鸿蒙关于手机全局本地文件读取，写入

一.背景

需求是需要操作用户手机中的文件，不是应用沙箱

二.解决方案

这里要注意的一点拿到fsOpen.path的路径再去进行open文件，因为这里还不知道本地文件路径在哪里，需要选择一下路径再拿到路径去请求

1.这里就是进行两个fs.open，拿到你需要操作的文件的路径以后第一个就没用了,如果是需要新建文件也可以省去这步

const DocumentSelectOptions = new picker.DocumentSelectOptions();
      let context = getContext(this) as common.Context;
      // 创建文件选择器实例。
      const documentViewPicker = new picker.DocumentViewPicker(context);
      documentViewPicker.select(DocumentSelectOptions)
        .then(async (documentSelectResult) => {
          // 获取选择路径
          let uri = documentSelectResult[0];
          console.log('e2qdw',uri)
          // 若文件不存在则创建文件
          //const fsOpen = await fs.open(uri,fs.OpenMode.READ_WRITE | fs.OpenMode.READ_ONLY |fs.OpenMode.CREATE)
          //console.log(fsOpen.path)
  const fsOpen = await fs.open(这里的路径就是fsOpen.path,fs.OpenMode.READ_WRITE | fs.OpenMode.READ_ONLY |fs.OpenMode.CREATE)
          // 读取文件
          this.readFile(fsOpen)
          // 写入
          this.writeFile(fsOpen)
        })
        .catch((err:BusinessError) => {
          console.error(`Invoke documentPicker.select failed, code is ${err.code}, message is ${err.message}`);
        })

2.第一步拿到以后就可以替换成这个代码 ，找到需要操作文件的路径，DocumentSelectOptions文件选择器就没用了

 async getFiles() {
    try {
      // 若文件不存在则创建文件
      // OpenMode.CREATE若文件不存在，则创建文件。
      //OpenMode.TRUNC如果文件存在且文件具有写权限，则将其长度裁剪为零。覆盖  不是追加
      const fsOpen = await fs.open('/storage/Users/currentUser/Download/jrdl.json',fs.OpenMode.READ_WRITE | fs.OpenMode.READ_ONLY |fs.OpenMode.CREATE|fs.OpenMode.TRUNC)
      // // 读取文件
      this.readFile(fsOpen)
      // this.deleteFile(fsOpen)
      // 写入
      this.writeFile(fsOpen)

    } catch (e) {
      console.error(`Invoke documentViewPicker.save failed, code is ${e.code}, message is ${e.message}`);
    }
  }

3.读写文件代码

readFile(fsOpen:fs.File){
    // 读取文件
    let arrayBuffer = new ArrayBuffer(4096);
    fs.read(fsOpen.fd, arrayBuffer, (err: BusinessError, readLen: number) => {
      if (err) {
        console.error("read failed with error message: " + err.message + ", error code: " + err.code);
      } else {
        console.info("read file data succeed");
        let buf = buffer.from(arrayBuffer, 0, readLen);
        console.info(`成功读取文件内容: ${buf.toString()}`);
      }
      // fs.closeSync(fsOpen);
    });
  }
  writeFile(fsOpen:fs.File){
    let str: string = "hello,word";
    fs.write(fsOpen.fd, str, (err: BusinessError, writeLen: number) => {
      if (err) {
        console.error("write data to file failed with error message:" + err.message + ", error code: " + err.code);
      } else {
        promptAction.showToast({ message: '成功写入',duration:2000,alignment:Alignment.Center })
        console.info("成功写入大小为:" + writeLen);
      }
      fs.closeSync(fsOpen);
    });
  }

4.完整代码

封装成工具类了这里已经，直接拿着就能用

import { BusinessError } from '@kit.BasicServicesKit';
import fs, { ReadOptions, WriteOptions } from '@ohos.file.fs'; // 导入文件管理模块
import { buffer } from '@kit.ArkTS';
import { promptAction } from '@kit.ArkUI';
import { picker } from '@kit.CoreFileKit';
import { common } from '@kit.AbilityKit';

//执行UDP通讯的对象
export class fileUtils {
  async getFiles() {
    try {
      // 若文件不存在则创建文件
      const fsOpen = await fs.open('/storage/Users/currentUser/Download/jrdl.json',fs.OpenMode.READ_WRITE | fs.OpenMode.READ_ONLY |fs.OpenMode.CREATE|fs.OpenMode.TRUNC)
      // // 读取文件
      this.readFile(fsOpen)
      // this.deleteFile(fsOpen)
      // 写入
      this.writeFile(fsOpen)

    } catch (e) {
      console.error(`Invoke documentViewPicker.save failed, code is ${e.code}, message is ${e.message}`);
    }
  }

  readFile(fsOpen:fs.File){
    // 读取文件
    let arrayBuffer = new ArrayBuffer(4096);
    fs.read(fsOpen.fd, arrayBuffer, (err: BusinessError, readLen: number) => {
      if (err) {
        console.error("read failed with error message: " + err.message + ", error code: " + err.code);
      } else {
        console.info("read file data succeed");
        let buf = buffer.from(arrayBuffer, 0, readLen);
        console.info(`成功读取文件内容: ${buf.toString()}`);
      }
      // fs.closeSync(fsOpen);
    });
  }
  writeFile(fsOpen:fs.File){
    let str: string = "hello,word";
    fs.write(fsOpen.fd, str, (err: BusinessError, writeLen: number) => {
      if (err) {
        console.error("write data to file failed with error message:" + err.message + ", error code: " + err.code);
      } else {
        promptAction.showToast({ message: '成功写入',duration:2000,alignment:Alignment.Center })
        console.info("成功写入大小为:" + writeLen);
      }
      fs.closeSync(fsOpen);
    });
  }
  deleteFile(){
    fs.unlink('/storage/Users/currentUser/Download/jrdl.json').then(() => {
      console.info("remove file succeed");
    }).catch((err: BusinessError) => {
      console.error("remove file failed with error message: " + err.message + ", error code: " + err.code);
    });
  }
}

5.调用

  new fileUtils().getFiles()