Hongmeng Next's Core File Kit uses "sandbox isolation + minimalist interface" to achieve safe and efficient file management.This article uses streamlined language to analyze core functions and practical points~
1. Core capabilities: "Swiss Army Knife" for file operation🔪
Core File Kit is a lightweight file management tool provided by Hongmeng, focusing on in-app file lifecycle management, and supports:
Basic operations: Create/read/write/delete files, traverse directories
Security mechanism: Sandbox isolation (independent storage space)
Scenario adaptation: Configure storage, user data, cache management
2. Core interface quick lookup table🚀
| Operation Type | Key Interface | Sample Code |
|---|---|---|
| Open/Create file | File.open(path, mode) | const fd = File.open('/data/file.txt', File.MODE_CREATE); |
| Write data | File.write(fd, data) | File.write(fd, 'Hello HarmonyOS!'); |
| Read data | File.read(fd, buffer) | const buffer = new ArrayBuffer(1024); File.read(fd, buffer); |
| Delete File | File.delete(path) | File.delete('/data/file.txt'); |
| Check the file exists | File.exists(path) | if (File.exists('/data/cache')) { ... } |
3. Practical combat: Example of the entire process of file operation📝
CODE
import { File } from '@kit.CoreFileKit';
const FILE_PATH = '/data/storage/el2/files/config.txt';
async function fileOpsDemo() {
try {
// 1. Open the file (create if it does not exist, read and write mode)
const fd = File.open(FILE_PATH, File.MODE_READ_WRITE | File.MODE_CREATE);
// 2. Write configuration data
const configData = JSON.stringify({ theme: 'dark', fontSize: 16 });
File.write(fd, configData);
console.log('Configuration write successful');
// 3. Read data and parse
const buffer = new Uint8Array(1024);
const bytesRead = File.read(fd, buffer);
const content = new TextDecoder().decode(buffer.subarray(0, bytesRead));
const config = JSON.parse(content);
console.log('Current configuration:', config);
// 4. Clean cached files
File.delete('/data/cache/temp.log');
console.log('Cache Cleanup Completed');
} catch (error) {
console.error('File operation failed:', error);
}
}
4. Sandbox isolation: the "moat" of data security 🏰
1. Storage structure
CODE
Application Sandbox Directory (Example)
├─ files/ # Permanent storage (user data, uninstalled and deleted with the application)
│ └─ config.txt
├─ cache/ # Temporary cache (the system can be automatically cleaned)
│ └─ temp.jpg
└─ databases/ # database files (managed by ArkUI X)
2. Safety features
Isolation: Other applications cannot access the sandbox path of this application
Permission Control: Only the application itself can read and write files in the sandbox
Automatic cleaning:cache/directory file can be automatically deleted by the system according to memory conditions
3. Best Practices
CODE
// Recommended: Use the system-provided sandbox path API
import { FileManager } from '@ohos.file.fileManager';
// Get the application private directory (automatically process sandbox path)
const appFilesDir = FileManager.getAppFilesDir();
const safePath = `${appFilesDir}/user_data.json`;
5. Performance optimization: Make the operation more "lightweight" ⚡
1. Streaming reading and writing (large file scenario)
CODE
// Read large files in chunks (avoid memory overflow)
const CHUNK_SIZE = 4096;
const fd = File.open('/data/video.mp4', File.MODE_READ);
const stream = new FileStream(fd, CHUNK_SIZE);
while (await stream.readChunk(buffer)) {
processChunk(buffer); // Process chunked data
}
2. Cache Policy
CODE
// Automatically clean cached files from 7 days ago
function cleanOldCache() {
const cacheDir = FileManager.getAppCacheDir();
const files = File.list(cacheDir);
files.forEach(file => {
const mtime = File.stat(file).mtime;
if (Date.now() - mtime > 7 * 24 * 3600 * 1000) {
File.delete(file);
}
});
}
Summary: 3 steps to master the core usage
Path Management: UseFileManager.getAppFilesDir()to obtain a secure path
Operation process: open → write/read → close (or delete)
Safety principle: Sensitive data is stored infiles/, and temporary data iscache/
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