【Harmony OS】【ARK UI】ets实现文件读写操作

1. 准备阶段

关于该功能的实现我们需要学习以下的资料：

1.1 【ARKUI】ets怎么实现文件操作

1.2 文件管理

1.3 Ability上下文

2. demo 实现

2.1 文件路径读取

参考 context.getFilesDir 来进行获取文件路径，代码如下

private getCacheDir(){
    var context = ability_featureAbility.getContext();
    context.getFilesDir()
      .then((data) => {
        console.log('File directory obtained. Data:' + data);
        this.path=data;
      }).catch((error) => {
      console.error('Failed to obtain the file directory. Cause: ' + error.message);
    })
}

2.2 文件写入操作

参考 fileio.createStream 和 write 和 flush 相关 Api，资料和代码如下

实现代码

private writeFile(){
    let ss= fileio.createStreamSync(this.path+"/111.txt", "w+");
    let num =  ss.write("你好 2022",null);
    ss.flush();
    console.log("写入成功");
}

2.3 文件读取文件操作

想实现文件的读取，需要参考 read 的 Api，资料和代码如下：

代码如下：

private readFile(){
    let ss = fileio.createStreamSync(this.path+"/111.txt", "r+");
    ss.read(new ArrayBuffer(4096),null,function (err, readOut) {
      if (!err) {
        let  encodedString = String.fromCodePoint.apply(null, new Uint8Array(readOut.buffer));
        let decodedString = decodeURIComponent(escape(encodedString));//没有这一步中文会乱码
        console.log("读取文件内容："+decodedString);
      }
  });
}

3. 运行效果

3.1 全部代码如下

import fileio from '@ohos.fileio';
import ability_featureAbility from '@ohos.ability.featureAbility';
@Entry
@Component
struct MyFileStream {
  @State path:string="";
  private getFilesDirNew(){
    var context = ability_featureAbility.getContext();
    context.getFilesDir()
      .then((data) => {
        console.log('获取文件路径成功' + data);
        this.path=data;
      }).catch((error) => {
      console.error('Failed to obtain the file directory. Cause: ' + error.message);
    })
  }

  private writeFile(){
    let ss= fileio.createStreamSync(this.path+"/111.txt", "w+");
    let num =  ss.write("你好 2022",null);
    ss.flush();
    console.log("写入成功")
  }

  private readFile(){
    let ss = fileio.createStreamSync(this.path+"/111.txt", "r+");
    ss.read(new ArrayBuffer(4096),null,function (err, readOut) {
      if (!err) {
        let  encodedString = String.fromCodePoint.apply(null, new Uint8Array(readOut.buffer));
        let decodedString = decodeURIComponent(escape(encodedString));//没有这一步中文会乱码
        console.log("读取文件内容："+decodedString);
      }
    });
  }

  build() {
    Flex({ direction: FlexDirection.Column, alignItems: ItemAlign.Center, justifyContent: FlexAlign.Center }) {

      Text('获取文件路径')
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .backgroundColor(Color.Red)
      .onClick(this.getFilesDirNew.bind(this))
      Text('写入文字')
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .backgroundColor(Color.White)
      .onClick(this.writeFile.bind(this))
      Text('读取文字')
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .backgroundColor(Color.Red)
      .onClick(this.readFile.bind(this))
    }
    .width('100%')
    .height('100%')
  }
}

3.2 运行效果如下