play.utils.HTML Maven / Gradle / Ivy
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package play.utils;
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 static java.util.Objects.requireNonNullElse;
import static org.apache.commons.lang3.StringUtils.isEmpty;
/*
* Copyright 2002-2005 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
*
* http://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.
*
* 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 http://www.w3.org/TR/html4/charset.html.
*
* @author Juergen Hoeller
* @author Martin Kersten
* @since 1.2.1
*/
public class HTML {
/*
* Shared instance of pre-parsed HTML character entity references.
*/
private static final HtmlCharacterEntityReferences characterEntityReferences = new HtmlCharacterEntityReferences();
/**
* Turn special characters into HTML character references. Handles complete character set defined in HTML 4.01
* recommendation.
*
* Escapes all special characters to their corresponding entity reference (e.g. <).
*
* Reference: http://www.w3.org/TR/html4/sgml/entities.html
*
*
* @param input
* the (unescaped) input string
* @return the escaped string
*/
public static String htmlEscape(String input) {
if (isEmpty(input)) {
return input;
}
StringBuilder escaped = new StringBuilder(input.length() * 2);
for (int i = 0; i < input.length(); i++) {
char character = input.charAt(i);
String reference = characterEntityReferences.convertToReference(character);
if (reference != null) {
escaped.append(reference);
} else {
escaped.append(character);
}
}
return escaped.toString();
}
public static class HtmlCharacterEntityReferences {
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 static final String PROPERTIES_FILE = "htmlentities.properties";
private final String[] characterToEntityReferenceMap = new String[3000];
private final Map entityReferenceToCharacterMap = new HashMap<>(252);
/**
* 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 [htmlentities.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 propertes.
Enumeration keys = entityReferences.propertyNames();
while (keys.hasMoreElements()) {
String key = (String) keys.nextElement();
int referredChar = Integer.parseInt(key);
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.
*
* @return 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.
*
* @param character
* The given character
* @return true if the given character is mapped to a supported entity reference
*/
public boolean isMappedToReference(char character) {
return (convertToReference(character) != null);
}
/**
* Return the reference mapped to the given character or null.
*
* @param character
* The given character
* @return The reference mapped to the given character or null
*/
public String convertToReference(char character) {
if (character < 1000 || (character >= 8000 && character < 10000)) {
int index = (character < 1000 ? character : character - 7000);
return this.characterToEntityReferenceMap[index];
}
return null;
}
/**
* Return the char mapped to the given entityReference or -1.
*
* @param entityReference
* The given entityReference
* @return The char mapped to the given entityReference or -1.
*/
public char convertToCharacter(String entityReference) {
Character referredCharacter = this.entityReferenceToCharacterMap.get(entityReference);
return requireNonNullElse(referredCharacter, CHAR_NULL);
}
}
}