标签：很多 类型 clone time rri play vat 代码 访问权限
定义：用原型实例指定创建的种类，并且通过拷贝这些原型创建新的对象。
implement Cloneable
不支持 final
BeanUtils copy 有使用反射实现
浅拷贝：字段是值类型，逐位复制；字段是引用类型，复制引用但不复制引用对象。
深拷贝：复制引用对象, 可通过 序列化方式实现。
Resume.java
public class Resume implements Cloneable, Serializable{ private String name; private String sex; private String age; private String timeArea; private String company; private WorkExperience work; public Resume(String name) { this.name = name; work = new WorkExperience(); } public void setPersonalInfo(String sex, String age) { this.sex = sex; this.age = age; } public void setWorkExperience(String timeArea, String company) { this.timeArea = timeArea; this.company = company; //深 拷贝 work.setCompany(company); work.setWorkDate(timeArea); } public void display() { System.out.println(String.join(" ", name, sex, age)); System.out.println("工作经历：" + String.join(" ", timeArea, company )); System.out.println("workExperience：" + String.join(" ", work.getCompany(), work.getWorkDate() )); } @Override protected Object clone() throws CloneNotSupportedException { return super.clone(); }
//深拷贝 1 public Object deepClone() throws IOException, ClassNotFoundException { // 序列化 ByteArrayOutputStream bos = new ByteArrayOutputStream(); ObjectOutputStream oos = new ObjectOutputStream(bos); oos.writeObject(this); ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray()); ObjectInputStream ois = new ObjectInputStream(bis); Resume o = (Resume) ois.readObject(); return o; }
//深拷贝 2 - 常规 public Object deepClone2() throws Exception { Resume clone = (Resume) super.clone(); clone.work = (WorkExperience) this.work.clone(); return clone; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } public String getTimeArea() { return timeArea; } public void setTimeArea(String timeArea) { this.timeArea = timeArea; } public String getCompany() { return company; } public void setCompany(String company) { this.company = company; } }
WorkExperience.java
public class WorkExperience implements Serializable,Cloneable{ private String workDate; private String company; @Override protected Object clone() throws CloneNotSupportedException { return super.clone(); } public String getWorkDate() { return workDate; } public void setWorkDate(String workDate) { this.workDate = workDate; } public String getCompany() { return company; } public void setCompany(String company) { this.company = company; } }
Test.java
public class ResumeTest { public static void main(String[] args) throws Exception { //浅复制 Resume resume = new Resume("fred"); resume.setPersonalInfo("male", "29"); resume.setWorkExperience("1990-2008", "company A"); // Resume b = (Resume) resume.deepClone(); Resume b = (Resume) resume.deepClone2(); // Resume b = (Resume) resume.clone(); System.out.println("resume == b？" + (resume == b)); System.out.println("resume.getClass() == b.getClass()？" + (resume.getClass() == b.getClass())); b.setWorkExperience("2000-2015"," tongdun"); Resume c = (Resume) resume.clone(); c.setPersonalInfo("male", "30"); System.out.println("==============="); resume.display(); System.out.println("==============="); b.display(); System.out.println("==============="); c.display(); System.out.println("=====deep clone ===="); } }
结果：
===============
fred male 29
工作经历：1990-2008 company A
workExperience： tongdun 2000-2015
===============
fred male 29
工作经历：2000-2015 tongdun
workExperience： tongdun 2000-2015
===============
fred male 30
工作经历：1990-2008 company A
workExperience： tongdun 2000-2015
======deep clone========= fred male 29 工作经历：1990-2008 company A workExperience：company A 1990-2008 =============== fred male 29 工作经历：2000-2015 tongdun workExperience： tongdun 2000-2015 //使用深拷贝后 =============== fred male 30 工作经历：1990-2008 company A workExperience：company A 1990-2008 =====deep clone ====
》原型模式是在内存 二进制流的拷贝，比new 性能要好
》逃避构造函数的约束
双刃剑
》资源优化场景
- 类初始化需要消耗很多的资源
》性能和安全要求的场景
- 通过new长生一个对象需要非常 繁琐的数据准备或访问权限
》一个对象多个修改者的场景
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persistence 2. 这块语言描述总结不是很好，源于自己也还有些模糊， 待续完善。。。。。
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参考资料：
咕泡学院- 这块讲的一般
《大话设计模式》
《设计模式之蝉》
标签：很多 类型 clone time rri play vat 代码 访问权限
原文地址：https://www.cnblogs.com/idea-persistence/p/9533254.html
