http请求中的caPath路径该如何指定？

requestHttp(url: string): Promise<string> { 
  //文件方式写入pem（导入证书需要放在rawfile资源目录下） 
  getContext(this).area = 0 
  let context: Context = getContext(this); 
  const keyPemConent = context.resourceManager.getRawFileContentSync('_.cnfic.com.cn.pem') 
  let filesDir: string = context.filesDir 
  let filePath = filesDir + "/testCer2.pem"; ///etc/ssl/certs/cacert.pem /storage/media/100/local/files/Docs/Download/charles-ssl-proxying-certificate.pem 
  let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE); 
  fs.writeSync(file.fd, keyPemConent.buffer); 
  fs.fsyncSync(file.fd); 
  fs.closeSync(file); 
 
  return new Promise((resolve, reject) => { 
  let httpRequest = http.createHttp(); 
  httpRequest.request( 
  url, 
  { 
  method: http.RequestMethod.GET, 
  connectTimeout: 60000, 
  readTimeout: 60000, 
  //抓包参数设置 
  usingProxy:true, 
  caPath :filePath , // "/data/local/tmp/NewFile.pem" 
}, (err: BusinessError, data) => { 
  console.info('1---- url:' + JSON.stringify(url)); 
  if (!err) { 
    // data.result为HTTP响应内容，可根据业务需要进行解析 
    console.info('1---- arrResult:' + JSON.stringify(data.result)); 
    let obj: object = JSON.parse(JSON.stringify(data.result)); 
    console.info('1---- header:' + JSON.stringify(data.header)); 
    console.info('1---- cookies:' + JSON.stringify(data.cookies)); 
    console.info('1---- code:' + JSON.stringify(data.responseCode)); 
    httpRequest.destroy(); 
  } else { 
    console.info('1---- error:' + JSON.stringify(err)); 
    console.info("1 ---------------------------------------------") 
    httpRequest.destroy(); 
  } 
}) 
}); 
}