如何获取工程目录下的json文件？

import { Context } from '@ohos.abilityAccessCtrl'; 
import buffer from '@ohos.buffer'; 
 
@Entry 
@Component 
struct Index { 
  private context: Context = getContext(this); 
  private str:string  getRawFile(): ESObject { 
  //调用getRawFileContent接口获取json文件内容，并读为string  
  getContext(this).resourceManager.getRawFileContent("test.json", (err, data) => { 
    try { 
      this.str = buffer.from(data.buffer).toString(); 
    } catch (e) { 
      console.info(JSON.stringify(e)) 
    } 
  }) 
  //也可以调用getRawFileContentSync接口获取json文件内容，并读为string  
  try { 
    let data: Uint8Array = this.context.resourceManager.getRawFileContentSync("test.json"); 
    this.str = buffer.from(data.buffer).toString(); 
  } catch (e) { 
    console.info(JSON.stringify(e)) 
  } 
  // string转为ESObject  
  let obj: ESObject = JSON.parse(this.str) 
  return obj 
} 
 
  build() { 
    Column() { 
      Button("get").onClick(() => { 
        this.getRawFile() 
      }) 
    }.width('100%') 
  } 
}