InversifyJS

InversifyJS 一个强大而轻量级的反转控件 (IoC) 容器，适用于由TypeScript编写的JavaScript和Node.js应用。它使用类构造函数去定义和注入它的依赖。InversifyJS API友好易懂，鼓励对OOP和IoC最佳实践的应用。

InversifyJS有4个主要目标:

1. 允许JavaScript开发人员编写遵循 SOLID 原则的代码。

2. 促进并鼓励遵守最佳的面向对象编程和依赖注入实践。

3. 尽可能少的运行时开销。

4. 提供艺术编程体验和生态。

使用

步骤 1：定义接口

// file interfaces.ts

export interface Warrior {
    fight(): string;
    sneak(): string;
}

export interface Weapon {
    hit(): string;
}

export interface ThrowableWeapon {
    throw(): string;
}

步骤 2：定义依赖

// file entities.ts

import { injectable, inject } from "inversify";
import "reflect-metadata";
import { Weapon, ThrowableWeapon, Warrior } from "./interfaces";
import { TYPES } from "./types";

@injectable()
class Katana implements Weapon {
    public hit() {
        return "cut!";
    }
}

@injectable()
class Shuriken implements ThrowableWeapon {
    public throw() {
        return "hit!";
    }
}

@injectable()
class Ninja implements Warrior {

    private _katana: Weapon;
    private _shuriken: ThrowableWeapon;

    public constructor(
	    @inject(TYPES.Weapon) katana: Weapon,
	    @inject(TYPES.ThrowableWeapon) shuriken: ThrowableWeapon
    ) {
        this._katana = katana;
        this._shuriken = shuriken;
    }

    public fight() { return this._katana.hit(); }
    public sneak() { return this._shuriken.throw(); }

}

export { Ninja, Katana, Shuriken };

步骤 3：创建并配置 IOC 容器

// file inversify.config.ts

import { Container } from "inversify";
import { TYPES } from "./types";
import { Warrior, Weapon, ThrowableWeapon } from "./interfaces";
import { Ninja, Katana, Shuriken } from "./entities";

const myContainer = new Container();
myContainer.bind<Warrior>(TYPES.Warrior).to(Ninja);
myContainer.bind<Weapon>(TYPES.Weapon).to(Katana);
myContainer.bind<ThrowableWeapon>(TYPES.ThrowableWeapon).to(Shuriken);

export { myContainer };

步骤4：依赖解析

import { myContainer } from "./inversify.config";
import { TYPES } from "./types";
import { Warrior } from "./interfaces";

const ninja = myContainer.get<Warrior>(TYPES.Warrior);

expect(ninja.fight()).eql("cut!"); // true
expect(ninja.sneak()).eql("hit!"); // true