base64字符串如何转为图片并保存

import { buffer } from '@kit.ArkTS'; 
import { fileIo } from '@kit.CoreFileKit'; 
import { common } from '@kit.AbilityKit'; 
import { fileUri } from "@kit.CoreFileKit"; 
import { hilog } from '@kit.PerformanceAnalysisKit'; 
 
let context = getContext(this) as common.UIAbilityContext; 
let filesDir = context.filesDir; 
 
// data为需要转换的base64字符串，返回沙箱路径uri 
export async function writeFile(data: string): Promise<string> { 
  let uri = '' 
  try { 
    let filePath = filesDir + "/1.png"; 
    uri = fileUri.getUriFromPath(filePath); 
    let file = fileIo.openSync(filePath, fileIo.OpenMode.READ_WRITE | fileIo.OpenMode.CREATE); 
    console.info("file fd: " + file.fd); 
    const reg = new RegExp("data:image/\\w+;base64,") 
    const base64 = data.replace(reg, ""); 
    console.log("base64flag", base64) 
    const dataBuffer = buffer.from(base64, 'base64') 
    let writeLen = fileIo.writeSync(file.fd, dataBuffer.buffer); 
    hilog.info(0xA0c0d0,'uri',uri) 
    fileIo.closeSync(file); 
  } 
  catch (Error) { 
    hilog.error(0xA0c0d0,'Error',Error.code) 
  } 
  return uri; 
}