备忘录模式--行为模式

适用场景

需要记录的源类

package design.behavior.memento;

public class Stats {
    private String name;
    private String age;
    private String money;

    public Stats(String name, String age, String money) {
        this.name = name;
        this.age = age;
        this.money = money;
    }

    /**
     * 数据备份
     * @return
     */
    public Memento memento(){
        return new Memento(this);
    }

    /**
     * 恢复
     * @param memento
     * @return
     */
    public Stats recovery(Memento memento){
        return new Stats(memento.getName(),memento.getAge(),memento.getMoney());
    }

    public String getName() {
        return name;
    }

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

    public String getAge() {
        return age;
    }

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

    public String getMoney() {
        return money;
    }

    public void setMoney(String money) {
        this.money = money;
    }
}

备忘录(又叫便利贴纸)

package design.behavior.memento;

public class Memento {

    private String name;
    private String age;
    private String money;

    Memento(Stats stats){
        this.name=stats.getName();
        this.age=stats.getAge();
        this.money=stats.getMoney();
    }



    public String getName() {
        return name;
    }

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

    public String getAge() {
        return age;
    }

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

    public String getMoney() {
        return money;
    }

    public void setMoney(String money) {
        this.money = money;
    }
}

CareTask存放备忘录的地方

package design.behavior.memento;

import java.util.LinkedList;

public class CareTask {
    private LinkedList<Memento> linkedList = new LinkedList();

    public Memento getMemento(){
        if(linkedList.size()>0){
            return linkedList.pop();
        }
      return null;
    }

    public void setMemento(Memento memento){
        linkedList.push(memento);
    }

}

客户端client

package design.behavior.memento;

/**
 * 备忘录模式-记录每次操作的状态,用于回滚
 */
public class Client {
    public static void main(String[] args) {
        CareTask careTask = new CareTask();
        Stats yyj = new Stats("yyj", "10", "2000");
        careTask.setMemento(yyj.memento());
        showStats(yyj);

        yyj.setMoney("11000");
        yyj.setAge("28");
        careTask.setMemento(yyj.memento());
        showStats(yyj);

        yyj.setMoney("21000");
        yyj.setAge("38");
        showStats(yyj);

        yyj = yyj.recovery(careTask.getMemento());
        showStats(yyj);

        yyj = yyj.recovery(careTask.getMemento());
        showStats(yyj);

    }
    private static void  showStats(Stats stats){
        System.out.println(String.format("我的名字:%s,我的年龄%s,我的工资%s"
                ,stats.getName(),stats.getAge(),stats.getMoney()));
    }
}

其实备忘录模式某种意义上就是把对象clone一次,放在linkedList中,每次操作都Push进去,回滚就把状态对象pop出来