实现观察者模式示例，添加观察者、目标及具体实现，增强代码可读性

2026-01-06 23:44:08 +08:00
parent 5022b481a4
commit 5ddda4ee95
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+/*
+实例：
+汤宝宝一时想不开，当了房产中介。
+一旦片区内有房东发布了新房源信息，他就会第一时间通知所有潜在租客。
+*/
+
+// 观察者抽象接口
+interface Observer {
+  update(): void;
+}
+
+// 目标抽象接口
+interface Subject {
+  attach(observer: Observer): void;
+  detach(observer: Observer): void;
+  notify(): void;
+}
+
+// 具体目标类
+class HousingAgency implements Subject {
+  private observers: Observer[];
+
+  constructor() {
+    this.observers = [];
+  }
+
+  attach(observer: Observer): void {
+    const isExist = this.observers.includes(observer);
+    if (isExist) {
+      return console.log("Observer has been attached already.");
+    }
+    this.observers.push(observer);
+  }
+
+  detach(observer: Observer): void {
+    const observerIndex = this.observers.indexOf(observer);
+    if (observerIndex === -1) {
+      return console.log("Nonexistent observer.");
+    }
+    this.observers.splice(observerIndex, 1);
+  }
+
+  notify(): void {
+    console.log("房产中介通知了所有租客。");
+    for (const observer of this.observers) {
+      observer.update();
+    }
+  }
+}
+
+// 具体观察者类
+class TenantObs implements Observer {
+  private name: string;
+
+  constructor(name: string) {
+    this.name = name;
+  }
+
+  update(): void {
+    console.log(`租客${this.name}收到了房源更新通知。`);
+  }
+}
+
+(function () {
+  console.log("============= 观察者模式 =============");
+  const agency = new HousingAgency();
+  const tenant1 = new TenantObs("小明");
+  const tenant2 = new TenantObs("小红");
+  console.log("小红和小明订阅了房产中介的房源信息。");
+  agency.attach(tenant1);
+  agency.attach(tenant2);
+  console.log("房源上新了！");
+  agency.notify();
+
+  console.log("-----");
+  console.log("小红不想再接收房源信息，退订了。");
+  agency.detach(tenant2);
+  console.log("又有新房源了！");
+  agency.notify();
+
+  console.log("\n=========== 观察者模式结束 ===========");
+})();