职责链模式(Chain of Responsibility Pattern)
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定义：为请求创建了一个接收者对象的链。 目的：避免请求发送者与接收者耦合在一起，让多个对象都有可能接收请求，将这些对象连接成一条链，并且沿着这条链传递请求，直到有对象处理它为止。 场景：红楼梦中的"击鼓传花"。 |
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// 采购请求 let PurchaseRequest = (amount, productName) => { this.amount = amount this.productName = productName } // 处理方 let Approver = (name, nextApprover) => { this.name = name this.nextApprover = nextApprover } Approver.prototype.processRequest = () => { throw new Error() } // ConcreteHandler let Manager = (name, nextApprover) => { Approver.call(this, name, nextApprover) } extend(Manager, Approver) Manager.prototype.processRequest = (request) => { if (request.Amount < 10000.0) { console.log('ok') } else if (NextApprover != null) { this.nextApprover.ProcessRequest(request) } } // ConcreteHandler,副总 let VicePresident = function (name, nextApprover) { Approver.call(this, name, nextApprover) } extend(VicePresident, Approver); VicePresident.prototype.processRequest = function (request) { if (request.Amount < 25000.0) { console.log('ok'); } else if (NextApprover != null) { this.nextApprover.ProcessRequest(request) } } // ConcreteHandler，总经理 let President = function (name, nextApprover) { Approver.call(this, name, nextApprover) } extend(President, Approver) President.prototype.processRequest = function (request) { if (request.Amount < 100000.0) { console.log('ok') } else if (NextApprover != null) { this.nextApprover.ProcessRequest(request) } } let requestTelphone = new PurchaseRequest(4000.0, "Telphone") let requestSoftware = new PurchaseRequest(10000.0, "Visual Studio") let requestComputers = new PurchaseRequest(40000.0, "Computers") let manager = new Manager("LearningHard") let Vp = new VicePresident("Tony") let Pre = new President("BossTom") // 设置责任链 manager.NextApprover = Vp Vp.NextApprover = Pre // 处理请求 manager.ProcessRequest(requestTelphone) manager.ProcessRequest(requestSoftware) manager.ProcessRequest(requestComputers) |