# 如何判断能否对接口进行插桩或替换

如果类和方法在运行时是实际存在的对象，并且方法的属性描述符的writable字段为true，即可对接口进行插桩和替换。

获取方法的属性描述符的writable字段：

创建ObjectUtil工具类，实现ObjectGetOwnPropertyDescriptor方法。

```ts
export class ObjectUtil {
  static ObjectGetOwnPropertyDescriptor(o: any, p: PropertyKey): PropertyDescriptor | undefined{
    return Object.getOwnPropertyDescriptor(o, p)
  }
}
```

调用工具类的方法，获取方法的属性描述符：

```ts
import { ObjectUtil } from '../utils/ObjectUtil'

class Test {
  static data: string = "initData";
  static printData(): void {
    console.log("execute original printData");
  }
}

@Entry
@Component
export  struct AOPReplaced {
  @State message: string = 'Hello World';

  build() {
    Row() {
      Column() {
        Text(this.message)
          .fontSize(50)
          .fontWeight(FontWeight.Bold)
          .onClick(() => {
          // Obtain the property descriptor of myMethod
            let des = ObjectUtil.ObjectGetOwnPropertyDescriptor(Test, 'printData')
            console.log('des',JSON.stringify(des))
           // Determine whether the writable field is true
            if (des && des.writable) {
              console.log('Method is writable');
            } else {
              console.log('Method is not writable or does not exist');
            }
          })
      }
      .width('100%')
    }
    .height('100%')
  }
}
```