设计模式——状态模式

状态模式（状态对象模式）：将状态和行为绑定起来，允许一个对象内部状态改变的时候，改变其行为！

本质上是将行为封装在状态中。

角色：1、状态行为的抽象 2、实际状态对象 3、状态环境（将状态作为成员变量）

下面看实际代码：

状态行为抽象

/*
 * Copyright (c) 2017. Xiaomi.Co.Ltd All rights reserved
 */

package com.pt.state;

/**
 * @description 贷款行为，实际上这个可以定义为抽象类
 * @author panteng
 * @date 17-2-27.
 */
public interface ILoan {
    Float getLoan(Float loanAmount);
}

ILoan

实际状态（状态对应行为的实现）

名字命名不太恰当，实际上这个类并不是person，而是person的状态！

/*
 * Copyright (c) 2017. Xiaomi.Co.Ltd All rights reserved
 */

package com.pt.state;

/**
 * @description
 * @author panteng
 * @date 17-2-27.
 */
public class GeneralPerson implements ILoan {
    String stat = "普通人员";

    public Float getLoan(Float loanAmount){
        System.out.println("排队... ...");
        if (loanAmount > 10000) {
            System.out.println("贷款金额太大，不予审批");
        } else {
            System.out.println("审批中... ...");
            System.out.println("放款... ...");
            return loanAmount;
        }
        return 0F;
    }
}

GeneralPerson

/*
 * Copyright (c) 2017. Xiaomi.Co.Ltd All rights reserved
 */

package com.pt.state;

/**
 * @description
 * @author panteng
 * @date 17-2-27.
 */
public class VIPPerson implements ILoan {
    String stat = "VIP 人员";

    public Float getLoan(Float loanAmount){
        System.out.println("走VIP通道... ...");
        if (loanAmount > 100000) {
            System.out.println("审批中... ...");
            if (loanAmount > 500000) {
                System.out.println("贷款金额太大，不予审批");
            } else {
                System.out.println("审批通过");
                System.out.println("放款... ...");
            }
        } else {
            System.out.println("放款... ...");
            return loanAmount;
        }
        return 0F;
    }
}

VIPPerson

状态环境

/*
 * Copyright (c) 2017. Xiaomi.Co.Ltd All rights reserved
 */

package com.pt.state;

/**
 * @description 相当于状态的环境
 * @author panteng
 * @date 17-2-27.
 */
public class Person {
    String name;
    String id;
    String phoneNum;
    ILoan state;        //用户状态

    public Person(){
    }

    public Person(String name, String id, String phoneNum, ILoan state){
        this.name = name;
        this.id = id;
        this.phoneNum = phoneNum;
        this.state = state;
    }

    public String getName(){
        return name;
    }
    public void setName(String name){
        this.name = name;
    }
    public String getId(){
        return id;
    }
    public void setId(String id){
        this.id = id;
    }
    public String getPhoneNum(){
        return phoneNum;
    }
    public void setPhoneNum(String phoneNum){
        this.phoneNum = phoneNum;
    }
    public ILoan getState(){
        return state;
    }
    public void setState(ILoan state){
        this.state = state;
    }

    public void loanAction(Float amount){
        this.state.getLoan(amount);
    }
}

Person

测试

/*
 * Copyright (c) 2017. Xiaomi.Co.Ltd All rights reserved
 */

package com.pt.state;

import org.junit.Test;

/**
 * @description
 * @author panteng
 * @date 17-2-27.
 */
public class StateTest {
    @Test
    public void stateTest(){
        ILoan state1 = new GeneralPerson();
        Person person = new Person("pt", "10001010112", "13840410382", state1);

        //普通状态
        person.loanAction(1000F);
        System.out.println("=========================================");
        person.loanAction(100001F);

        //切换到VIP状态
        ILoan state2 = new VIPPerson();
        person.setState(state2);
        System.out.println("=========================================");
        person.loanAction(1000F);
        System.out.println("=========================================");
        person.loanAction(100001F);

    }
}