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⚡ Bolt: 성능 최적화 - HexFormat을 사용한 헥스 문자열 변환 속도 개선 #67

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⚡ Bolt: 성능 최적화 - HexFormat을 사용한 헥스 문자열 변환 속도 개선 #67

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3 changes: 3 additions & 0 deletions .jules/bolt.md
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Original file line number Diff line number Diff line change
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## 2026-07-01 - Byte Array to Hex String Conversion Optimization
**Learning:** In Java 21, using `String.format("%02x", b)` inside a loop to convert a byte array to a hex string causes unnecessary allocations and is significantly slower than native alternatives.
**Action:** Use `java.util.HexFormat.of().formatHex(bytes)` for faster and allocation-free conversions from byte arrays to hex strings in this codebase.
8 changes: 3 additions & 5 deletions src/main/java/com/clearfolio/viewer/service/DefaultDocumentConversionService.java
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Expand Up @@ -121,12 +121,10 @@ private String contentHash(MultipartFile file) {
}

byte[] raw = digest.digest();
StringBuilder hex = new StringBuilder(raw.length * 2);
for (byte b : raw) {
hex.append(String.format("%02x", b));
}

return hex.toString();
// Bolt Performance Optimization:
// Use HexFormat instead of String.format loop for performance.
return java.util.HexFormat.of().formatHex(raw);
} catch (NoSuchAlgorithmException ex) {
throw new IllegalStateException("SHA-256 digest unavailable", ex);
} catch (IOException ex) {
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