贯穿设计模式-责任链模式

样例代码

涉及到的项目样例代码均可以从https://github.com/WeiXiao-Hyy/Design-Patterns.git获取

需求

实时地，根据city，sex，product字段进行业务投放，比如：北京的男生；四川的电脑等等 → 责任链模式（责任链表模式）

UML图

责任链模式

handler自身含有next指针和链表类似，使用Apollo进行动态配置字段进行规则变更

Apollo访问不到内网地址

由于Apollo使用Docker进行安装，导致Apollo访问不到configserver的地址

app:id: DesignPatternLearning# apollo
apollo:meta: "http://localhost:8080"bootstrap:enabled: trueeagerLoad:enabled: truecacheDir:"/Users/hujiale/GitCode/Apoll"logger:level:com:info

执行时在JVM参数添加-Dapollo.configService=http://localhost:8080即可解决

核心代码

在这里插入图片描述

//组装责任链条并返回责任链条首节点
private AbstractBusinessHandler buildChain() {//如果没有配置,直接返回nullif (Objects.isNull(this.handlerType)) {return null;}if (Objects.isNull(this.currentHandlerType)) {this.currentHandlerType = this.handlerType;}if (this.currentHandlerType.equals(this.handlerType) && Objects.nonNull(this.currentHandler)) {return this.currentHandler;} else {log.info("config modified or first init, start to assemble duty chain.");synchronized (this) {try {//伪头节点AbstractBusinessHandler dummyHeadHandler = new CityHandler();AbstractBusinessHandler preHandler = dummyHeadHandler;//采用反射实例化责任链节点String[] handlerTypeList = this.handlerType.split(",");for (String handlerType : handlerTypeList) {AbstractBusinessHandler handler = (AbstractBusinessHandler)Class.forName(HandlerEnum.valueOf(handlerType).getValue()).newInstance();preHandler.nextHandler = handler;preHandler = handler;}// 初始化类中变量this.currentHandler = dummyHeadHandler.nextHandler;this.currentHandlerType = this.handlerType;return this.currentHandler;} catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {throw new UnsupportedOperationException(e);}}}
}