrayList<User> users = new ArrayList<>();
users.add(user03);
users.add(user04);
List<User> arrayLists = BeanUtil.copyToList(users, User.c
ArrayList<User> users03 = new ArrayList<>();
users03.addAll(users);
ArrayList<User> users04 = new ArrayList<>(users);
// 打印初始值
System.out.println(JSON.toJSONString(users));
System.out.println(JSON.toJSONString(arrayLists));
System.out.println(JSON.toJSONString(users03));
System.out.println(JSON.toJSONString(users04));
System.out.println("====");
// 更新某个对象值
user03.setName("ddddd");
System.out.println(JSON.toJSONString(users));
System.out.println(JSON.toJSONString(arrayLists));
System.out.println(JSON.toJSONString(users03));
System.out.println(JSON.toJSONString(users04));结果：
[{"address":"北京","age":18,"name":"张三"},{"address":"天津","age":19,"name":"李四"}]
[{"address":"北京","age":18,"name":"张三"},{"address":"天津","age":19,"name":"李四"}]
[{"address":"北京","age":18,"name":"张三"},{"address":"天津","age":19,"name":"李四"}]
[{"address":"北京","age":18,"name":"张三"},{"address":"天津","age":19,"name":"李四"}]
====
[{"address":"北京","age":18,"name":"ddddd"},{"address":"天津","age":19,"name":"李四"}]
[{"address":"北京","age":18,"name":"张三"},{"address":"天津","age":19,"name":"李四"}]
[{"address":"北京","age":18,"name":"ddddd"},{"address":"天津","age":19,"name":"李四"}]
[{"address":"北京","age":18,"name":"ddddd"},{"address":"天津","age":19,"name":"李四"}]5、JSONObject
核心API
obj02.putAll(obj01);代码：
JSONObject one = new JSONObject();
one.put("one", "fish");
JSONObject two = new JSONObject();
two.putAll(one);
// 打印初始值
System.out.println("init: one: " + one.toString());
System.out.println("init: two: " + two.toString());
// 更改值
one.put("one", "fish=======");
System.out.println("init: one: " + one.toString());
System.out.println("init: two: " + two.toString());2层子对象
JSONObject obj01 = new JSONObject();
JSONObject obj01_01 = new JSONObject();
obj01.put("dd111", obj01_01);
obj01_01.put("key01", "value01");
JSONObject obj02 = new JSONObject();
obj02.putAll(obj01);
// 打印初始值
System.out.println(obj01);
System.out.println(obj02);
// 更改值
obj01_01.put("dd111", "value01=============");
System.out.println(obj01);
System.out.println(obj02);结果：
init: one: {"one":"fish"}
init: two: {"one":"fish"}
init: one: {"one":"fish======="}
init: two: {"one":"fish"}
============================================================
{"dd111":{"key01":"value01"}}
{"dd111":{"key01":"value01"}}
{"dd111":{"key01":"value01","dd111":"value01============="}}
{"dd111":{"key01":"value01","dd111":"value01============="}}6、JsonArray
核心API
JSONArray jsonArray02 = (JSONArray) jsonArray01.clone();
jsonArray03.addAll(jsonArray01);代码：
JSONArray jsonArray01 = new JSONArray();
jsonArray01.add("test01");
jsonArray01.add("test02");
jsonArray01.add("test03");
JSONArray jsonArray02 = (JSONArray) jsonArray01.clone();
JSONArray jsonArray03 = new JSONArray();
jsonArray03.addAll(jsonArray01);
// 打印初始值
System.out.println(jsonArray01);
System.out.println(jsonArray02);
System.out.println(jsonArray03);子集值，更新
JSONArray jsonArray01 = new JSONArray();
jsonArray01.add("test01");
jsonArray01.add("test02");
jsonArray01.add("test03");
JSONObject one = new JSONObject();
one.put("one", "fish");
jsonArray01.add(one);
JSONArray jsonArray05 = (JSONArray) jsonArray01.clone()
JSONArray jsonArray06 = new JSONArray();
jsonArray06.addAll(jsonArray01);
// 打印初始值
System.out.println(jsonArray01);
System.out.println(jsonArray05);
System.out.println(jsonArray06);
// 值更新
one.put("two", "two");
System.out.println(jsonArray01);
System.out.println(jsonArray05);
System.out.println(jsonArray06);结果：
["test01","test02","test03"]
["test01","test02","test03"]
["test01","test02","test03"]
---
["test01","test02","test03",{"one":"fish"}]
["test01","test02","test03",{"one":"fish"}]
["test01","test02","test03",{"one":"fish"}]
["test01","test02","test03",{"one":"fish","two":"two"}]
["test01","test02","test03",{"one":"fish","two":"two"}]
["test01","test02","test03",{"one":"fish","two":"two"}]三、深拷贝
实体类
User user = new User();
String s = JSON.toJSONString(user);
User userClone = JSON.parseObject(s, User.class);Map
HashMap<String, String> hashMap = new HashMap<>();
String s1 = JSON.toJSONString(hashMap);
HashMap hashMap1 = JSON.parseObject(s, HashMap.class);List集合
ArrayList<User> users = new ArrayList<>();
String s2 = JSON.toJSONString(users);
ArrayList arrayList = JSON.parseObject(s2, ArrayList.class);JSONObject
JSONObject jsonObject = new JSONObject();
String s3 = jsonObject.toJSONString();
JSONObject jsonObject1 = JSON.parseObject(s3, JSONObject.class);JSONArray
JSONArray jsonArray = new JSONArray();
String s4 = jsonArray.toJSONString();
JSONArray jsonArray1 = JSON.parseObject(s4, JSONArray.class);四、XMind文件
