TypeScript 类

传统的js是使用函数和原型链的方式用来模拟类

es6中加入了类,class关键字

// 定义类
class Greeter {
    greeting: string;
    constructor(message: string){
        this.greeting = message;    // 使用this表示访问的是类成员 
    }
    greet() {
        return "Hello," + this.greeting;
    }
}

// 创建对象
let greeter = new Greeter("World");

编译后的js文件如下
es5

// 定义类
var Greeter = /** @class */ (function () {
    function Greeter(message) {
        this.greeting = message;
    }
    Greeter.prototype.greet = function () {
        return "Hello," + this.greeting;
    };
    return Greeter;
}());
// 创建对象
var greeter = new Greeter("World");
//# sourceMappingURL=out.js.map

es6

// 定义类
class Greeter {
    constructor(message) {
        this.greeting = message;
    }
    greet() {
        return "Hello," + this.greeting;
    }
}
// 创建对象
let greeter = new Greeter("World");
//# sourceMappingURL=out.js.map

继承

在ts中可以使用类似于Java中的类的继承。

// 定义类
class Animal {
    move(distanceInMeters: number = 0) {    // 定义一个方法
        console.log("class - Animal move 方法" + distanceInMeters);
    }
}

// 定义继承类
class Dog extends Animal {
    bark() {
        console.log("Dog!");
    }
}

const dog = new Dog();    // 创建给予Dog类的对象
dog.bark();    // 调用继承类的方法bark()
dog.move(10);    // 调用父类的move方法
dog.bark();
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    }
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
// 定义类
var Animal = /** @class */ (function () {
    function Animal() {
    }
    Animal.prototype.move = function (distanceInMeters) {
        if (distanceInMeters === void 0) { distanceInMeters = 0; }
        console.log("class - Animal move 方法" + distanceInMeters);
    };
    return Animal;
}());
// 定义继承类
var Dog = /** @class */ (function (_super) {
    __extends(Dog, _super);
    function Dog() {
        return _super !== null && _super.apply(this, arguments) || this;
    }
    Dog.prototype.bark = function () {
        console.log("Dog!");
    };
    return Dog;
}(Animal));
var dog = new Dog(); // 创建给予Dog类的对象
dog.bark(); // 调用继承类的方法bark()
dog.move(10); // 调用父类的move方法
dog.bark();
//# sourceMappingURL=out.js.map

超类

class Animal {
    name: string;
    constructor(theName: string){
        this.name = theName;
    }
    move(distanceInMeters: number = 0){
        console.log("distanceInMeters " + distanceInMeters);
    }
}

class Snake extends Animal {
    constructor(name: string){
        super(name);    // 调用父类的构造方法,在构造函数访问this之前,必须调用一次 super()
    };
    move(distanceInMeters = 45){    // 重写父类的move方法
        console.log("Galloping...");
        super.move(distanceInMeters);    // 调用父类的move方法
    }
};

class Horse extends Animal {
    constructor(name: string){
        super(name);    // 调用父类的构造方法
    }
    move(distanceInMeters = 45){    // 重写move方法
        console.log("Galloping...");
        super.move(distanceInMeters);    // 调用父类的move
    }
}

// 调用基类的派生类即Snake类,使用的是基类的构造方法,重写了基类的move方法,并在子类的move方法中调用了父类的move方法
let sam = new Snake("Sammy the Python");
let tom: Animal;    // 声明tom对象,其为Animal类
tom = new Horse("Tommy the Palomino");    // 此处赋值为Horse类,重写了Animal中的move方法

sam.move();
tom.move();
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    }
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
var Animal = /** @class */ (function () {
    function Animal(theName) {
        this.name = theName;
    }
    Animal.prototype.move = function (distanceInMeters) {
        if (distanceInMeters === void 0) { distanceInMeters = 0; }
        console.log("distanceInMeters " + distanceInMeters);
    };
    return Animal;
}());
var Snake = /** @class */ (function (_super) {
    __extends(Snake, _super);
    function Snake(name) {
        return _super.call(this, name) || this;
    }
    ;
    Snake.prototype.move = function (distanceInMeters) {
        if (distanceInMeters === void 0) { distanceInMeters = 45; }
        console.log("Galloping...");
        _super.prototype.move.call(this, distanceInMeters); // 调用父类的move方法
    };
    return Snake;
}(Animal));
;
var Horse = /** @class */ (function (_super) {
    __extends(Horse, _super);
    function Horse(name) {
        return _super.call(this, name) || this;
    }
    Horse.prototype.move = function (distanceInMeters) {
        if (distanceInMeters === void 0) { distanceInMeters = 45; }
        console.log("Galloping...");
        _super.prototype.move.call(this, distanceInMeters); // 调用父类的move
    };
    return Horse;
}(Animal));
// 调用基类的派生类即Snake类,使用的是基类的构造方法,重写了基类的move方法,并在子类的move方法中调用了父类的move方法
var sam = new Snake("Sammy the Python");
var tom; // 声明tom对象,其为Animal类
tom = new Horse("Tommy the Palomino"); // 此处赋值为Horse类,重写了Animal中的move方法
sam.move();
tom.move();
//# sourceMappingURL=out.js.map

公有私有,保护修饰符

public 默认

public为默认

class Animal {
    public name: string;
    public constructor(theName: string){
        this.name = theName;
    }
    public move(distanceInMeters: number){
        console.log("move 方法");
    }
}
var Animal = /** @class */ (function () {
    function Animal(theName) {
        this.name = theName;
    }
    Animal.prototype.move = function (distanceInMeters) {
        console.log("move 方法");
    };
    return Animal;
}());
//# sourceMappingURL=out.js.map

private 保护成员

不能被外部访问
TypeScript 类

class Person {
    protected name: string;    // 保护成员,对外不可访问
    constructor(name:string){
        this.name = name;
    }
}

class Employee extends Person {
    private department: string;

    constructor(name:string, department:string){
        super(name);    // 调用父类的构造方法
        // 接着才能使用this
        this.department = department;
    }

    public getElevatorPitch(){
        return "hello !" + name;    // 通过实例访问父类的name
    }
}

let howard = new Employee("Howard", "sales");
console.log(howard.getElevatorPitch());
//console.log(howard.name);    //访问父类的,失败,不能直接被访问,但是能被派生方法所访问
PS C:\Users\mingm\Desktop\ts> tsc
Active code page: 65001
PS C:\Users\mingm\Desktop\ts>
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    }
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
var Person = /** @class */ (function () {
    function Person(name) {
        this.name = name;
    }
    return Person;
}());
var Employee = /** @class */ (function (_super) {
    __extends(Employee, _super);
    function Employee(name, department) {
        var _this = _super.call(this, name) || this;
        // 接着才能使用this
        _this.department = department;
        return _this;
    }
    Employee.prototype.getElevatorPitch = function () {
        return "hello !" + name; // 通过实例访问父类的name
    };
    return Employee;
}(Person));
var howard = new Employee("Howard", "sales");
console.log(howard.getElevatorPitch());
//console.log(howard.name);    //访问父类的,失败,不能直接被访问,但是能被派生方法所访问
//# sourceMappingURL=out.js.map
// 构造函数使用保护
class Person {
    protected name: string;
    protected constructor(theName:string){    // 构造方法,进行保护
        this.name = theName;
    }
}

class Employee extends Person {
    private department: string;

    constructor(name: string, department:string){
        super(name);
        this.department = department;
    }

    public getElevatorPitch() {
        return "hello" + this.department + this.name;
    }
}

let howard = new Employee("Howard", "Sales");

//let john = new Peron("John");    //错误,构造函数被保护,不能在外部访问
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    }
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
// 构造函数使用保护
var Person = /** @class */ (function () {
    function Person(theName) {
        this.name = theName;
    }
    return Person;
}());
var Employee = /** @class */ (function (_super) {
    __extends(Employee, _super);
    function Employee(name, department) {
        var _this = _super.call(this, name) || this;
        _this.department = department;
        return _this;
    }
    Employee.prototype.getElevatorPitch = function () {
        return "hello" + this.department + this.name;
    };
    return Employee;
}(Person));
var howard = new Employee("Howard", "Sales");
//let john = new Peron("John");    //错误,构造函数被保护,不能在外部访问
//# sourceMappingURL=out.js.map

readonly修饰符

将属性设置为只读

class Octopus {
    readonly name: string;    // 只读
    readonly numberOfLegs: number = 8; // 只读

    constructor(theName:string){
        this.name = theName;
    }
}
let dad = new Octopus("Hello world");

//dad.name = "Hello world";    //设置值。出错,由于为只读
var Octopus = /** @class */ (function () {
    function Octopus(theName) {
        this.numberOfLegs = 8; // 只读
        this.name = theName;
    }
    return Octopus;
}());
var dad = new Octopus("Hello world");
//dad.name = "Hello world";    //设置值。出错,由于为只读
//# sourceMappingURL=out.js.map

参数属性

class Octopus {
    readonly numberOfLegs: number = 9;
    constructor(readonly name:string){    // 直接定义参数属性

    }
}
var Octopus = /** @class */ (function () {
    function Octopus(name) {
        this.name = name;
        this.numberOfLegs = 9;
    }
    return Octopus;
}());
//# sourceMappingURL=out.js.map

通过get set获取属性

let passcode = "secret passcode";

class Employee {
    private _fullName: string;    // 保护成员一般下划线

    get fullName():string {    // get方法
        return this._fullName;
    }

    set fullName(newName:string){
        if (passcode && passcode == "code") {
            // 进行赋值操作
            this._fullName = newName;
        }else {
            console.log("出现重复")
        }
    }
}

let employee = new Employee();    // 创建对象
employee.fullName = "Bob";    //调用get方法
// 下面调用set方法
if(employee.fullName){
    console.log(employee.fullName);
}
PS C:\Users\mingm\Desktop\ts> tsc
Active code page: 65001
PS C:\Users\mingm\Desktop\ts>
var passcode = "secret passcode";
var Employee = /** @class */ (function () {
    function Employee() {
    }
    Object.defineProperty(Employee.prototype, "fullName", {
        get: function () {
            return this._fullName;
        },
        set: function (newName) {
            if (passcode && passcode == "code") {
                // 进行赋值操作
                this._fullName = newName;
            }
            else {
                console.log("出现重复");
            }
        },
        enumerable: true,
        configurable: true
    });
    return Employee;
}());
var employee = new Employee(); // 创建对象
employee.fullName = "Bob"; //调用get方法
// 下面调用set方法
if (employee.fullName) {
    console.log(employee.fullName);
}
//# sourceMappingURL=out.js.map

只能输出es5或更高的版本,不支持输出es3

静态属性

当类未被实例化的时候,可以直接访问的为静态属性

class Grid {
    static origin = { x: 0, y: 0 };    // 这里类似使用static 
    calculate(point:{x:number, y:number}){    // 在此处定义了point,
        let x = point.x - Grid.origin.x    // 前面访问的是poinyt定义的,后面访问的是static定义的origin
        let y = point.y - Grid.origin.y;    // 同理如上
        return point.x + point.y;    
    }
    constructor(public scale: number) { };
}

let grid1 = new Grid(1.0);// 对static进行赋值
let grid2 = new Grid(2.0);

// 访问
grid1.calculate({x:10, y:10});    
grid2.calculate({x:10, y:10});
var Grid = /** @class */ (function () {
    function Grid(scale) {
        this.scale = scale;
    }
    Grid.prototype.calculate = function (point) {
        var x = point.x - Grid.origin.x; // 前面访问的是poinyt定义的,后面访问的是static定义的origin
        var y = point.y - Grid.origin.y; // 同理如上
        return point.x + point.y;
    };
    ;
    Grid.origin = { x: 0, y: 0 }; // 这里类似使用static 
    return Grid;
}());
var grid1 = new Grid(1.0); // 对static进行赋值
var grid2 = new Grid(2.0);
// 访问
grid1.calculate({ x: 10, y: 10 });
grid2.calculate({ x: 10, y: 10 });
//# sourceMappingURL=out.js.map

抽象类

抽象类为其他派生类的基类。

抽象类不会被实例化

抽象类用于作为基类,派生出其他类使用。

// 定义抽象类
abstract class Department {
    constructor(public name:string){

    }

    // 定义实现的细节
    printName():void{
        console.log("实现细节");
    }

    // 定义抽象方法,该抽象方法必须在派生类中实现其具体的内容
    abstract printMeeting(): void;
}

class AccountingDepartemnt extends Department {
    constructor(){
        super("hello world");    // 调用基类的构造方法
    }

    // 对抽象方法进行完善
    printMeeting():void{
        console.log("完善!");
    }

    // 定义其余的方法
    generateReports():void{
        console.log("添加的其他方法")
    }
}

// 创建一个抽象类型的引用
let department: Department;    // 抽象类的引用,类似于定义,可以被抽象类的子类进行实例化,即分配内存空间,不能被抽象类进行实例化,因为抽象类不能分配内存空间,所以不能对抽象类进行new操作
department = new AccountingDepartemnt();    // 可以进行分配内存空间
department.printMeeting();
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    }
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
// 定义抽象类
var Department = /** @class */ (function () {
    function Department(name) {
        this.name = name;
    }
    // 定义实现的细节
    Department.prototype.printName = function () {
        console.log("实现细节");
    };
    return Department;
}());
var AccountingDepartemnt = /** @class */ (function (_super) {
    __extends(AccountingDepartemnt, _super);
    function AccountingDepartemnt() {
        return _super.call(this, "hello world") || this;
    }
    // 对抽象方法进行完善
    AccountingDepartemnt.prototype.printMeeting = function () {
        console.log("完善!");
    };
    // 定义其余的方法
    AccountingDepartemnt.prototype.generateReports = function () {
        console.log("添加的其他方法");
    };
    return AccountingDepartemnt;
}(Department));
// 创建一个抽象类型的引用
var department; // 抽象类的引用,类似于定义,可以被抽象类的子类进行实例化,即分配内存空间,不能被抽象类进行实例化,因为抽象类不能分配内存空间,所以不能对抽象类进行new操作
department = new AccountingDepartemnt(); // 可以进行分配内存空间
department.printMeeting();
//# sourceMappingURL=out.js.map

构造函数

可以使用类似于java中的语法,进行声明构造函数

class Greeter{
    greeting: string;
    constructor(message:string){
        this.greeting = message;
    }
    // 类似于java中声明构造方法
    greet(){
        return "hello " + this.greeting;
    }
}

// 首先进行创建引用,类似于原生的var,仅仅声明,并未创建引用。但是必须进行声明,声明其为Greeter
let greeter: Greeter;
// 进行分配空间
greeter = new Greeter("world");
console.log(greeter.greet());

和使用抽象接口一样,当使用抽象接口的时候,必须要进行先创建引用,然后在分配空间
原生的如下

var i;  // 在栈上开辟一块空间,进行储存
i = new Greeter();  // 完成由栈到堆的指向,对象储存在堆中,当然啦,C++允许对象储存在栈中

必须进行两步。

关于C++堆和栈的类

静态建立

使用

Box Box

如上的方式,将会静态的建立一个对象
静态建立对象,将会由编译器在栈中分配内存空间。通过移动栈顶指针,挪出适当的位置,在内存空间上调用构造函数,形成一个栈对象,此方法为在栈中储存对象。

动态建立

使用

Box* Box = new Box();

如上的方式,将会动态的建立一个对象。
使用new操作运算符的时候,将会在堆中分配一块内存空间,完成由栈到对的指向。

类当做接口使用

接口,一种传入对象的规范,比喻,水管的水龙头。

类可以创建出任何类型

class Point{
    x: number;
    y: number;
}

interface Point3d extends Point{
    z: number;
}

let point3d:Point3d = {
    x:1,
    y:2,
    z:4
}

使用extends,进行创建接口

var Point = /** @class */ (function () {
    function Point() {
    }
    return Point;
}());
var point3d = {
    x: 1,
    y: 2,
    z: 4
};
//# sourceMappingURL=out.js.map

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