一種angular的方法級的緩存注解（裝飾器）

@Cacheable(value="'accountCache_'+#userName")// 緩存名叫 accountCache_USERNAME 
public Account getAccountByName(String userName) { 
// @@@@
return acount; 
}

@cacheable(111)
getSecondLeftMenu(topMenuId: number){
return 1111;
}

export function cacheable(timeout:number) {
 return function (target: any, key: string, descriptor: any) {
 const originalMethod = descriptor.value;
 descriptor.value = function (...args: any[]) {
//把傳入的參數(shù)和被調(diào)的函數(shù)名一起組成存儲的主鍵
 const paramStr = args.map(a => JSON.stringify(a)).join();
 const keyStr=key+"start$$"+(paramStr||"")+"-$$end";
 let resultStr=localStorage.getItem(keyStr);
 if (!!resultStr) {
 let resultValue=JSON.parse(resultStr);
 let now=new Date() as any;
//把緩存時的時間和當前的時間進行對比，如果沒有超時，則直接返回
 let old2=(new Date(resultValue.date)) as any;
 let delt=now - old2;
 if (delt<(timeout*1000)) {
 return Promise.resolve(resultValue.value);
 }
 }
//超時時，調(diào)用原方法，并記錄返回結(jié)果，這里我們的返回均是promise對象
 var result = originalMethod.apply(this, args);
 result.then(data=>{
 let dd={
 date:new Date(),
 value:data
 }
 localStorage.setItem(keyStr,JSON.stringify(dd))
 return Promise.resolve(data);
 },data=>{
 return Promise.reject(data);
 })
 return result;
 }
 return descriptor;
 }
}