Use Locale.ROOT for locale neutral, case insensitive comparisons

spring-beans/src/main/java/org/springframework/beans/support/PropertyComparator.java

@@ -19,6 +19,7 @@
 import java.util.Arrays;
 import java.util.Comparator;
 import java.util.List;
+import java.util.Locale;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -77,8 +78,8 @@ public int compare(T o1, T o2) {
 		Object v1 = getPropertyValue(o1);
 		Object v2 = getPropertyValue(o2);
 		if (this.sortDefinition.isIgnoreCase() && (v1 instanceof String) && (v2 instanceof String)) {
-			v1 = ((String) v1).toLowerCase();
-			v2 = ((String) v2).toLowerCase();
+			v1 = ((String) v1).toLowerCase(Locale.ROOT);
+			v2 = ((String) v2).toLowerCase(Locale.ROOT);
 		}
 
 		int result;

spring-context-support/src/main/java/org/springframework/scheduling/quartz/LocalDataSourceJobStore.java

@@ -19,6 +19,7 @@
 import java.sql.Connection;
 import java.sql.DatabaseMetaData;
 import java.sql.SQLException;
+import java.util.Locale;
 
 import javax.sql.DataSource;
 
@@ -155,7 +156,7 @@ public void initialize() {
 			String productName = JdbcUtils.extractDatabaseMetaData(this.dataSource,
 					DatabaseMetaData::getDatabaseProductName);
 			productName = JdbcUtils.commonDatabaseName(productName);
-			if (productName != null && productName.toLowerCase().contains("hsql")) {
+			if (productName != null && productName.toLowerCase(Locale.ROOT).contains("hsql")) {
 				setUseDBLocks(false);
 				setLockHandler(new SimpleSemaphore());
 			}

spring-context/src/main/java/org/springframework/format/datetime/standard/MonthFormatter.java

@@ -34,7 +34,7 @@ class MonthFormatter implements Formatter<Month> {
 
 	@Override
 	public Month parse(String text, Locale locale) throws ParseException {
-		return Month.valueOf(text.toUpperCase());
+		return Month.valueOf(text.toUpperCase(Locale.ROOT));
 	}
 
 	@Override

spring-context/src/main/java/org/springframework/scheduling/support/CronField.java

@@ -21,6 +21,7 @@
 import java.time.temporal.ChronoUnit;
 import java.time.temporal.Temporal;
 import java.time.temporal.ValueRange;
+import java.util.Locale;
 import java.util.function.BiFunction;
 
 import org.springframework.lang.Nullable;
@@ -143,7 +144,7 @@ private static CronField parseList(String value, Type type, BiFunction<String, T
 	}
 
 	private static String replaceOrdinals(String value, String[] list) {
-		value = value.toUpperCase();
+		value = value.toUpperCase(Locale.ROOT);
 		for (int i = 0; i < list.length; i++) {
 			String replacement = Integer.toString(i + 1);
 			value = StringUtils.replace(value, list[i], replacement);

spring-context/src/main/java/org/springframework/scheduling/support/CronSequenceGenerator.java

@@ -23,6 +23,7 @@
 import java.util.Date;
 import java.util.GregorianCalendar;
 import java.util.List;
+import java.util.Locale;
 import java.util.TimeZone;
 
 import org.springframework.lang.Nullable;
@@ -305,8 +306,8 @@ private void doParse(String[] fields) {
 	private String replaceOrdinals(String value, String commaSeparatedList) {
 		String[] list = StringUtils.commaDelimitedListToStringArray(commaSeparatedList);
 		for (int i = 0; i < list.length; i++) {
-			String item = list[i].toUpperCase();
-			value = StringUtils.replace(value.toUpperCase(), item, "" + i);
+			String item = list[i].toUpperCase(Locale.ROOT);
+			value = StringUtils.replace(value.toUpperCase(Locale.ROOT), item, "" + i);
 		}
 		return value;
 	}

spring-context/src/main/java/org/springframework/validation/DataBinder.java

@@ -23,6 +23,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 
 import org.apache.commons.logging.Log;
@@ -482,7 +483,8 @@ public void setDisallowedFields(@Nullable String... disallowedFields) {
 		else {
 			String[] fieldPatterns = new String[disallowedFields.length];
 			for (int i = 0; i < fieldPatterns.length; i++) {
-				fieldPatterns[i] = PropertyAccessorUtils.canonicalPropertyName(disallowedFields[i]).toLowerCase();
+				String field = PropertyAccessorUtils.canonicalPropertyName(disallowedFields[i]);
+				fieldPatterns[i] = field.toLowerCase(Locale.ROOT);
 			}
 			this.disallowedFields = fieldPatterns;
 		}
@@ -825,7 +827,7 @@ protected boolean isAllowed(String field) {
 		String[] allowed = getAllowedFields();
 		String[] disallowed = getDisallowedFields();
 		return ((ObjectUtils.isEmpty(allowed) || PatternMatchUtils.simpleMatch(allowed, field)) &&
-				(ObjectUtils.isEmpty(disallowed) || !PatternMatchUtils.simpleMatch(disallowed, field.toLowerCase())));
+				(ObjectUtils.isEmpty(disallowed) || !PatternMatchUtils.simpleMatch(disallowed, field.toLowerCase(Locale.ROOT))));
 	}
 
 	/**

spring-core/src/main/java/org/springframework/core/convert/support/StringToBooleanConverter.java

@@ -17,6 +17,7 @@
 package org.springframework.core.convert.support;
 
 import java.util.HashSet;
+import java.util.Locale;
 import java.util.Set;
 
 import org.springframework.core.convert.converter.Converter;
@@ -55,7 +56,7 @@ public Boolean convert(String source) {
 		if (value.isEmpty()) {
 			return null;
 		}
-		value = value.toLowerCase();
+		value = value.toLowerCase(Locale.ROOT);
 		if (trueValues.contains(value)) {
 			return Boolean.TRUE;
 		}

spring-core/src/main/java/org/springframework/core/env/SystemEnvironmentPropertySource.java

@@ -16,6 +16,7 @@
 
 package org.springframework.core.env;
 
+import java.util.Locale;
 import java.util.Map;
 
 import org.springframework.lang.Nullable;
@@ -109,7 +110,7 @@ protected final String resolvePropertyName(String name) {
 		if (resolvedName != null) {
 			return resolvedName;
 		}
-		String uppercasedName = name.toUpperCase();
+		String uppercasedName = name.toUpperCase(Locale.ROOT);
 		if (!name.equals(uppercasedName)) {
 			resolvedName = checkPropertyName(uppercasedName);
 			if (resolvedName != null) {

spring-core/src/main/java/org/springframework/util/MimeType.java

@@ -182,10 +182,10 @@ public MimeType(String type, String subtype, @Nullable Map<String, String> param
 		Assert.hasLength(subtype, "'subtype' must not be empty");
 		checkToken(type);
 		checkToken(subtype);
-		this.type = type.toLowerCase(Locale.ENGLISH);
-		this.subtype = subtype.toLowerCase(Locale.ENGLISH);
+		this.type = type.toLowerCase(Locale.ROOT);
+		this.subtype = subtype.toLowerCase(Locale.ROOT);
 		if (!CollectionUtils.isEmpty(parameters)) {
-			Map<String, String> map = new LinkedCaseInsensitiveMap<>(parameters.size(), Locale.ENGLISH);
+			Map<String, String> map = new LinkedCaseInsensitiveMap<>(parameters.size(), Locale.ROOT);
 			parameters.forEach((parameter, value) -> {
 				checkParameters(parameter, value);
 				map.put(parameter, value);

spring-core/src/main/java/org/springframework/util/ResourceUtils.java

@@ -23,6 +23,7 @@
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.net.URLConnection;
+import java.util.Locale;
 
 import org.springframework.lang.Nullable;
 
@@ -295,7 +296,7 @@ public static boolean isJarURL(URL url) {
 	 */
 	public static boolean isJarFileURL(URL url) {
 		return (URL_PROTOCOL_FILE.equals(url.getProtocol()) &&
-				url.getPath().toLowerCase().endsWith(JAR_FILE_EXTENSION));
+				url.getPath().toLowerCase(Locale.ROOT).endsWith(JAR_FILE_EXTENSION));
 	}
 
 	/**

spring-expression/src/main/java/org/springframework/expression/spel/SpelParserConfiguration.java

@@ -16,6 +16,8 @@
 
 package org.springframework.expression.spel;
 
+import java.util.Locale;
+
 import org.springframework.core.SpringProperties;
 import org.springframework.lang.Nullable;
 
@@ -45,7 +47,7 @@ public class SpelParserConfiguration {
 	static {
 		String compilerMode = SpringProperties.getProperty(SPRING_EXPRESSION_COMPILER_MODE_PROPERTY_NAME);
 		defaultCompilerMode = (compilerMode != null ?
-				SpelCompilerMode.valueOf(compilerMode.toUpperCase()) : SpelCompilerMode.OFF);
+				SpelCompilerMode.valueOf(compilerMode.toUpperCase(Locale.ROOT)) : SpelCompilerMode.OFF);
 	}
 
 

spring-expression/src/main/java/org/springframework/expression/spel/ast/TypeReference.java

@@ -17,6 +17,7 @@
 package org.springframework.expression.spel.ast;
 
 import java.lang.reflect.Array;
+import java.util.Locale;
 
 import org.springframework.asm.MethodVisitor;
 import org.springframework.asm.Type;
@@ -57,7 +58,7 @@ public TypedValue getValueInternal(ExpressionState state) throws EvaluationExcep
 		String typeName = (String) this.children[0].getValueInternal(state).getValue();
 		Assert.state(typeName != null, "No type name");
 		if (!typeName.contains(".") && Character.isLowerCase(typeName.charAt(0))) {
-			TypeCode tc = TypeCode.valueOf(typeName.toUpperCase());
+			TypeCode tc = TypeCode.valueOf(typeName.toUpperCase(Locale.ROOT));
 			if (tc != TypeCode.OBJECT) {
 				// It is a primitive type
 				Class<?> clazz = makeArrayIfNecessary(tc.getType());

spring-expression/src/main/java/org/springframework/expression/spel/standard/InternalSpelExpressionParser.java

@@ -21,6 +21,7 @@
 import java.util.Collections;
 import java.util.Deque;
 import java.util.List;
+import java.util.Locale;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 import java.util.regex.Pattern;
@@ -750,7 +751,7 @@ private SpelNodeImpl eatPossiblyQualifiedId() {
 				throw internalException( this.expressionString.length(), SpelMessage.OOD);
 			}
 			throw internalException(node.startPos, SpelMessage.NOT_EXPECTED_TOKEN,
-					"qualified ID", node.getKind().toString().toLowerCase());
+					"qualified ID", node.getKind().toString().toLowerCase(Locale.ROOT));
 		}
 		return new QualifiedIdentifier(qualifiedIdPieces.getFirst().getStartPosition(),
 				qualifiedIdPieces.getLast().getEndPosition(), qualifiedIdPieces.toArray(new SpelNodeImpl[0]));
@@ -942,7 +943,7 @@ private Token eatToken(TokenKind expectedKind) {
 		}
 		if (t.kind != expectedKind) {
 			throw internalException(t.startPos, SpelMessage.NOT_EXPECTED_TOKEN,
-					expectedKind.toString().toLowerCase(), t.getKind().toString().toLowerCase());
+					expectedKind.toString().toLowerCase(Locale.ROOT), t.getKind().toString().toLowerCase(Locale.ROOT));
 		}
 		return t;
 	}
@@ -1038,7 +1039,7 @@ public String toString(@Nullable Token t) {
 		if (t.getKind().hasPayload()) {
 			return t.stringValue();
 		}
-		return t.kind.toString().toLowerCase();
+		return t.kind.toString().toLowerCase(Locale.ROOT);
 	}
 
 	private void checkOperands(Token token, @Nullable SpelNodeImpl left, @Nullable SpelNodeImpl right) {

spring-expression/src/main/java/org/springframework/expression/spel/standard/Tokenizer.java

@@ -19,6 +19,7 @@
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.Locale;
 
 import org.springframework.expression.spel.InternalParseException;
 import org.springframework.expression.spel.SpelMessage;
@@ -455,7 +456,7 @@ private void lexIdentifier() {
 		// Check if this is the alternative (textual) representation of an operator (see
 		// alternativeOperatorNames)
 		if ((this.pos - start) == 2 || (this.pos - start) == 3) {
-			String asString = new String(subarray).toUpperCase();
+			String asString = new String(subarray).toUpperCase(Locale.ROOT);
 			int idx = Arrays.binarySearch(ALTERNATIVE_OPERATOR_NAMES, asString);
 			if (idx >= 0) {
 				pushOneCharOrTwoCharToken(TokenKind.valueOf(asString), start, subarray);

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/CallMetaDataContext.java

@@ -385,7 +385,7 @@ protected List<SqlParameter> reconcileParameters(List<SqlParameter> parameters)
 				if (meta.isReturnParameter()) {
 					param = declaredParams.get(getFunctionReturnName());
 					if (param == null && !getOutParameterNames().isEmpty()) {
-						param = declaredParams.get(getOutParameterNames().get(0).toLowerCase());
+						param = declaredParams.get(getOutParameterNames().get(0).toLowerCase(Locale.ROOT));
 					}
 					if (param == null) {
 						throw new InvalidDataAccessApiUsageException(
@@ -488,15 +488,15 @@ public Map<String, Object> matchInParameterValuesWithCallParameters(SqlParameter
 				String parameterName = parameter.getName();
 				String parameterNameToMatch = obtainMetaDataProvider().parameterNameToUse(parameterName);
 				if (parameterNameToMatch != null) {
-					callParameterNames.put(parameterNameToMatch.toLowerCase(), parameterName);
+					callParameterNames.put(parameterNameToMatch.toLowerCase(Locale.ROOT), parameterName);
 				}
 				if (parameterName != null) {
 					if (parameterSource.hasValue(parameterName)) {
 						matchedParameters.put(parameterName,
 								SqlParameterSourceUtils.getTypedValue(parameterSource, parameterName));
 					}
 					else {
-						String lowerCaseName = parameterName.toLowerCase();
+						String lowerCaseName = parameterName.toLowerCase(Locale.ROOT);
 						if (parameterSource.hasValue(lowerCaseName)) {
 							matchedParameters.put(parameterName,
 									SqlParameterSourceUtils.getTypedValue(parameterSource, lowerCaseName));
@@ -556,7 +556,7 @@ else if (logger.isInfoEnabled()) {
 				String parameterName = parameter.getName();
 				String parameterNameToMatch = provider.parameterNameToUse(parameterName);
 				if (parameterNameToMatch != null) {
-					callParameterNames.put(parameterNameToMatch.toLowerCase(), parameterName);
+					callParameterNames.put(parameterNameToMatch.toLowerCase(Locale.ROOT), parameterName);
 				}
 			}
 		}
@@ -680,7 +680,7 @@ protected String createParameterBinding(SqlParameter parameter) {
 	}
 
 	private static String lowerCase(@Nullable String paramName) {
-		return (paramName != null ? paramName.toLowerCase() : "");
+		return (paramName != null ? paramName.toLowerCase(Locale.ROOT) : "");
 	}
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/Db2CallMetaDataProvider.java

@@ -18,6 +18,7 @@
 
 import java.sql.DatabaseMetaData;
 import java.sql.SQLException;
+import java.util.Locale;
 
 import org.springframework.lang.Nullable;
 
@@ -73,7 +74,7 @@ public String metaDataSchemaNameToUse(@Nullable String schemaName) {
 
 		// Use current user schema if no schema specified...
 		String userName = getUserName();
-		return (userName != null ? userName.toUpperCase() : null);
+		return (userName != null ? userName.toUpperCase(Locale.ROOT) : null);
 	}
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/DerbyCallMetaDataProvider.java

@@ -18,6 +18,7 @@
 
 import java.sql.DatabaseMetaData;
 import java.sql.SQLException;
+import java.util.Locale;
 
 import org.springframework.lang.Nullable;
 
@@ -45,7 +46,7 @@ public String metaDataSchemaNameToUse(@Nullable String schemaName) {
 
 		// Use current user schema if no schema specified...
 		String userName = getUserName();
-		return (userName != null ? userName.toUpperCase() : null);
+		return (userName != null ? userName.toUpperCase(Locale.ROOT) : null);
 	}
 
 }

spring-jdbc/src/main/java/org/springframework/jdbc/core/metadata/GenericCallMetaDataProvider.java

@@ -22,6 +22,7 @@
 import java.sql.Types;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -279,10 +280,10 @@ private String identifierNameToUse(@Nullable String identifierName) {
 			return null;
 		}
 		else if (isStoresUpperCaseIdentifiers()) {
-			return identifierName.toUpperCase();
+			return identifierName.toUpperCase(Locale.ROOT);
 		}
 		else if (isStoresLowerCaseIdentifiers()) {
-			return identifierName.toLowerCase();
+			return identifierName.toLowerCase(Locale.ROOT);
 		}
 		else {
 			return identifierName;