org.springframework.web.util.HtmlCharacterEntityReferences Maven / Gradle / Ivy
/*
* Copyright 2002-2023 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.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.web.util;
import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* Represents a set of character entity references defined by the
* HTML 4.0 standard.
*
* A complete description of the HTML 4.0 character set can be found
* at https://www.w3.org/TR/html4/charset.html.
*
* @author Juergen Hoeller
* @author Martin Kersten
* @author Craig Andrews
* @since 1.2.1
*/
class HtmlCharacterEntityReferences {
private static final String PROPERTIES_FILE = "HtmlCharacterEntityReferences.properties";
static final char REFERENCE_START = '&';
static final String DECIMAL_REFERENCE_START = "&#";
static final String HEX_REFERENCE_START = "&#x";
static final char REFERENCE_END = ';';
static final char CHAR_NULL = (char) -1;
private final String[] characterToEntityReferenceMap = new String[3000];
private final Map entityReferenceToCharacterMap = new HashMap<>(512);
/**
* Returns a new set of character entity references reflecting the HTML 4.0 character set.
*/
public HtmlCharacterEntityReferences() {
Properties entityReferences = new Properties();
// Load reference definition file
InputStream is = HtmlCharacterEntityReferences.class.getResourceAsStream(PROPERTIES_FILE);
if (is == null) {
throw new IllegalStateException(
"Cannot find reference definition file [HtmlCharacterEntityReferences.properties] as class path resource");
}
try {
try {
entityReferences.load(is);
}
finally {
is.close();
}
}
catch (IOException ex) {
throw new IllegalStateException(
"Failed to parse reference definition file [HtmlCharacterEntityReferences.properties]: " + ex.getMessage());
}
// Parse reference definition properties
Enumeration keys = entityReferences.propertyNames();
while (keys.hasMoreElements()) {
String key = (String) keys.nextElement();
int referredChar = Integer.parseInt(key);
Assert.isTrue((referredChar < 1000 || (referredChar >= 8000 && referredChar < 10000)),
() -> "Invalid reference to special HTML entity: " + referredChar);
int index = (referredChar < 1000 ? referredChar : referredChar - 7000);
String reference = entityReferences.getProperty(key);
this.characterToEntityReferenceMap[index] = REFERENCE_START + reference + REFERENCE_END;
this.entityReferenceToCharacterMap.put(reference, (char) referredChar);
}
}
/**
* Return the number of supported entity references.
*/
public int getSupportedReferenceCount() {
return this.entityReferenceToCharacterMap.size();
}
/**
* Return true if the given character is mapped to a supported entity reference.
*/
public boolean isMappedToReference(char character) {
return isMappedToReference(character, WebUtils.DEFAULT_CHARACTER_ENCODING);
}
/**
* Return true if the given character is mapped to a supported entity reference.
*/
public boolean isMappedToReference(char character, String encoding) {
return (convertToReference(character, encoding) != null);
}
/**
* Return the reference mapped to the given character, or {@code null} if none found.
*/
@Nullable
public String convertToReference(char character) {
return convertToReference(character, WebUtils.DEFAULT_CHARACTER_ENCODING);
}
/**
* Return the reference mapped to the given character, or {@code null} if none found.
* @since 4.1.2
*/
@Nullable
public String convertToReference(char character, String encoding) {
if (encoding.startsWith("UTF-")){
return switch (character){
case '<' -> "<";
case '>' -> ">";
case '"' -> """;
case '&' -> "&";
case '\'' -> "'";
default -> null;
};
}
else if (character < 1000 || (character >= 8000 && character < 10000)) {
int index = (character < 1000 ? character : character - 7000);
String entityReference = this.characterToEntityReferenceMap[index];
if (entityReference != null) {
return entityReference;
}
}
return null;
}
/**
* Return the char mapped to the given entityReference or -1.
*/
public char convertToCharacter(String entityReference) {
Character referredCharacter = this.entityReferenceToCharacterMap.get(entityReference);
if (referredCharacter != null) {
return referredCharacter;
}
return CHAR_NULL;
}
}