Data Storage
រក្សាទុកទិន្នន័យ
Android ផ្តល់វិធីជាច្រើនក្នុងការរក្សាទុកទិន្នន័យ។ ការជ្រើសរើសវិធី storage ត្រឹមត្រូវគឺសំខាន់ណាស់!
🗄️ Storage Hierarchy (Decision Tree)
Need to store data?
│
┌──────────────────┼──────────────────┐
▼ ▼ ▼
Simple data? Structured data? Large files?
(key-value) (tables) (images)
│ │ │
▼ ▼ ▼
SharedPreferences SQLite/Room Internal/External
DataStore Storage
📁 Storage Options Comparison
| Type | ពេលណាប្រើ | Size Limit | Speed |
|---|---|---|---|
| SharedPreferences | Settings, preferences, flags | < 1 MB | ⚡⚡⚡ Very Fast |
| Internal Storage | Private files, cache | Available space | ⚡⚡ Fast |
| External Storage | Large files, shared files | SD card size | ⚡ Medium |
| SQLite Database | Structured data, relationships | ~2 GB | ⚡⚡ Fast (indexed) |
| Room Database | Modern SQLite wrapper | ~2 GB | ⚡⚡⚡ Fast + Safe |
💾 SharedPreferences Deep Dive
SharedPreferences រក្សាទុកទិន្នន័យជា XML file នៅក្នុង /data/data/package_name/shared_prefs/
| Feature | Description |
|---|---|
| Storage Location | Internal storage (private) |
| Data Format | XML (key-value pairs) |
| Supported Types | String, int, long, float, boolean, Set |
| Thread Safety | ⚠️ Not thread-safe (use commit/apply correctly) |
| Performance | Fast for small data (< 1MB) |
🆕 DataStore (Modern Alternative)
DataStore គឺជា replacement ទំនើបសម្រាប់ SharedPreferences:
| Feature | SharedPreferences | DataStore |
|---|---|---|
| Thread Safety | ❌ Not safe | ✅ Fully safe |
| Async/Await | ❌ Blocking | ✅ Coroutines/Flow |
| Type Safety | ❌ Runtime errors | ✅ Compile-time safety |
| Data Loss | ⚠️ Possible (crashes) | ✅ Transactional |
| Recommendation | Legacy apps | ✅ New projects |
📂 Storage Locations
| Location | Path | Access |
|---|---|---|
| Internal Storage | /data/data/package_name/ |
🔒 Private (app only) |
| External Storage | /storage/emulated/0/ |
🌐 Public (all apps) |
| Cache | /data/data/package_name/cache/ |
🗑️ Temporary (auto-delete) |
🔐 Scoped Storage (Android 10+)
Android 10+ ដាក់ការកំណត់ access ទៅ external storage:
| Before Android 10 | Android 10+ |
|---|---|
| ✅ Direct file path access | ❌ No direct access |
| ❌ Security risks | ✅ Use MediaStore API |
| ❌ Permission required | ✅ No permission for own files |
💡 Best Practice: ប្រើ getFilesDir() for internal files និង MediaStore API សម្រាប់ shared files!
Java Code
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