設(shè)計(jì)模式之職責(zé)鏈模式

在業(yè)務(wù)開(kāi)發(fā)中孙援，為了處理某個(gè)屬性害淤，可能需要復(fù)雜的處理邏輯，才能得到拓售，一般的做法是按步驟處理窥摄，最終得到想要的結(jié)果。作者的業(yè)務(wù)場(chǎng)景為計(jì)算用戶的年化收益率础淤，這個(gè)年化收益率是根據(jù)用戶的行為計(jì)算而來(lái)崭放。目前項(xiàng)目中的代碼是按常規(guī)步驟處理，代碼非掣胄祝混亂币砂，今天重新看一下代碼，覺(jué)得可以使用職責(zé)鏈模式來(lái)解決吱瘩。

業(yè)務(wù)場(chǎng)景：

產(chǎn)品為一款WIFI連接APP道伟，類(lèi)似萬(wàn)能鑰匙之類(lèi)的，并有理財(cái)功能使碾，理財(cái)?shù)哪昊找媛适歉鶕?jù)用戶的行為計(jì)算而來(lái)蜜徽，用戶打開(kāi)理財(cái)頁(yè)面的時(shí)候，根據(jù)用戶前一天的行為計(jì)算年化收益率

用戶行為：

這里只列出以下幾種票摇，實(shí)際情況更加復(fù)雜拘鞋，種類(lèi)跟多

1.是否為vip
2.是否分享過(guò)wifi
3.是否使用過(guò)連接wifi
4.通過(guò)連接wifi使用的流量，流量使用越多矢门，加息越多
5.是否支付1元盆色，購(gòu)買(mǎi)加息

當(dāng)前的處理邏輯

double totalYield = 0.04;//某基金基礎(chǔ)年化收益率
int vipCode = getUserVipCode();
if(vipCode.equlas("100")){
  totalYield = totalYiedl+0.02;//如果是vip，就增加0.02
}
boolean wifiConnect = getWifiConnect();
if(wifiConnect){
  totalYield = totalYiedl+0.01;//如果連接過(guò)wifi祟剔，就增加0.01
}
//如果分享過(guò)wifi隔躲，就增加0.01
//如果...，就增加...
...
return totalYield;

這里只是偽代碼物延，實(shí)際項(xiàng)目中有好幾百行宣旱，如果算上調(diào)用其他service層的代碼，估計(jì)有上千行代碼叛薯，
接下來(lái)浑吟，作者使用職責(zé)鏈模式來(lái)重構(gòu)一下這個(gè)業(yè)務(wù)邏輯代碼笙纤。

類(lèi)圖

年化收益率類(lèi)圖.JPG

UserActive 用戶行為
YeildCaculatorHandler 抽象類(lèi)年化收益率計(jì)算器
YeildCaculatorOfVip vip年化收益率計(jì)算器
YeildCaculatorOfFlow 流量使用年化收益率計(jì)算器
YeildCaculatorOfOneYuan 購(gòu)買(mǎi)一元加息年化收益率計(jì)算器
YeildCaculatorOfShare 分享WIFI年化收益率計(jì)算器
YeildCaculatorOfWifiConnect WIFI連接年化收益率計(jì)算器

UserActivie

package com.charlie.wifi.yeild;

public class UserActive {

    private String userName;
    private int vipCode;
    private boolean oneYuan;
    private boolean wifiConnect;
    private int flow;
    private boolean share;
    private double totalYeild = 0.04;

    public UserActive(String userName, int vipCode, boolean oneYuan, boolean wifiConnect, int flow, boolean share) {
        super();
        this.userName = userName;
        this.vipCode = vipCode;
        this.oneYuan = oneYuan;
        this.wifiConnect = wifiConnect;
        this.flow = flow;
        this.share = share;
    }
//省略get set

YeildCaculatorHandler

package com.charlie.wifi.yeild;

public abstract class YeildCaculatorHandler {

    protected String name;

    protected YeildCaculatorHandler successor;

    public YeildCaculatorHandler(String name) {
        super();
        this.name = name;
    }

    public void setSuccessor(YeildCaculatorHandler successor) {
        this.successor = successor;
    }

    public abstract double caculator(UserActive userActive);

}

YeildCaculatorOfFlow

package com.charlie.wifi.yeild;

import java.math.BigDecimal;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class YeildCaculatorOfFlow extends YeildCaculatorHandler {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    public YeildCaculatorOfFlow(String name) {
        super(name);
    }

    @Override
    public double caculator(UserActive userActive) {
        if (userActive.getFlow() > 0) {
            BigDecimal totalYeild = new BigDecimal(String.valueOf(userActive.getTotalYeild()));
            BigDecimal flowYeild = new BigDecimal(String.valueOf(userActive.getFlow() * 0.0001));
            userActive.setTotalYeild(totalYeild.add(flowYeild).doubleValue());
            logger.info("【" + userActive.getUserName() + "】" + "使用了流量" + userActive.getFlow() + "M，年華收益率為"
                    + userActive.getTotalYeild());
        } else {
            logger.info("【" + userActive.getUserName() + "】" + "沒(méi)有使用流量组力，年華收益率為" + userActive.getTotalYeild());
        }
        if (successor != null) {
            successor.caculator(userActive);
        }
        return userActive.getTotalYeild();
    }

}

YeildCaculatorOfOneYuan

package com.charlie.wifi.yeild;

import java.math.BigDecimal;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class YeildCaculatorOfOneYuan extends YeildCaculatorHandler {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    public YeildCaculatorOfOneYuan(String name) {
        super(name);
    }

    @Override
    public double caculator(UserActive userActive) {
        if (userActive.isOneYuan()) {
            BigDecimal totalYeild = new BigDecimal(String.valueOf(userActive.getTotalYeild()));
            BigDecimal oneYuanYeild = new BigDecimal("0.01");
            userActive.setTotalYeild(totalYeild.add(oneYuanYeild).doubleValue());
            logger.info("【" + userActive.getUserName() + "】" + "參與了1元加息省容，年華收益率為" + userActive.getTotalYeild());
        } else {
            logger.info("【" + userActive.getUserName() + "】" + "沒(méi)有參與了1元加息，年華收益率為" + userActive.getTotalYeild());
        }
        if (successor != null) {
            successor.caculator(userActive);
        }

        return userActive.getTotalYeild();
    }

}

YeildCaculatorOfShare

package com.charlie.wifi.yeild;

import java.math.BigDecimal;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class YeildCaculatorOfShare extends YeildCaculatorHandler {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    public YeildCaculatorOfShare(String name) {
        super(name);
    }

    @Override
    public double caculator(UserActive userActive) {
        if (userActive.isShare()) {
            BigDecimal totalYeild = new BigDecimal(String.valueOf(userActive.getTotalYeild()));
            BigDecimal shareYeild = new BigDecimal("0.01");
            userActive.setTotalYeild(totalYeild.add(shareYeild).doubleValue());
            logger.info("【" + userActive.getUserName() + "】" + "分享了WIFI燎字，年華收益率為" + userActive.getTotalYeild());
        } else {
            logger.info("【" + userActive.getUserName() + "】" + "沒(méi)有分享WIFI腥椒，年華收益率為" + userActive.getTotalYeild());
        }
        if (successor != null) {
            successor.caculator(userActive);
        }
        return userActive.getTotalYeild();
    }

}

YeildCaculatorOfVip

package com.charlie.wifi.yeild;

import java.math.BigDecimal;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class YeildCaculatorOfVip extends YeildCaculatorHandler {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    public YeildCaculatorOfVip(String name) {
        super(name);
    }

    @Override
    public double caculator(UserActive userActive) {
        if (userActive.getVipCode() == 100) {
            BigDecimal totalYeild = new BigDecimal(String.valueOf(userActive.getTotalYeild()));
            BigDecimal vipYeild = new BigDecimal("0.02");
            userActive.setTotalYeild(totalYeild.add(vipYeild).doubleValue());
            logger.info("【" + userActive.getUserName() + "】" + "為VIP，年華收益率為" + userActive.getTotalYeild());
        } else {
            logger.info("【" + userActive.getUserName() + "】" + "為非VIP轩触，年華收益率為" + userActive.getTotalYeild());
        }
        if (successor != null) {
            successor.caculator(userActive);
        }
        return userActive.getTotalYeild();
    }

}

YeildCaculatorOfWifiConnect

package com.charlie.wifi.yeild;

import java.math.BigDecimal;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class YeildCaculatorOfWifiConnect extends YeildCaculatorHandler {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    public YeildCaculatorOfWifiConnect(String name) {
        super(name);
    }

    @Override
    public double caculator(UserActive userActive) {
        if (userActive.isWifiConnect()) {
            BigDecimal totalYeild = new BigDecimal(String.valueOf(userActive.getTotalYeild()));
            BigDecimal vipYeild = new BigDecimal("0.01");
            userActive.setTotalYeild(totalYeild.add(vipYeild).doubleValue());
            logger.info("【" + userActive.getUserName() + "】" + "連接了WIFI寞酿，年華收益率為" + userActive.getTotalYeild());
        } else {
            logger.info("【" + userActive.getUserName() + "】" + "沒(méi)有連接WIFI家夺，年華收益率為" + userActive.getTotalYeild());
        }
        if (successor != null) {
            successor.caculator(userActive);
        }
        return userActive.getTotalYeild();
    }

}

Main

package com.charlie.wifi.yeild;

import java.math.BigDecimal;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class Main {

    private static final Logger logger = LoggerFactory.getLogger(Main.class);

    public static void main(String[] args) {
        UserActive xiaoming = new UserActive("小明", 0, false, false, 0, false);
        UserActive xiaowang = new UserActive("小王", 100, false, true, 0, false);
        UserActive xiaoli = new UserActive("小李", 0, true, false, 0, true);
        UserActive xiaojiang = new UserActive("小姜", 100, true, true, 100, true);

        YeildCaculatorHandler vip = new YeildCaculatorOfVip("VIP加息計(jì)算器");
        YeildCaculatorHandler oneYuan = new YeildCaculatorOfOneYuan("一元加息計(jì)算器");
        YeildCaculatorHandler wifiConnect = new YeildCaculatorOfWifiConnect("WIFI連接計(jì)算器");
        YeildCaculatorHandler share = new YeildCaculatorOfShare("分享WIFI計(jì)算器");
        YeildCaculatorHandler flow = new YeildCaculatorOfFlow("流量使用計(jì)算器");

        vip.setSuccessor(oneYuan);
        oneYuan.setSuccessor(wifiConnect);
        wifiConnect.setSuccessor(share);
        share.setSuccessor(flow);

        vip.caculator(xiaoming);
        logger.info("\n");
        vip.caculator(xiaowang);
        logger.info("\n");
        vip.caculator(xiaoli);
        logger.info("\n");
        vip.caculator(xiaojiang);

        logger.info("【小姜】最終年化收益率為" + xiaojiang.getTotalYeild());

    }

}

運(yùn)行結(jié)果

INFO  com.charlie.wifi.yeild.YeildCaculatorOfVip - 【小明】為非VIP脱柱，年華收益率為0.04
INFO  com.charlie.wifi.yeild.YeildCaculatorOfOneYuan - 【小明】沒(méi)有參與了1元加息，年華收益率為0.04
INFO  com.charlie.wifi.yeild.YeildCaculatorOfWifiConnect - 【小明】沒(méi)有連接WIFI拉馋，年華收益率為0.04
INFO  com.charlie.wifi.yeild.YeildCaculatorOfShare - 【小明】沒(méi)有分享WIFI榨为，年華收益率為0.04
INFO  com.charlie.wifi.yeild.YeildCaculatorOfFlow - 【小明】沒(méi)有使用流量，年華收益率為0.04
INFO  com.charlie.wifi.yeild.Main - 【小明】最終年化收益率為0.04

INFO  com.charlie.wifi.yeild.YeildCaculatorOfVip - 【小王】為VIP煌茴，年華收益率為0.06
INFO  com.charlie.wifi.yeild.YeildCaculatorOfOneYuan - 【小王】沒(méi)有參與了1元加息随闺，年華收益率為0.06
INFO  com.charlie.wifi.yeild.YeildCaculatorOfWifiConnect - 【小王】連接了WIFI，年華收益率為0.07
INFO  com.charlie.wifi.yeild.YeildCaculatorOfShare - 【小王】沒(méi)有分享WIFI蔓腐，年華收益率為0.07
INFO  com.charlie.wifi.yeild.YeildCaculatorOfFlow - 【小王】沒(méi)有使用流量矩乐，年華收益率為0.07
INFO  com.charlie.wifi.yeild.Main - 【小王】最終年化收益率為0.07

INFO  com.charlie.wifi.yeild.YeildCaculatorOfVip - 【小李】為非VIP，年華收益率為0.04
INFO  com.charlie.wifi.yeild.YeildCaculatorOfOneYuan - 【小李】參與了1元加息回论，年華收益率為0.05
INFO  com.charlie.wifi.yeild.YeildCaculatorOfWifiConnect - 【小李】沒(méi)有連接WIFI散罕，年華收益率為0.05
INFO  com.charlie.wifi.yeild.YeildCaculatorOfShare - 【小李】分享了WIFI，年華收益率為0.06
INFO  com.charlie.wifi.yeild.YeildCaculatorOfFlow - 【小李】沒(méi)有使用流量傀蓉，年華收益率為0.06
INFO  com.charlie.wifi.yeild.Main - 【小李】最終年化收益率為0.06

INFO  com.charlie.wifi.yeild.YeildCaculatorOfVip - 【小姜】為VIP欧漱，年華收益率為0.06
INFO  com.charlie.wifi.yeild.YeildCaculatorOfOneYuan - 【小姜】參與了1元加息，年華收益率為0.07
INFO  com.charlie.wifi.yeild.YeildCaculatorOfWifiConnect - 【小姜】連接了WIFI葬燎，年華收益率為0.08
INFO  com.charlie.wifi.yeild.YeildCaculatorOfShare - 【小姜】分享了WIFI误甚，年華收益率為0.09
INFO  com.charlie.wifi.yeild.YeildCaculatorOfFlow - 【小姜】使用了流量100M，年華收益率為0.1
INFO  com.charlie.wifi.yeild.Main - 【小姜】最終年化收益率為0.1

總結(jié)

通過(guò)重構(gòu)谱净，將用戶行為的查詢(xún)窑邦，不同行為的加息計(jì)算處理分別解耦，之前是全部耦合在一起壕探。這樣維護(hù)起來(lái)非常方便冈钦，比如流量使用年化收益率的業(yè)務(wù)規(guī)則改變了，那么我就修改這個(gè)計(jì)算器就行浩蓉，如果增加新的用戶加息行為派继，就再增加一個(gè)計(jì)算器宾袜，如果取消了某個(gè)用戶加息行為，就去掉就行驾窟，如果在之前幾百行的代碼里面去修改庆猫，就會(huì)顯得非常的頭疼。其實(shí)很多時(shí)候绅络，當(dāng)業(yè)務(wù)規(guī)則簡(jiǎn)單的時(shí)候月培，不使用設(shè)計(jì)模式，也沒(méi)有什么問(wèn)題恩急，維護(hù)起來(lái)也不難杉畜。只有當(dāng)業(yè)務(wù)規(guī)則非常之多，越來(lái)越復(fù)雜的時(shí)候衷恭，問(wèn)題就會(huì)暴露出來(lái)此叠。就像訪問(wèn)量一樣，一個(gè)接口的訪問(wèn)量是100w和100随珠，接口的處理是完全不一樣的灭袁。

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