HarmonyOS 5.0 应用开发——文件读写

//同步创建目录fileIo.mkdirSync(this.context.cacheDir+'/pili')

let path=this.context.cacheDir+'/pili'// 如果文件可以使用if(fileIo.accessSync(path)){
  if(fileIo.statSync(path).isFile())  {//删除该文件    fileIo.unlinkSync(path)  }else if(fileIo.statSync(path).isDirectory()){    //删除该目录    fileIo.rmdirSync(path)  }}

let path=this.context.cacheDirlet file=fileIo.openSync(path,fileIo.OpenMode.READ_ONLY)// 父级目录let parent_path=file.getParent()// 按照过滤规则扫描出文件相对路径let files=fileIo.listFileSync(parent_path,{recursion:true,filter:{suffix:['.jpg']}})console.log('gxxt ',JSON.stringify(files));

// 打开文件let file=fileIo.openSync(this.context.cacheDir+'/test.txt',fileIo.OpenMode.CREATE|fileIo.OpenMode.WRITE_ONLY)// 同步写入文本fileIo.writeSync(file.fd,'写入的测试文本')// 关闭文件fileIo.closeSync(file.fd)

// 打开文件let file = fileIo.openSync(this.context.cacheDir + '/test.txt', fileIo.OpenMode.CREATE | fileIo.OpenMode.READ_ONLY)// 根据文件大小创建缓存区let buffer1 = new ArrayBuffer(fileIo.statSync(file.fd).size)// 将文本读取进入缓存区并返回读出的字节个数let len = fileIo.readSync(file.fd, buffer1)//将字节数组转化为buffer对象let textbuffer = buffer.from(buffer1, 0, len)console.log('gxxt ',textbuffer.toString('utf-8'))

// 直接读取文件返回字符串let text:string=fileIo.readTextSync(this.context.cacheDir + '/test.txt',{encoding:'utf-8'})console.log('gxxt ',text)

// 获取文件行的迭代器let iter = fileIo.readLinesSync(this.context.cacheDir + '/test.txt', { encoding: 'utf-8' })let lines:string[]=[]// 迭代器往下是否能迭代let done: boolean// 下一行内容let line: stringdo {  // 获得当前迭代器位置  let it=iter.next()  line = it.value  // 将读出的文本加入字符串  lines.push(line)  done = it.done} while (done)console.log('gxxt ',JSON.stringify(lines))

// 获取资源图片的字节数组let buffer=this.context.resourceManager.getMediaContentSync($r('app.media.startIcon')).buffer// 打开要写入的文件let file=fileIo.openSync(this.context.tempDir+'/starticon.png',fileIo.OpenMode.CREATE|fileIo.OpenMode.WRITE_ONLY)// 同步写入字节fileIo.writeSync(file.fd,buffer)// 关闭文件fileIo.close(file.fd)

// 要读取的文件let srcfile = fileIo.openSync(this.context.filesDir + '/zgl.jpg', fileIo.OpenMode.READ_WRITE)// 要写入的文件let destfile =  fileIo.openSync(this.context.cacheDir + '/zgl.jpg', fileIo.OpenMode.CREATE | fileIo.OpenMode.READ_WRITE)// 每次读入字节的个数let buffersize = 4069// 字节数组let buffer = new ArrayBuffer(buffersize)// 偏移量let off = 0// 每次真实读取的字节个数let len = 0// 总的字节个数let total = fileIo.statSync(srcfile.fd).size// 已经写入文件的字节个数let writetotal = 0// 每次都从srcfile中读取字节while (len = fileIo.readSync(srcfile.fd, buffer, { offset: off, length: buffersize })) {  // 下次要读取的时候 偏移量更新  off += len  // 将读出的字节写入文件  fileIo.writeSync(destfile.fd, buffer, { length: len })  // 更新一下已经写入的文件的字节个数  writetotal += len  // 要写入的字节个数已经不足字节数组的长度的时候  if (total - writetotal < buffersize) {    buffersize = total - writetotal  }}fileIo.closeSync(destfile.fd)