拷貝，顧名思義就是復(fù)制，分配新的內(nèi)存，產(chǎn)生新的對(duì)象，與new關(guān)鍵字類似。然而，拷貝中存在部分隱匿的差別，需要我們細(xì)細(xì)查看

// 學(xué)士：姓名 年齡 信息
public class Bachelor {
    private String name;
    private int age;
    private Info info;
    
    public Bachelor(String name,int age,Info info){
        this.name = name;
        this.age = age;
        this.info = info;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Info getInfo() {
        return info;
    }
    public void setInfo(Info info) {
        this.info = info;
    }   
}
// 信息：技能　項(xiàng)目　
class Info{
    private String level;
    private Project project;
    
    public Info(String level,Project project){
        this.level = level;
        this.project = project;
    }
    public Project getProject() {
        return project;
    }
    public void setProject(Project project) {
        this.project = project;
    }
}
// 項(xiàng)目：項(xiàng)目名稱
class Project{
    private String projectName;
    
    public Project(String projectName){
        this.projectName = projectName;
    }
}

1. 引用拷貝
   不同引用指向相同地址，并不分配新的內(nèi)存空間；

    // 測試代碼
    Project project = new Project("myApp");
    Info info = new Info("A",project);
    Bachelor bachelorOne = new Bachelor("Cheng",23,info);
    
    Bachelor bachelorTwo = bachelorOne;
    System.out.println(bachelorOne);
    System.out.println(bachelorTwo);

// 打印出相同的地址
javaBasic.Bachelor@15db9742
javaBasic.Bachelor@15db9742

2. 對(duì)象拷貝

// 實(shí)現(xiàn)Cloneable接口，復(fù)寫clone()方法
public class Bachelor implements Cloneable{
    @Override
    protected Object clone() throws CloneNotSupportedException {
        Bachelor newBachelor = (Bachelor) super.clone();
        return newBachelor;
    }
}

    // 測試代碼
    Project project = new Project("myApp");
    Info info = new Info("A",project);
    Bachelor bachelorOne = new Bachelor("Cheng",23,info);

    Bachelor bachelorTwo = (Bachelor) bachelorOne.clone();
    System.out.println(bachelorOne);
    System.out.println(bachelorTwo);
    System.out.println(bachelorOne.getName() == bachelorTwo.getName());

// 打印出不同地址，且name引用相同
javaBasic.Bachelor@15db9742
javaBasic.Bachelor@6d06d69c
true

• 淺拷貝
  如上面測試代碼，分配新的內(nèi)存，創(chuàng)建新對(duì)象，但是name屬性卻存在相同的引用，即拷貝主對(duì)象，卻不拷貝主對(duì)象里面的對(duì)象；
  如何實(shí)現(xiàn)name屬性的拷貝呢？

    // 重新生成name對(duì)象
    @Override
    protected Object clone() throws CloneNotSupportedException {
        Bachelor newBachelor = (Bachelor) super.clone();
        newBachelor.name = new String(this.name);
        return newBachelor;
    }

按照此種邏輯，info對(duì)象也是淺拷貝，如何實(shí)現(xiàn)主對(duì)象中對(duì)象的拷貝呢？

// 類實(shí)現(xiàn)Cloneable接口，復(fù)寫clone方法
// 在clone()方法中，實(shí)現(xiàn)主對(duì)象內(nèi)對(duì)象的重新生成
public class Bachelor implements Cloneable{
    @Override
    protected Object clone() throws CloneNotSupportedException {
        Bachelor newBachelor = (Bachelor) super.clone();
        newBachelor.name = new String(this.name);
        newBachelor.info = (Info) this.info.clone();
        return newBachelor;
    }
}

class Info implements Cloneable{
    @Override
    protected Object clone() throws CloneNotSupportedException {
        Info newInfo = (Info) super.clone();
        // 將level屬性和project方法均重新生成
        newInfo.level = new String(this.level);
        newInfo.project = (Project) this.project.clone();
        return newInfo;
    }

class Project implements Cloneable{
    @Override
    protected Object clone() throws CloneNotSupportedException {
        // TODO Auto-generated method stub
        return (Project) super.clone();
    }
}

// 測試代碼
    Project project = new Project("myApp");
    Info info = new Info("A",project);
    Bachelor bachelorOne = new Bachelor("Cheng",23,info);
        
    Bachelor bachelorTwo = (Bachelor) bachelorOne.clone();
    System.out.println(bachelorOne);
    System.out.println(bachelorTwo);
    System.out.println(bachelorOne.getName() == bachelorTwo.getName());
    System.out.println(bachelorTwo.getInfo() == bachelorOne.getInfo());
    System.out.println(bachelorTwo.getInfo().getProject() == bachelorOne.getInfo().getProject());

// 實(shí)現(xiàn)主對(duì)象內(nèi)部所有對(duì)象的拷貝
javaBasic.Bachelor@15db9742
javaBasic.Bachelor@6d06d69c
false
false
false

• 深拷貝
  實(shí)現(xiàn)主對(duì)象全部結(jié)構(gòu)的拷貝，包括主對(duì)象中的對(duì)象；