HarmonyOS Next Application File Space Statistics and Management

This article aims to deeply explore the technical details of file management in the Huawei HarmonyOS Next system (up to API 12 as of now), and is summarized based on actual development practices.
It mainly serves as a carrier for technical sharing and communication. Mistakes and omissions are inevitable. Colleagues are welcome to put forward valuable opinions and questions so that we can make progress together.
This article is original content, and any form of reprint must indicate the source and the original author.

Introduction
In mobile application development, storage space management is a crucial part. Reasonable allocation and management of storage space can not only ensure the smooth operation of the application but also improve the user experience. HarmonyOS Next provides us developers with comprehensive file space statistics and management interfaces, helping us to deeply understand the usage of application and system storage space and conduct efficient space management.
1. Importance of File Space Statistics

• Performance Optimization: By analyzing the application storage space usage, developers can identify and optimize the parts of the application that occupy a large amount of space, reduce redundant data, and improve the application's running efficiency.
• Avoiding Insufficient Space: Timely understanding of the system storage space situation can avoid problems such as application crashes, data loss, or slow system operation caused by insufficient space.
• Enhancing User Experience: Reasonable management of application file space, avoiding the application from occupying too much storage space and affecting the use of other applications by users, improves the user experience. 2. Space Statistics Interfaces and Functions HarmonyOS Next provides the following interfaces for statistics of application and system storage space:
• @ohos.file.statvfs: Obtains the space information of the specified file system, including total space, free space, number of file nodes, etc.
• @ohos.file.storageStatistics: Obtains the storage space information of the current application, including the size of the application installation file, cache file size, data file size, etc. 3. Sample Code: Implementation of Space Statistics The following sample code shows how to use the above interfaces to obtain the application and system storage space information: Obtaining the Application Installation File Size

import { storageStatistics } from '@kit.CoreFileKit';
storageStatistics.getCurrentBundleStats((err, bundleStats) => {
  if (err) {
    console.error('Failed to get bundle stats:', err);
  } else {
    console.log('App installation size:', bundleStats.appSize);
  }
});

Obtaining the Free Space of the Specified File System

import { statfs } from '@kit.CoreFileKit';
let context = getContext(this) as common.UIAbilityContext;
let path = context.filesDir;
statfs.getFreeSize(path, (err, number) => {
  if (err) {
    console.error('Failed to get free size:', err);
  } else {
    console.log('Free size:', number);
  }
});

4. Optimization Suggestions for Application Space Management

• Cache File Management:
  • Regular Cleaning: Regularly clean the application cache files to release storage space. For example, you can use a timer task or listen to system events (such as a low memory warning) to trigger cache cleaning.
  • Hierarchical Storage: According to the file access frequency, store the cache files hierarchically. For example, store the most frequently accessed files in memory or SSD, and store the less frequently accessed files in HDD.
• Database Optimization:
  • Index Optimization: Add appropriate indexes to the database tables to improve the data query efficiency, reduce the data reading time, and reduce the storage space occupation.
  • Data Compression: For the data stored in the database, you can use data compression technologies such as zlib and Snappy to reduce the data space occupation.
• File Storage Optimization:
  • File Compression: For compressible files such as pictures and videos, you can use file compression technologies such as zip and gzip to reduce the file space occupation.
  • File Segmentation: For large files, you can use file segmentation technology to divide the file into multiple small files and store them separately to improve the file read and write efficiency.
• Storage Space Monitoring:
  • Regular Monitoring: Regularly monitor the usage of application and system storage space, timely detect the problem of insufficient space, and handle it.
  • Early Warning Mechanism: Set up a storage space early warning mechanism. When the storage space reaches a certain threshold, timely notify the user or trigger a cleaning operation. 5. Conclusion HarmonyOS Next provides rich file space statistics and management interfaces, helping us developers to deeply understand the usage of application and system storage space and conduct efficient space management. We can manage the application file space reasonably by optimizing the application design, cleaning cache files, using databases, using compression technologies, etc., improve the application performance, enhance the user experience, and create better-quality applications.