org.apache.log4j.helpers.Transform Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.log4j.helpers;
/**
* Utility class for transforming strings.
*
* @author Ceki Gülcü
* @author Michael A. McAngus
*/
public class Transform {
private static final String CDATA_START = "";
private static final String CDATA_PSEUDO_END = "]]>";
private static final String CDATA_EMBEDED_END = CDATA_END + CDATA_PSEUDO_END + CDATA_START;
private static final int CDATA_END_LEN = CDATA_END.length();
/**
* This method takes a string which may contain HTML tags (ie, <b>,
* <table>, etc) and replaces any '<', '>' , '&' or '"'
* characters with respective predefined entity references.
*
* @param input The text to be converted.
* @return The input string with the special characters replaced.
*/
static public String escapeTags(final String input) {
// Check if the string is null, zero length or devoid of special characters
// if so, return what was sent in.
if (input == null || input.length() == 0 || (input.indexOf('"') == -1 && input.indexOf('&') == -1
&& input.indexOf('<') == -1 && input.indexOf('>') == -1)) {
return input;
}
// Use a StringBuilder in lieu of String concatenation -- it is
// much more efficient this way.
StringBuilder buf = new StringBuilder(input.length() + 6);
char ch = ' ';
int len = input.length();
for (int i = 0; i < len; i++) {
ch = input.charAt(i);
if (ch > '>') {
buf.append(ch);
} else if (ch == '<') {
buf.append("<");
} else if (ch == '>') {
buf.append(">");
} else if (ch == '&') {
buf.append("&");
} else if (ch == '"') {
buf.append(""");
} else {
buf.append(ch);
}
}
return buf.toString();
}
/**
* Ensures that embeded CDEnd strings (]]>) are handled properly within
* message, NDC and throwable tag text.
*
* @param buf StringBuffer holding the XML data to this point. The initial
* CDStart (<![CDATA[) and final CDEnd (]]>) of the CDATA
* section are the responsibility of the calling method.
* @param str The String that is inserted into an existing CDATA Section within
* buf.
*/
static public void appendEscapingCDATA(final StringBuffer buf, final String str) {
if (str != null) {
int end = str.indexOf(CDATA_END);
if (end < 0) {
buf.append(str);
} else {
int start = 0;
while (end > -1) {
buf.append(str.substring(start, end));
buf.append(CDATA_EMBEDED_END);
start = end + CDATA_END_LEN;
if (start < str.length()) {
end = str.indexOf(CDATA_END, start);
} else {
return;
}
}
buf.append(str.substring(start));
}
}
}
}