Reduce overhead of char[] creation

There are more locations which could benefit from not using a
toCharArray on a String, but rather use the charAt method from
the String itself. This to prevent an additional copy of the
char[] being created.

spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJAdviceParameterNameDiscoverer.java

@@ -475,8 +475,8 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		}
 		if (Character.isJavaIdentifierStart(candidateToken.charAt(0)) &&
 				Character.isLowerCase(candidateToken.charAt(0))) {
-			char[] tokenChars = candidateToken.toCharArray();
-			for (char tokenChar : tokenChars) {
+			for (int i = 1; i < candidateToken.length(); i++) {
+				char tokenChar = candidateToken.charAt(i);
 				if (!Character.isJavaIdentifierPart(tokenChar)) {
 					return null;
 				}

spring-core/src/main/java/org/springframework/core/Conventions.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -225,11 +225,11 @@ public final class Conventions {
 		if (!attributeName.contains("-")) {
 			return attributeName;
 		}
-		char[] chars = attributeName.toCharArray();
-		char[] result = new char[chars.length -1]; // not completely accurate but good guess
+		char[] result = new char[attributeName.length() -1]; // not completely accurate but good guess
 		int currPos = 0;
 		boolean upperCaseNext = false;
-		for (char c : chars) {
+		for (int i = 0; i < attributeName.length(); i++ ) {
+			char c = attributeName.charAt(i);
 			if (c == '-') {
 				upperCaseNext = true;
 			}

spring-web/src/main/java/org/springframework/http/ContentDisposition.java

@@ -485,7 +485,8 @@ public final class ContentDisposition {
 		}
 		boolean escaped = false;
 		StringBuilder sb = new StringBuilder();
-		for (char c : filename.toCharArray()) {
+		for (int i = 0; i < filename.length() ; i++) {
+			char c = filename.charAt(i);
 			if (!escaped && c == '"') {
 				sb.append("\\\"");
 			}

spring-web/src/main/java/org/springframework/http/ResponseCookie.java

@@ -386,9 +386,8 @@ public final class ResponseCookie extends HttpCookie {
 				start = 1;
 				end--;
 			}
-			char[] chars = value.toCharArray();
 			for (int i = start; i < end; i++) {
-				char c = chars[i];
+				char c = value.charAt(i);
 				if (c < 0x21 || c == 0x22 || c == 0x2c || c == 0x3b || c == 0x5c || c == 0x7f) {
 					throw new IllegalArgumentException(
 							"RFC2616 cookie value cannot have '" + c + "'");

spring-web/src/main/java/org/springframework/http/server/DefaultPathContainer.java

@@ -232,8 +232,6 @@ final class DefaultPathContainer implements PathContainer {
 
 		private final String valueToMatch;
 
-		private final char[] valueToMatchAsChars;
-
 		private final MultiValueMap<String, String> parameters;
 
 
@@ -243,7 +241,6 @@ final class DefaultPathContainer implements PathContainer {
 		DefaultPathSegment(String value, String valueToMatch, MultiValueMap<String, String> params) {
 			this.value = value;
 			this.valueToMatch = valueToMatch;
-			this.valueToMatchAsChars = valueToMatch.toCharArray();
 			this.parameters = CollectionUtils.unmodifiableMultiValueMap(params);
 		}
 
@@ -254,7 +251,6 @@ final class DefaultPathContainer implements PathContainer {
 			this.value = value;
 			this.valueToMatch = value.contains(separator.encodedSequence()) ?
 					value.replaceAll(separator.encodedSequence(), separator.value()) : value;
-			this.valueToMatchAsChars = this.valueToMatch.toCharArray();
 			this.parameters = EMPTY_PARAMS;
 		}
 
@@ -271,7 +267,7 @@ final class DefaultPathContainer implements PathContainer {
 
 		@Override
 		public char[] valueToMatchAsChars() {
-			return this.valueToMatchAsChars;
+			return this.valueToMatch.toCharArray();
 		}
 
 		@Override

spring-web/src/main/java/org/springframework/web/util/HierarchicalUriComponents.java

@@ -791,7 +791,8 @@ final class HierarchicalUriComponents extends UriComponents {
 			clear(this.currentLiteral);
 			clear(this.currentVariable);
 			clear(this.output);
-			for (char c : source.toCharArray()) {
+			for (int i = 0; i < source.length(); i++) {
+				char c = source.charAt(i);
 				if (c == '{') {
 					level++;
 					if (level == 1) {

spring-web/src/main/java/org/springframework/web/util/UriComponents.java

@@ -278,7 +278,8 @@ public abstract class UriComponents implements Serializable {
 		int level = 0;
 		int lastCharIndex = 0;
 		char[] chars = new char[source.length()];
-		for (char c : source.toCharArray()) {
+		for (int i = 0; i < source.length(); i++) {
+			char c = source.charAt(i);
 			if (c == '{') {
 				level++;
 			}

spring-web/src/main/java/org/springframework/web/util/pattern/LiteralPathElement.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -69,10 +69,9 @@ class LiteralPathElement extends PathElement {
 			return false;
 		}
 
-		char[] data = ((PathContainer.PathSegment)element).valueToMatchAsChars();
 		if (this.caseSensitive) {
 			for (int i = 0; i < this.len; i++) {
-				if (data[i] != this.text[i]) {
+				if (value.charAt(i) != this.text[i]) {
 					return false;
 				}
 			}
@@ -80,7 +79,7 @@ class LiteralPathElement extends PathElement {
 		else {
 			for (int i = 0; i < this.len; i++) {
 				// TODO revisit performance if doing a lot of case insensitive matching
-				if (Character.toLowerCase(data[i]) != this.text[i]) {
+				if (Character.toLowerCase(value.charAt(i)) != this.text[i]) {
 					return false;
 				}
 			}

spring-web/src/main/java/org/springframework/web/util/pattern/SingleCharWildcardedPathElement.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -74,11 +74,10 @@ class SingleCharWildcardedPathElement extends PathElement {
 			return false;
 		}
 
-		char[] data = ((PathSegment)element).valueToMatchAsChars();
 		if (this.caseSensitive) {
 			for (int i = 0; i < this.len; i++) {
 				char ch = this.text[i];
-				if ((ch != '?') && (ch != data[i])) {
+				if ((ch != '?') && (ch != value.charAt((i)))) {
 					return false;
 				}
 			}
@@ -87,7 +86,7 @@ class SingleCharWildcardedPathElement extends PathElement {
 			for (int i = 0; i < this.len; i++) {
 				char ch = this.text[i];
 				// TODO revisit performance if doing a lot of case insensitive matching
-				if ((ch != '?') && (ch != Character.toLowerCase(data[i]))) {
+				if ((ch != '?') && (ch != Character.toLowerCase(value.charAt(i)))) {
 					return false;
 				}
 			}