什么是修饰器
--装饰器(Decorator)是一种特殊类型的声明，它能够被附加到类声明，方法， 访问符，属性或参数上.修饰器必是一个函数,用来修改类的行为

• 方法参数修饰器

function logParams(params: any) {
  return function (target: any, methodName: any, methodIndex: any) {
    console.log(params); //xxxx
    console.log(target); //方法原型
    console.log(methodName); ///方法名getData
    console.log(methodIndex); //方法参数索引
  };
}
function logParams2(params: any) {
  return function (target: any, methodName: any, methodIndex: any) {
    console.log(params); //xxxx
    console.log(target); //
    console.log(methodName); ///方法名getData
    console.log(methodIndex); //方法参数索引
  };
}
class HttpClient {
  constructor(public url: string) {}
  getDate(@logParams("xxxx") uuid: any, @logParams2("xoxo") id: number) {
    //从右到左执行顺序
    console.log(uuid);
  }
}
const http = new HttpClient("www.qkzer.com");
http.getDate("www.baidu.com", 5);

• 方法修饰器

function logMethod(params: any) {
  return function (target: any, methodName: any, desc: any): void {
    console.log(params); //修饰器实参 xxx
    console.log(target); //原型对象
    console.log(methodName); //方法名字  getData
    console.log(desc); //描述---可以进行改写方法
    desc.writable = false; //不可以被重写
    var temp = desc.value;
    desc.value = function (str: string): void {
      //str:方法参数
      console.log("修改" + "str");
      temp(str);
      temp.call(this, str);
      // desc.value();
    };
  };
}
function funaDorn(target: any, methodName: any, desc: any): void {
  console.log(target); //原型对象
  console.log(methodName); //方法名字  getData
  console.log(desc); //描述---可以进行改写方法
}
class goods {
  // @logClass('dddd')
  name: string | undefined;
  constructor(str?: string) {
    this.name = str;
  }
  @logMethod("xxxx")
  @funaDorn
  getData(str: string) {
    console.log(str); //d
  }
}
var d = new goods();
d.getData("d");

• 属性修饰器

function logClass(params:any){
    return function(target:any,attrName:any):void{
        console.log(params);//修饰器实参
        target[attrName] = '武器';//在原型链上附加属性
        console.log(target); //原型对象
        console.log(attrName);  //属性名字   
    }
}
class goods{
    @logClass('dddd')
    name:string | undefined
    constructor(str?:string){
        // this.name = str
    } 
}
var d = new goods();
console.log(d);
console.log(d.name);//武器

• 类修饰器

function logClass(target:any){
    console.dir(target);//原型
    return class extends target{ 
        public name:any
        getData(){ //重写类的方法
            console.log(this);
            console.log('新数据');
        }
    }
}
@logClass
class goods{
   public name:string | undefined
    constructor(str?:string){
        this.name = str
    } 
    getData(){
        console.log(this);
        console.log('原数据');
    }
}
var d = new goods();
d.getData()
console.log(d);