HarmonyOS 多层动态嵌套JSON如何取值

示例demo：

interface Key3Item {
  key4: string
  key5?: string
  key6: Record<string, ESObject>
}

interface Key1Item {
  key3: Array<Key3Item>
}
class ResponseResult {
  key1: Key1Item = {
    key3:[]
  }
  key2: number = 0;
  constructor() {
  }
}
@Entry
@Component
struct Index {
  aboutToAppear(): void {
    let result: string = '{"key1":{"key3":[{"key4":"zhangsan","key5":19 }]},"key2":10000}'
    if (result) {
      //ResponseResult 为用于接收数据的实体类：
      let jsonObj: ResponseResult = JSON.parse(result)
      console.log('ResponseResult' + jsonObj.key1.key3[0].key4)
    }
  }
  build() {
  }
}