設計模式之原型設計模式

原型設計模式

原型設計模式的定義是原型實例指定對象的類型，通過拷貝這些原型來創建新的對象

原型設計的例子

以<<大話設計模式>>例子為例子:我們求職投簡歷，經歷這一欄在投不同的公司需要修改，我們不要再去創建個人信息、工作經歷，
通過拷貝來減少簡歷中對象的創建。

簡歷父類

package com.learn.java.javabase.designpattern.prototype;

import lombok.Data;

@Data
public class Resume implements Cloneable {
    private String id;

    @Override
    public Resume clone() throws CloneNotSupportedException {
        Resume resume = null;
        resume = (Resume) super.clone();
        return resume;
    }
}

簡歷的實現類

package com.learn.java.javabase.designpattern.prototype;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;

@Data
@AllArgsConstructor
@Slf4j
public class CloneResume01 extends Resume {
    private String name;
    private String age;
    private String year;
    private String workInfo;
    private Remark remark;

    //    public CloneResume01(Remark remark)
//    {
//        this.remark =remark.clone();
//    }
    public CloneResume01(String age, String name) {
        this.age = age;
        this.name = name;
    }

    public CloneResume01(String age, String name, Remark remark) {
        this.age = age;
        this.name = name;
        this.remark = remark;
    }

    public void setWorkInfo(String year, String workinfo) {
        this.year = year;
        this.workInfo = workinfo;
    }

    public void display() {
        log.info("name = {} ,age = {} , in year {}  {},remark ={}", name, age, year, workInfo, remark.toString());
    }

    @Override
    public CloneResume01 clone() {
        CloneResume01 cloneResume01 =null;
        try {
            cloneResume01 = (CloneResume01) super.clone();
            cloneResume01.setRemark(this.getRemark().clone());
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return cloneResume01;
    }
}

簡歷中的備注類Remark

備注類作為簡歷的一個屬性，因為淺復制只能復制String等基礎數據類型的值，但對於其他的引用類型並沒有拷貝值，只傳遞對象的引用地址
因此重寫Remark類的clone方法，進行深度復制，並在簡歷類中調用clone方法完成深度復制。

package com.learn.java.javabase.designpattern.prototype;

import lombok.AllArgsConstructor;
import lombok.Data;

@Data
@AllArgsConstructor
public class Remark implements Cloneable {
    private String remarkValue;

    @Override
    public Remark clone() {
        Remark remark = null;
        try {
            remark = (Remark) super.clone();
        } catch (CloneNotSupportedException e) {
            e.printStackTrace();
        }
        return remark;
    }
    @Override
    public String toString(){
        return remarkValue;
    }

}

測試類

package com.learn.java.javabase.designpattern.prototype;

public class TestProtoType {
    public static void main(String[] args) {
        CloneResume01 jackResume=new CloneResume01("fang","28","2017-2019","comp1"
                ,new Remark("first job"));
        CloneResume01 jackResume02=jackResume.clone();
        //Remark沒有實現clone方法，下面這句話會因為是復制新的Remark對象,所以打印的Remark是不一樣的
        //jackResume02.setRemark(new Remark("second job"));
        //淺復制和深復制,Remark和Resume實現類兩個clone方法沒有修改,會因為淺復制嗎,導致拷貝的實例的值與原型的值是一樣的
        jackResume02.getRemark().setRemarkValue("second job");
        jackResume02.setWorkInfo("2020-now","comp2");
        jackResume.display();
        jackResume02.display();
    }
}

運行結果

22:44:53.007 [main] INFO com.learn.java.javabase.designpattern.prototype.CloneResume01 - name = fang ,age = 28 , in year 2017-2019  comp1,remark =first job
22:44:53.010 [main] INFO com.learn.java.javabase.designpattern.prototype.CloneResume01 - name = fang ,age = 28 , in year 2020-now  comp2,remark =second job