org.springframework.web.util.HtmlCharacterEntityDecoder Maven / Gradle / Ivy
/*
* 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.
*/
package org.springframework.web.util;
/**
* Helper for decoding HTML Strings by replacing character
* entity references with the referred character.
*
* @author Juergen Hoeller
* @author Martin Kersten
* @since 1.2.1
*/
class HtmlCharacterEntityDecoder {
private static final int MAX_REFERENCE_SIZE = 10;
private final HtmlCharacterEntityReferences characterEntityReferences;
private final String originalMessage;
private final StringBuffer decodedMessage;
private int currentPosition = 0;
private int nextPotentialReferencePosition = -1;
private int nextSemicolonPosition = -2;
public HtmlCharacterEntityDecoder(HtmlCharacterEntityReferences characterEntityReferences, String original) {
this.characterEntityReferences = characterEntityReferences;
this.originalMessage = original;
this.decodedMessage = new StringBuffer(originalMessage.length());
}
public String decode() {
while (currentPosition < originalMessage.length()) {
findNextPotentialReference(currentPosition);
copyCharactersTillPotentialReference();
processPossibleReference();
}
return decodedMessage.toString();
}
private void findNextPotentialReference(int startPosition) {
nextPotentialReferencePosition = Math.max(startPosition, nextSemicolonPosition - MAX_REFERENCE_SIZE);
do {
nextPotentialReferencePosition =
originalMessage.indexOf('&', nextPotentialReferencePosition);
if (nextSemicolonPosition != -1 &&
nextSemicolonPosition < nextPotentialReferencePosition)
nextSemicolonPosition = originalMessage.indexOf(';', nextPotentialReferencePosition + 1);
boolean isPotentialReference =
nextPotentialReferencePosition != -1
&& nextSemicolonPosition != -1
&& nextPotentialReferencePosition - nextSemicolonPosition < MAX_REFERENCE_SIZE;
if (isPotentialReference) {
break;
}
if (nextPotentialReferencePosition == -1) {
break;
}
if (nextSemicolonPosition == -1) {
nextPotentialReferencePosition = -1;
break;
}
nextPotentialReferencePosition = nextPotentialReferencePosition + 1;
}
while (nextPotentialReferencePosition != -1);
}
private void copyCharactersTillPotentialReference() {
if (nextPotentialReferencePosition != currentPosition) {
int skipUntilIndex = nextPotentialReferencePosition != -1 ?
nextPotentialReferencePosition : originalMessage.length();
if (skipUntilIndex - currentPosition > 3) {
decodedMessage.append(originalMessage.substring(currentPosition, skipUntilIndex));
currentPosition = skipUntilIndex;
}
else {
while (currentPosition < skipUntilIndex)
decodedMessage.append(originalMessage.charAt(currentPosition++));
}
}
}
private void processPossibleReference() {
if (nextPotentialReferencePosition != -1) {
boolean isNumberedReference = originalMessage.charAt(currentPosition + 1) == '#';
boolean wasProcessable = isNumberedReference ? processNumberedReference() : processNamedReference();
if (wasProcessable) {
currentPosition = nextSemicolonPosition + 1;
}
else {
char currentChar = originalMessage.charAt(currentPosition);
decodedMessage.append(currentChar);
currentPosition++;
}
}
}
private boolean processNumberedReference() {
boolean isHexNumberedReference =
originalMessage.charAt(nextPotentialReferencePosition + 2) == 'x' ||
originalMessage.charAt(nextPotentialReferencePosition + 2) == 'X';
try {
int value = (!isHexNumberedReference) ?
Integer.parseInt(getReferenceSubstring(2)) :
Integer.parseInt(getReferenceSubstring(3), 16);
decodedMessage.append((char) value);
return true;
}
catch (NumberFormatException ex) {
return false;
}
}
private boolean processNamedReference() {
String referenceName = getReferenceSubstring(1);
char mappedCharacter = characterEntityReferences.convertToCharacter(referenceName);
if (mappedCharacter != HtmlCharacterEntityReferences.CHAR_NULL) {
decodedMessage.append(mappedCharacter);
return true;
}
return false;
}
private String getReferenceSubstring(int referenceOffset) {
return originalMessage.substring(nextPotentialReferencePosition + referenceOffset, nextSemicolonPosition);
}
}