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MVP（Model-View-Presenter）是一种软件架构模式。

MVP模式组成

Model

• 职责：负责数据管理和业务逻辑
• 包含：数据存储、数据获取、业务规则、数据验证等
• 特点：独立于用户界面，可以被多个View复用

View

• 职责：负责用户界面的显示和用户交互
• 包含：UI组件、用户输入处理、界面渲染等
• 特点：被动的，不直接与Model交互，只与Presenter通信

Presenter

• 职责：作为Model和View之间的中介
• 包含：处理用户交互逻辑、格式化数据、控制View更新等
• 特点：包含表示层逻辑，协调Model和View的交互

MVP模式数据流向

代码

用MVP模式实现CounterApp
model层
model应该有让调用方订阅和通知订阅方的能力。

export interface IModel<ModelData, ModelEvent> {addEventListener<T extends keyof ModelEvent>(type: T, callback: ModelEvent[T]): DisposeHandler;subscribeModelData(callback: (data: ModelData) => void): DisposeHandler;getModelData(): ModelData;
}

CounterModel的类型定义

export type CounterModelEvent = {"data:update": (data: number) => void;
};export type CounterModelData = numberexport interface ICounterModel extends IModel<CounterModelData, CounterModelEvent> {count : number
}

定义ICounterModel，面相接口编程。
CounterModel的代码实现

export class CounterModel implements ICounterModel
{eventemitter = new EventEmitter<CounterModelEvent>();private _count: number = 0;getModelData() {return this.count;}protected notifyDataUpdate(): void {this.eventemitter.emit("data:update", this.getModelData());}addEventListener<T extends keyof CounterModelEvent>(type: T,callback: CounterModelEvent[T]): DisposeHandler {this.eventemitter.on(type, callback as any);return () => {this.eventemitter.off(type, callback);};}subscribeModelData(callback: (data: CounterModelData) => void): DisposeHandler {return this.addEventListener("data:update", callback);}get count() {return this._count;}set count(value: number) {this._count = value;this.notifyDataUpdate();}
}

view层
view应该有订阅业务事件和渲染视图的能力

export interface IView<ViewEvent extends Record<string, Function>, ViewRenderData extends Object> {addEventListener<T extends keyof ViewEvent>(type: T, callback: ViewEvent[T]): () => void;render(data: ViewRenderData): void;destroy(): void;}

ICounterView类型定义

export type CounterViewEvent = {"click:increment": () => void;"click:decrement": () => void;
};export type CounterViewRenderData = {count: number;
};export interface ICounterView extends IView<CounterViewEvent, CounterViewRenderData> {}

CounterView代码

class CounterView implements ICounterView {private disposeList: DisposeHandler[] = [];private container: HTMLElement;private counterContainer!: HTMLDivElement;private eventemitter = new EventEmitter<CounterViewEvent>();constructor(container: HTMLElement) {this.container = container;this.init();}// 初始化视图绑定视图事件init() {this.disposeList.push(this.createDecrementButton());this.createCounterContainer()this.disposeList.push(this.createIncrementButton());}private createIncrementButton() {const incrementButton = document.createElement("button");incrementButton.textContent = "Increment";const handler = () => {this.eventemitter.emit("click:increment");};incrementButton.addEventListener("click",handler );return () => {incrementButton.removeEventListener("click", handler);};}private createCounterContainer() {const counterContainer = document.createElement("div");counterContainer.textContent = "0";this.container.appendChild(counterContainer);}private createDecrementButton() {const decrementButton = document.createElement("button");decrementButton.textContent = "Decrement";const handler = () => {this.eventemitter.emit("click:decrement");};decrementButton.addEventListener("click", handler);return () => {decrementButton.removeEventListener("click", handler);};}addEventListener<T extends keyof CounterViewEvent>(type: T,callback: CounterViewEvent[T]): () => void {this.eventemitter.on(type, callback);return () => {this.eventemitter.off(type, callback);};}render(data: { count: number }) {this.counterContainer.textContent = data.count.toString();}destroy(): void {this.disposeList.forEach((dispose) => dispose());this.container.innerHTML = "";}
}

Presenter
CounterPresenter负责协调counterModel和counterView。

export class CounterPresenter implements IPresenter {private counterModel: ICounterModel;private counterView: ICounterView;constructor(counterModel: CounterModel, counterView: ICounterView) {this.counterModel = counterModel;this.counterView = counterView;}init() {this.bindViewEvent();this.bindModelEvent();}bindViewEvent() {this.counterView.addEventListener("click:increment", () => {this.counterModel.count += 1;});this.counterView.addEventListener("click:decrement", () => {this.counterModel.count -= 1;});}bindModelEvent() {this.counterModel.addEventListener("data:update", (data) => {this.counterView.render({ count: data });});}destroy(): void {this.counterModel = null;this.counterView = null;}
}

CounterApp负责初始化Model,View和Presenter，管理应用的生命周期，对外提供接口。

export class CounterApp {private counterModel!: CounterModel;private container: HTMLElement;private counterView!: CounterView;private counterPresenter!: CounterPresenter;constructor(container: HTMLElement) {this.container = container;this.createModels();this.createViews();this.createPresenters();this.initPresenters();}private createModels() {this.counterModel = new CounterModel(sameDetector);}private createViews() {this.counterView = new CounterView(this.container);}private createPresenters() {this.counterPresenter = new CounterPresenter(this.counterModel, this.counterView);}private initPresenters() {this.counterPresenter.init();}destroy() {this.counterPresenter.destroy();this.counterView.destroy();this.counterModel = null;}
}

用react的同学都知道，react有批处理机制，这里对model也做一个简单优化，避免一段逻辑触发多次model数据更新通知。
model接口修改添加两个方法

export interface IModel<ModelData, ModelEvent> {// ......startBatchUpdate(): void; // 开始批量更新finishBatchUpdate(): void; // 结束批量更新
}

数据层批处理的代码是类似的，行为可以让子类重写
BaseModel定义批处理流程

export abstract class BaseModel<ModelData, ModelEvent> implements IModel<ModelData, ModelEvent> {protected _isStartBatchUpdate: boolean = false; // 是否开始批量更新private beforeStartBatchUpdateModelData: ModelData | null = null; // 批量更新前的模型数据startBatchUpdate() {this._isStartBatchUpdate = true; // 开始批量更新this.beforeStartBatchUpdateModelData = this.getModelData(); // 记录批量更新前的模型数据}abstract getModelData(): ModelData;abstract isSame(oldData: ModelData, newData: ModelData): boolean;abstract addEventListener<T extends keyof ModelEvent>(type: T, callback: ModelEvent[T]): () => void;abstract subscribeModelData(callback: (data: ModelData) => void): () => void;finishBatchUpdate() {this._isStartBatchUpdate = false; // 结束批量更新if (this.beforeStartBatchUpdateModelData) {// 如果有批量更新前的模型数据，则比较是否有变化if (this.isSame(this.beforeStartBatchUpdateModelData, this.getModelData())) {return; // 如果没有变化，则不通知数据更新}this.beforeStartBatchUpdateModelData = null; // 清空批量更新前的模型数据}this.notifyDataUpdate(); // 通知数据更新}protected abstract notifyDataUpdate(): void; // 通知数据更新
}

这个例子view，model，presenter复杂度低，没有涉及多个view，model和presenter的情况，虽然比较简单，能通过这个应用理解MVP模式。

模式特点model层和view层解耦，presenter负责协调view层和model层。
优点

• 依赖接口可以方便进行mock测试
• model层独立于view层，可以被多个view层使用
• 数据流向清晰

缺点

• 简单应用容易复杂化
• 事件驱动容易提高调试复杂度，观察者模式也容易提高调试复杂度
• Presenter层承担太多职责容易导致臃肿
• 团队开发成本比较高