HarmonyOS 如何将SM2证书解析成X509Cert对象

export function convertDerDate(certData: string) { 
  let encodingBlob: certFramework.EncodingBlob = { 
    data: new util.Base64Helper().decodeSync(certData), 
    // 根据encodingData的格式进行赋值，支持FORMAT_PEM和FORMAT_DER 
    encodingFormat: certFramework.EncodingFormat.FORMAT_DER 
  }; 
  certFramework.createX509Cert(encodingBlob, (error, x509Cert) => { 
    try { 
      if (error != null) { 
      } else { 
        hilog.info(0x0000, TAG, 'createX509Cert success'); 
        let subjectName = x509Cert.getSubjectName() 
        let result = util.TextDecoder.create('utf-8', { ignoreBOM: true }); 
        let arrayString = result.decodeWithStream(subjectName.data, { stream: false }); 
      } 
    } catch (err) { 
      let e: BusinessError = err as BusinessError; 
      hilog.info(0x0000, TAG, 'getNotBeforeTime failed, errCode: ' + e.code + ', errMsg: ' + e.message); 
    } finally { 
    } 
  }); 
}