1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 package org.apache.log4j.helpers; 19 20 /** 21 Utility class for transforming strings. 22 23 @author Ceki Gülcü 24 @author Michael A. McAngus 25 */ 26 public class Transform { 27 28 private static final String CDATA_START = "<![CDATA["; 29 private static final String CDATA_END = "]]>"; 30 private static final String CDATA_PSEUDO_END = "]]>"; 31 private static final String CDATA_EMBEDED_END = CDATA_END + CDATA_PSEUDO_END + CDATA_START; 32 private static final int CDATA_END_LEN = CDATA_END.length(); 33 34 /** 35 * This method takes a string which may contain HTML tags (ie, 36 * <b>, <table>, etc) and replaces any 37 * '<', '>' , '&' or '"' 38 * characters with respective predefined entity references. 39 * 40 * @param input The text to be converted. 41 * @return The input string with the special characters replaced. 42 * */ 43 static public String escapeTags(final String input) { 44 //Check if the string is null, zero length or devoid of special characters 45 // if so, return what was sent in. 46 47 if(input == null 48 || input.length() == 0 49 || (input.indexOf('"') == -1 && 50 input.indexOf('&') == -1 && 51 input.indexOf('<') == -1 && 52 input.indexOf('>') == -1)) { 53 return input; 54 } 55 56 //Use a StringBuffer in lieu of String concatenation -- it is 57 //much more efficient this way. 58 59 StringBuffer buf = new StringBuffer(input.length() + 6); 60 char ch = ' '; 61 62 int len = input.length(); 63 for(int i=0; i < len; i++) { 64 ch = input.charAt(i); 65 if (ch > '>') { 66 buf.append(ch); 67 } else if(ch == '<') { 68 buf.append("<"); 69 } else if(ch == '>') { 70 buf.append(">"); 71 } else if(ch == '&') { 72 buf.append("&"); 73 } else if(ch == '"') { 74 buf.append("""); 75 } else { 76 buf.append(ch); 77 } 78 } 79 return buf.toString(); 80 } 81 82 /** 83 * Ensures that embeded CDEnd strings (]]>) are handled properly 84 * within message, NDC and throwable tag text. 85 * 86 * @param buf StringBuffer holding the XML data to this point. The 87 * initial CDStart (<![CDATA[) and final CDEnd (]]>) of the CDATA 88 * section are the responsibility of the calling method. 89 * @param str The String that is inserted into an existing CDATA Section within buf. 90 * */ 91 static public void appendEscapingCDATA(final StringBuffer buf, 92 final String str) { 93 if (str != null) { 94 int end = str.indexOf(CDATA_END); 95 if (end < 0) { 96 buf.append(str); 97 } else { 98 int start = 0; 99 while (end > -1) { 100 buf.append(str.substring(start, end)); 101 buf.append(CDATA_EMBEDED_END); 102 start = end + CDATA_END_LEN; 103 if (start < str.length()) { 104 end = str.indexOf(CDATA_END, start); 105 } else { 106 return; 107 } 108 } 109 buf.append(str.substring(start)); 110 } 111 } 112 } 113 }