From def5edbd270ee8f88c230b44d1d4cb7611b464a6 Mon Sep 17 00:00:00 2001
From: Patrick Strawderman <pstrawderman@netflix.com>
Date: Tue, 22 Apr 2025 16:53:38 -0500
Subject: [PATCH] Use HexFormat in ContentDisposition

Signed-off-by: Patrick Strawderman <pstrawderman@netflix.com>
---
 .../http/ContentDisposition.java              | 31 ++++++-------------
 1 file changed, 10 insertions(+), 21 deletions(-)

diff --git a/spring-web/src/main/java/org/springframework/http/ContentDisposition.java b/spring-web/src/main/java/org/springframework/http/ContentDisposition.java
index f60ba68801ee..10e15cd1a6cf 100644
--- a/spring-web/src/main/java/org/springframework/http/ContentDisposition.java
+++ b/spring-web/src/main/java/org/springframework/http/ContentDisposition.java
@@ -22,6 +22,7 @@
 import java.util.ArrayList;
 import java.util.Base64;
 import java.util.BitSet;
+import java.util.HexFormat;
 import java.util.List;
 import java.util.Locale;
 import java.util.regex.Matcher;
@@ -60,6 +61,8 @@ public final class ContentDisposition {
 
 	private static final BitSet PRINTABLE = new BitSet(256);
 
+	private static final HexFormat HEX_FORMAT = HexFormat.of().withUpperCase();
+
 
 	static {
 		// RFC 2045, Section 6.7, and RFC 2047, Section 4.2
@@ -385,9 +388,10 @@ private static String decodeRfc5987Filename(String filename, Charset charset) {
 				index++;
 			}
 			else if (b == '%' && index < value.length - 2) {
-				char[] array = new char[]{(char) value[index + 1], (char) value[index + 2]};
 				try {
-					baos.write(Integer.parseInt(String.valueOf(array), 16));
+					int high = HexFormat.fromHexDigit(value[index + 1]);
+					int low = HexFormat.fromHexDigit(value[index + 2]);
+					baos.write(high << 4 | low);
 				}
 				catch (NumberFormatException ex) {
 					throw new IllegalArgumentException(INVALID_HEADER_FIELD_PARAMETER_FORMAT, ex);
@@ -428,11 +432,8 @@ private static String decodeQuotedPrintableFilename(String filename, Charset cha
 				index++;
 			}
 			else if (b == '=' && index < value.length - 2) {
-				int i1 = Character.digit((char) value[index + 1], 16);
-				int i2 = Character.digit((char) value[index + 2], 16);
-				if (i1 == -1 || i2 == -1) {
-					throw new IllegalArgumentException("Not a valid hex sequence: " + filename.substring(index));
-				}
+				int i1 = HexFormat.fromHexDigit(value[index + 1]);
+				int i2 = HexFormat.fromHexDigit(value[index + 2]);
 				baos.write((i1 << 4) | i2);
 				index += 3;
 			}
@@ -469,10 +470,7 @@ else if (isPrintable(b)) {
 			}
 			else {
 				sb.append('=');
-				char ch1 = hexDigit(b >> 4);
-				char ch2 = hexDigit(b);
-				sb.append(ch1);
-				sb.append(ch2);
+				HEX_FORMAT.toHexDigits(sb, b);
 			}
 		}
 		sb.append("?=");
@@ -546,21 +544,12 @@ private static String encodeRfc5987Filename(String input, Charset charset) {
 			}
 			else {
 				sb.append('%');
-				char hex1 = hexDigit(b >> 4);
-				char hex2 = hexDigit(b);
-				sb.append(hex1);
-				sb.append(hex2);
+				HEX_FORMAT.toHexDigits(sb, b);
 			}
 		}
 		return sb.toString();
 	}
 
-	private static char hexDigit(int b) {
-		return Character.toUpperCase(Character.forDigit(b & 0xF, 16));
-	}
-
-
-
 	/**
 	 * A mutable builder for {@code ContentDisposition}.
 	 */