java設計模式--原型模式

時間 2019-12-14

標籤 java 設計模式原型欄目 Java 简体版

原文原文鏈接

　　原型模式：用原型實例指定建立對象的種類，並經過拷貝這些原型建立新的對象。通俗來講就是克隆一個對象，並且不用知道建立對象的細節，而後對這個對象進行自定義操做。首先，咱們先看一下下面的這個例子。性能

//公司類
public class Company {

    private String level;
    private Long workYears;

    public String getLevel() {
        return level;
    }

    public void setLevel(String level) {
        this.level = level;
    }

    public Long getWorkYears() {
        return workYears;
    }

    public void setWorkYears(Long workYears) {
        this.workYears = workYears;
    }
}


//實現Cloneable接口的People類（原型實例）
public class People implements Cloneable {
    private String name;
    private Long age;
    private String gender;
    //公司屬性，沒有實現Cloneable接口
    private Company company;

    public String getName() {
        return name;
    }

    public People() {
        //在初始People類的同時建立company實例
        this.company = new Company();
    }

    public void setName(String name) {
        this.name = name;
    }

    public Long getAge() {
        return age;
    }

    public void setAge(Long age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Company getCompany() {
        return company;
    }

    public void setCompany(String level,Long workYears) {
        //給company的屬性賦值
        this.company.setLevel(level);
        this.company.setWorkYears(workYears);
    }

    //Clone()方法，clone people類
    public Object Clone() {
        Object clone = null;
        try {
             clone = super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return (People) clone;
    }

    public void show() {
        System.out.println("name:" + name + ",age:" + age + ",gender" + gender);
        System.out.println("name:" + name + ",level:" + company.getLevel() + ",workYears:" + company.getWorkYears());
    }
}


public class Test {
    public static void main(String[] args) {
　　　　  //原型實例對象
        People people = new People();
        people.setName("zhangsan");
        people.setAge(23L);
        people.setGender("man");
        people.setCompany("A7",3L);

        //克隆對象1，修改age，gender屬性
        People clone1 = (People)people.Clone();
        clone1.setAge(25L);
        clone1.setGender("woman");

        //克隆對象2，修改age，company屬性
        People clone2 = (People)people.Clone();
        clone2.setAge(26L);
        clone2.setCompany("A8",4L);
        people.show();
        clone1.show();
        clone2.show();
    }

}

獲得的結果爲：this

name:zhangsan,age:23,genderman
name:zhangsan,level:A8,workYears:4spa

name:zhangsan,age:25,genderwoman
name:zhangsan,level:A8,workYears:4code

name:zhangsan,age:26,genderman
name:zhangsan,level:A8,workYears:4對象

　　咱們能夠看到值類型的字段都會拷貝一份新的出來，對他們修改也不會對被克隆對象的值進行修改，可是若是字段是引用類型，則拷貝引用，但不復制引用的對象，這樣的話若是咱們對引用類型的字段company進行修改就會致使顯示的永遠是最後一次修改的值，由於拷貝出的三個引用指向一個對象，這就是淺拷貝。blog

　　那麼若是咱們想把引用類型的字段也拷貝一份出來呢，那麼咱們就須要把引用類型也實現Cloneable接口，並重寫Clone()方法，而且把引用類型的屬性再拷貝一遍，代碼以下：接口

public class Company implements Cloneable{

    private String level;
    private Long workYears;

    public String getLevel() {
        return level;
    }

    public void setLevel(String level) {
        this.level = level;
    }

    public Long getWorkYears() {
        return workYears;
    }

    public void setWorkYears(Long workYears) {
        this.workYears = workYears;
    }

    //Clone()方法，clone company類
    public Object Clone() {
        Object clone = null;
        try {
            clone = super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return clone;
    }
}

//實現Cloneable接口的People類
public class People implements Cloneable {
    private String name;
    private Long age;
    private String gender;
    private Company company;

    public String getName() {
        return name;
    }

    public void setName(String name) {

        this.name = name;
    }

    public People() {
        //在給People賦name的同時建立company實例
        this.company = new Company();
    }

    public People(Company company) {
        this.company = (Company) company.Clone();
    }

    public Long getAge() {
        return age;
    }

    public void setAge(Long age) {
        this.age = age;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public Company getCompany() {
        return company;
    }

    public void setCompany(String level, Long workYears) {
        //給company的屬性賦值
        this.company.setLevel(level);
        this.company.setWorkYears(workYears);
    }

    //Clone()方法，clone people類
    public Object Clone() {
        Object object = null;
        try {
            object = super.clone();
　　　　　　　　//把引用類型company再拷貝一遍
            ((People)object).company = (Company) this.company.Clone();
        } catch (CloneNotSupportedException exception) {
            throw new RuntimeException(exception);
        }
        return  object;
    }

    public void show() {
        System.out.println("name:" + name + ",age:" + age + ",gender" + gender);
        System.out.println("name:" + name + ",level:" + company.getLevel() + ",workYears:" + company.getWorkYears());
    }
}