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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
45
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
57
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 }