typescript: Singleton Pattern

发布时间 2023-10-06 15:02:36作者: ®Geovin Du Dream Park™

 

/**
 * file: Singletonts.ts
 *  Singleton Pattern 单例是一种创建型设计模式, 让你能够保证一个类只有一个实例, 并提供一个访问该实例的全局节点。
 * The Singleton class defines the `getInstance` method that lets clients access
 * the unique singleton instance.
 */
class Singleton {
    private static instance: Singleton;

    /**
     * The Singleton's constructor should always be private to prevent direct
     * construction calls with the `new` operator.
     */
    private constructor() { }

    /**
     * The static method that controls the access to the singleton instance.
     *
     * This implementation let you subclass the Singleton class while keeping
     * just one instance of each subclass around.
     */
    public static getInstance(): Singleton {
        if (!Singleton.instance) {
            Singleton.instance = new Singleton();
        }

        return Singleton.instance;
    }

    /**
     * Finally, any singleton should define some business logic, which can be
     * executed on its instance.
     */
    public someBusinessLogic() {
        // ...
    }
}

/**
 * The client code.
 */
function clientCodeDu() {
    const s1 = Singleton.getInstance();
    const s2 = Singleton.getInstance();
    let stdu="";
    if (s1 == s2) {
        console.log('Singleton works, both variables contain the same instance.');
        stdu="Singleton works";
    } else {
        console.log('Singleton failed, variables contain different instances.');
        stdu="Singleton failed";
    }
    return stdu;
}


let ssig="gevindu";
let strsig=clientCodeDu();
let strsig1="geovindu";
let messagesig: string = 'Hello World,This is a typescript!,涂聚文 Geovin Du Web';
document.body.innerHTML = messagesig+","+strsig+","+strsig1+",TypeScript 单例模式"

 

調用:

<!doctype html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport"
        content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <head><title>TypeScript:单例模式</title>
      <meta name="Description" content="geovindu,涂聚文,Geovin Du"/>
<meta name="Keywords" content="geovindu,涂聚文,Geovin Du"/>
<meta name="author" content="geovindu,涂聚文,Geovin Du"/>  
    </head>
    <body>
        <script src="dist/Singletonts.js"></script>
    </body>
</html>

  

輸出:

 

npm install --save-dev ts-loader
npm install --save-dev webpack webpack-cli
npm install webpack

https://www.typescriptlang.org/docs/handbook/2/modules.html
https://www.typescriptlang.org/tsconfig#module