如何通过AOP统计方法执行时间

function addTimePrinter(targetClass: Object, methodName: string, isStatic: boolean, isNanoseconds:boolean) { 
  let t1 = 0; 
  let t2 = 0; 
  util.Aspect.addBefore(targetClass, methodName, isStatic, () => { 
    t1 = systemDateTime.getTime(isNanoseconds); 
  }) 
  util.Aspect.addAfter(targetClass, methodName, isStatic, () => { 
    t2 = systemDateTime.getTime(isNanoseconds); 
    console.log("t2 - t1 = " + (t2 - t1).toString()); 
  }) 
} 
 
class Utils { 
  Add(len:number) :number{ 
    let num = 0; 
    for (let index = 1; index <= len; index++) { 
      num += index 
    } 
    return num 
  } 
} 
 
addTimePrinter(Utils, 'Add', false, true); 
let m = new Utils(); 
m.Add(10000);