网站原图怎么做外包公司值得去吗
目录
1、Class类
1.1 Class类 实例属性
1.2 Class类 构造函数
1.3 Class类 定义方法
1.4 静态属性 和 静态方法
1.5 继承 extends 和 super 关键字
1.6 instanceof 检测是否实例
1.7.修饰符(readonly、private、protected 、public)
1.7.1 readonly
1.7.2 Private
1.7.3 protected
1.7.4 public
2、剩余参数和展开运算符
2.1 剩余参数语法
2.2 剩余参数和展开运算符
3、接口补充
3.1 接口继承
3.2 接口实现
4、泛型
4.1 泛型函数
4.2 泛型约束
4.3 多个泛型参数
4.4 泛型接口
4.5 泛型类
前言：ArkTS语法进阶Class、剩余参数和展开运算符，同时包含对接口的补充说明、泛型
1、Class类
1.1 Class类 实例属性
注意定义类要设置初始值，不设置初始值要设置为可选字段 使用符号？
import window from '@ohos.window';class Cat {name: string = 'Tom'foods?: string
}// 基于类创建对象
let p: Cat = new Cat()
p.foods = 'sss'
console.log(p.name)
@Entry
@Component
struct Index {@State message: string = '@春天的菠菜';onPageShow(): void {window.getLastWindow(AppStorage.get("context"), (err, data) => {if (err.code) {console.error('Failed to get last window. Cause:' + JSON.stringify(err));return;}data.setFullScreen(true)});}build() {Column(){Text(p.name +'****'+ p.foods+'****'+ p.foods?.length).fontSize(20).fontWeight(700).backgroundColor(Color.Green).padding(10)}.width('100%').height(100)}
} 
1.2 Class类 构造函数
import window from '@ohos.window';
@Extend(Text)
function textExtend(){.fontSize(20).fontWeight(700).backgroundColor(Color.Green).padding(10).margin(5)
}// 1 构造函数语法
class Food {name: stringprice: numberconstructor(name:string, price:number) {this.name = namethis.price = price}
}let f1 = new Food('西红柿', 2.23)
let f2= new Food('面条', 15.00)//********************************************************
interface iCat{name: stringprice: numberdesc: string
}// 多参数传参合并
class Cat {name: stringprice: numberdesc: stringconstructor(paramsObj: iCat) {this.name = paramsObj.namethis.price = paramsObj.pricethis.desc = paramsObj.desc}
}let p1: Cat = new Cat({name: '波斯猫',desc: '珀斯的猫',price: 123222
})@Entry
@Component
struct Index {@State message: string = '@春天的菠菜';onPageShow(): void {window.getLastWindow(AppStorage.get("context"), (err, data) => {if (err.code) {console.error('Failed to get last window. Cause:' + JSON.stringify(err));return;}data.setFullScreen(true)});}build() {Column(){Text(f1.name +'****'+ f1.price+'元').textExtend()Text(f2.name +'****'+ f2.price+'元').textExtend()Text(p1.name +'****'+ p1.price+'元'+'****'+p1.desc).textExtend()}.width('100%').height(100)}
} 
1.3 Class类 定义方法
import window from '@ohos.window';
@Extend(Text)
function textExtend(){.fontSize(20).fontWeight(700).backgroundColor(Color.Green).padding(10).margin(5)
}class Person {name: stringage: numberconstructor(name: string,age: number) {this.name = namethis.age = age}// 类方法sayHi(yorName:string){return ('Hello!' + yorName + '我是' + this.name)}
}let p1: Person = new Person('波斯猫', 18)@Entry
@Component
struct Index {@State message: string = '@春天的菠菜';onPageShow(): void {window.getLastWindow(AppStorage.get("context"), (err, data) => {if (err.code) {console.error('Failed to get last window. Cause:' + JSON.stringify(err));return;}data.setFullScreen(true)});}build() {Column(){Text(p1.name +'****'+ p1.sayHi('春天的菠菜')).textExtend()}.width('100%').height(100)}
} 
1.4 静态属性 和 静态方法
import window from '@ohos.window';
@Extend(Text)
function textExtend(){.fontSize(20).fontWeight(700).backgroundColor(Color.Green).padding(10).margin(5)
}class Robot {static version: string = 'V2.0'static getRandom():number{return Math.random()}}@Entry
@Component
struct Index {@State message: string = '@春天的菠菜';onPageShow(): void {window.getLastWindow(AppStorage.get("context"), (err, data) => {if (err.code) {console.error('Failed to get last window. Cause:' + JSON.stringify(err));return;}data.setFullScreen(true)});}build() {Column(){Text(Robot.version +'****'+ Robot.getRandom()).textExtend()}.width('100%').height(100)}
}
1.5 继承 extends 和 super 关键字
import window from '@ohos.window';
@Extend(Text)
function textExtend(){.fontSize(20).fontWeight(700).backgroundColor(Color.Green).padding(10).margin(5)
}class Person {name: stringage: numberconstructor(name:string, age:number) {this.name =namethis.age = age}sayHi(): string{return 'Hello!'}}
class Student extends Person{grade: stringconstructor(name:string, age:number,grade: string) {// 父类中的构造函数super(name,age)this.grade = grade}// 子类想要重写父类的方法，只需提供同名的方法即可sayHi(): string{super.sayHi() // 保留了父类的，又新增了自己的return 'Student HI!'}study (): string {return '我爱学习'}}
class Teacher extends Person{}
class Worker extends Person{}let s1: Student = new Student('张三',18,'五年级')
let t1: Teacher = new Teacher('李四',32)
let w1: Worker = new Worker('王五', 46)@Entry
@Component
struct Index {@State message: string = '@春天的菠菜';onPageShow(): void {window.getLastWindow(AppStorage.get("context"), (err, data) => {if (err.code) {console.error('Failed to get last window. Cause:' + JSON.stringify(err));return;}data.setFullScreen(true)});}build() {Column(){Text( s1.name+ s1.sayHi()+s1.grade+s1.study()+'****'+ t1.name+t1.sayHi()).textExtend()}.width('100%').height(100)}
} 
1.6 instanceof 检测是否实例
// console.log(typeof 111)
// console.log(typeof true)
// console.log(typeof 'abc')
//
// // typeof 仅能用于判断简单类型, 复杂类型需要用instanceof判断
// class Person {}
// class Student {}
// let p: Person = new Person()
// let s: Student = new Student()
// console.log(typeof p)
// console.log(typeof s)class Person {}
class Student extends Person {}
class Worker extends Person {}let s: Student = new Student()
console.log('判断结果:', s instanceof Student)
console.log('判断结果:', s instanceof Person)
console.log('判断结果:', s instanceof Worker)interface IObj {}
// 判断一个变量是否存的是数组
let temp: IObj = {}
console.log('是否是数组', temp instanceof Array)@Entry
@Component
struct Index {build() {// Row().width(100)Column() {}}
}1.7.修饰符(readonly、private、protected 、public)
1.7.1 readonly
// 修饰符 readonly
class Cat {name: stringage: numberreadonly legs: number = 4constructor(name: string, age: number) {this.name = namethis.age = age}
}
let c1 = new Cat('小花', 2)
c1.name = '小美'
// c1.legs = 6 // 不能修改
console.log('姓名:', c1.name)// 3.1415926 圆周率
// Math.PI@Entry
@Component
struct Index {build() {// Row().width(100)Column() {}}
}1.7.2 Private
// class Person {
// private name: string = ''
// private age: number = 0
// desc: string = '描述'
// }
// let p = new Person()
// console.log('实例访问:', p.name) // 无法再外部访问私有数据// class Student extends Person {
// sayHi () {
// console.log('访问私有的数据:', super.name) // 私有数据无法再(子类)访问
// }
// }@Entry
@Component
struct Index {build() {// Row().width(100)Column() {}}
}1.7.3 protected
1.7.4 public
class Person {protected name: stringprotected age: numberdesc: string = '描述'// 类的内容, 无论是私有还是保护, 都是可以访问的constructor(name: string, age: number) {this.name = namethis.age = age}
}
let p = new Person('小王', 18)
// console.log('实例访问:', p.name) // 无法在外部, 访问受保护的数据class Student extends Person {sayHi () {console.log('访问私有的数据:', super.name) // 保护的数据可以在子类访问}
}@Entry
@Component
struct Index {build() {// Row().width(100)Column() {}}
}2、剩余参数和展开运算符
2.1 剩余参数语法
// ... 展开运算符, 用于数组的平铺合并
let arr1: number[] = [1,2,3]
let arr2: number[] = [4,5,6]
let newArr: number[] = [...arr1, ...arr2]
console.log('最终的数组', newArr)@Entry
@Component
struct Index {build() {Column() {}}
}2.2 剩余参数和展开运算符
合并数组
// ... 展开运算符, 用于数组的平铺合并
let arr1: number[] = [1,2,3]
let arr2: number[] = [4,5,6]
let newArr: number[] = [...arr1, ...arr2]
console.log('最终的数组', newArr)@Entry
@Component
struct Index {build() {Column() {}}
}3、接口补充
3.1 接口继承
interface IAnimal {name: stringage: number
}
interface ICat extends IAnimal {hair: string
}
interface IDog extends IAnimal {color: string
}
let dog1: IDog = {name: '小泰迪',age: 2,color: '棕色'
}@Entry
@Component
struct Index {build() {Column() {}}
}3.2 接口实现
// 接口实现: 定义一个接口, 约束类 => 类需要按照接口的要求, 实现类的主体
interface IDog {name: stringage: numberjump: () => void
}// 基于接口, 实现类
class Dog implements IDog {name: stringage: numberdesc: stringconstructor(name: string, age: number, desc: string) {this.name = namethis.age = agethis.desc = desc}jump() {}
}
let dog: Dog = new Dog('小飞', 2, '是一只非常帅气的二哈')
dog.jump()function 函数名<Type>(temp:Type):Type{return temp
}@Entry
@Component
struct Index {build() {Column() {}}
}4、泛型
4.1 泛型函数
// 泛型: 广泛的类型 => 类型可以作为参数传递过来, 类型是[可变]的
// function 函数名<Type> (形参: Type): Type {
// return 形参
// }// 封装了一个函数: 传入什么样的参数, 就立刻返回什么样的参数
function fn<T> (param: T) : T {return param
}
fn<string>('abc')
fn<number>(123)
fn<boolean>(true)
fn<number[]>([1, 2, 3, 4, 5])// 会默认根据传参, 进行类型推断, 动态的配置 T 类型参数 的值
fn(true)
fn([1, 2, 3, 4, 5])// 练习1: 定义函数, 参数是数组(存的类型不定), 返回数组的长度
function getLength<T> (arr: T[]) : number {return arr.length
}
console.log('', getLength<number>([1, 2, 3]))
console.log('', getLength<string>(['1', 'aa', 'bb', 'cc']))// 练习2: 定义函数, 参数是数组(存的类型不定), 返回数组的最后一项
function getLast<T> (arr: T[]) : T {return arr[arr.length - 1]
}
console.log('', getLast<number>([1, 2, 3, 4, 99]))
console.log('', getLast<string>(['a', 'b', 'c']))@Entry
@Component
struct Index {build() {Column() {}}
}4.2 泛型约束
// 泛型约束: 给传递的类型参数, 添加限制
interface ILength {length: number
}
function fn<T extends ILength>(param: T) {console.log('', param.length)
}fn<string>('abc')
fn<number[]>([1, 2, 3])class Desk {length = 2
}
let d = new Desk()
fn<Desk>(d)@Entry
@Component
struct Index {build() {Column() {}}
}4.3 多个泛型参数
// 多个泛型变量 => 传递多个类型参数
function fn<T1, T2> (param1: T1, param2: T2) {console.log('参数1', param1)console.log('参数2', param2)
}
fn<string, boolean>('abc', true)
fn<number, string>(123, 'abc')
fn<string[], number[]>(['a', 'b'], [1, 2])@Entry
@Component
struct Index {build() {Column() {}}
}新版本已经能自动识别
4.4 泛型接口
// 泛型接口
interface IdFunc<T> {// 约定有两个方法 (id类型不定, string number)// 1. 传入 id 值, 就返回 id 值// 2. 返回一个 ids 数组id: (value: T) => Tids: () => T[]
}let obj: IdFunc<number> = {id(value: number) {return value},ids() {return [1, 2, 3]}
}let obj2: IdFunc<string> = {id(value: string) {return value},ids() {return ['001', '002', '003']}
}@Entry
@Component
struct Index {build() {Column() {}}
}4.5 泛型类
// 泛型类: 定义类的时候, 配合泛型一起定义
class Person <T>{id: Tconstructor(id: T) {this.id = id}getId (): T {return this.id}
}
let p: Person<number> = new Person<number>(10)
let p2: Person<string> = new Person<string>('abc')@Entry
@Component
struct Index {build() {Column() {}}
}