HarmonyOS 如何使用app本地数据缓存以及清理缓存

仅使用可以参考APPStorage localStorage. set get方法

查询缓存用storageStatistics.getCurrentBundleStats()接口，可以获取缓存空间大小。

清除文件缓存：

查询缓存用storageStatistics.getCurrentBundleStats()接口，清除文件缓存，需要调用context的cacheDir获取缓存，然后调用系统文件fs接口，判断是文件或者文件夹，再分别消除缓存。

参考文档：

应用空间统计：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-file-storage-statistics-V5

文件管理：

https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-fileio-V5

demo如下：

import { storageStatistics } from '@kit.CoreFileKit';
import fs from '@ohos.file.fs';
import { Context } from '@kit.AbilityKit';
import { BusinessError } from '@ohos.base';

@Entry
@Component
struct Index {
  @State message: string = 'Hello World';

  //获取缓存
  getCacheSize() {
    storageStatistics.getCurrentBundleStats((error: BusinessError, bundleStats: storageStatistics.BundleStats) => {
      if (error) {
        console.error("getCurrentBundleStats failed with error:" + JSON.stringify(error));
      } else {
        let cacheSize = parseFloat((bundleStats.cacheSize / (1024*1024)).toFixed(1))
        console.info('cacheSize:' + cacheSize);
      }
    })
  }

  //清理缓存
  clearCache() {
    const context: Context = getContext(this);
    let cacheDir = context.cacheDir
    fs.listFile(cacheDir).then((filenames) => {
      for (let i = 0;i < filenames.length; i++) {
        let dirPath = cacheDir+filenames[i]
        try {
          // 判断是否文件夹
          let isDirectory = fs.statSync(dirPath).isDirectory()
          if (isDirectory) {
            fs.rmdirSync(dirPath)
          } else {
            fs.unlink(dirPath).then(() => {
              console.info('remove file succeed');
            }).catch((err: BusinessError) => {
              console.info("remove file failed with error message: " + err.message + ", error code: " + err.code);
            });
          }
        }catch (e) {
          console.log(e)
        }
      }
    })
  }

  build() {
    Column() {
      Text(this.message)
        .id('JSONParseModelPageHelloWorld')
        .fontSize(50)
        .fontWeight(FontWeight.Bold)
        .alignRules({
          center: { anchor: '__container__', align: VerticalAlign.Center },
          middle: { anchor: '__container__', align: HorizontalAlign.Center }
        })
    }
    .height('100%')
    .width('100%')
  }
}