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16 package org.outerj.daisy.summary;
17
18 import org.xmlpull.v1.XmlPullParser;
19 import org.xmlpull.mxp1.MXParser;
20 import org.outerj.daisy.xmlutil.XmlReader;
21
22 import java.io.InputStream  ;
23
24 public class HtmlSummarizer {
25
29 public static String extractSummary(InputStream is, int summaryLength) throws Exception {
30 XmlPullParser parser = new MXParser();
31 parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, true);
32 parser.setInput(new XmlReader(is));
33 int eventType = parser.getEventType();
34 StringBuffer summary = new StringBuffer (summaryLength);
35
36 while (eventType != XmlPullParser.END_DOCUMENT)
37 {
38 eventType = parser.next();
39 if (eventType == XmlPullParser.START_TAG)
40 {
41 if (!parser.getName().equals("html"))
42 return null;
43
44 while (eventType != XmlPullParser.END_TAG)
46 {
47 eventType = parser.next();
48 if (eventType == XmlPullParser.START_TAG)
49 {
50 if (parser.getName().equals("body")) {
51 eventType = parser.next();
52 int bodyElementNestingCount = 0;
53 while (bodyElementNestingCount >= 0)
54 {
55 if (eventType == XmlPullParser.START_TAG)
56 bodyElementNestingCount++;
57 else if (eventType == XmlPullParser.END_TAG)
58 bodyElementNestingCount--;
59
60 if (eventType == XmlPullParser.TEXT) {
61 String text = collapseWhitespace(parser.getText());
62 int interestingChars = Math.min(summaryLength - 3 - summary.length(), text.length());
63 summary.append(text.substring(0, interestingChars));
64 if (summary.length() == summaryLength - 3) {
65 summary.append("...");
66 return summary.toString();
67 }
68 }
69 eventType = parser.next();
70 }
71 } else {
72 goToEndElement(parser);
73 }
74 }
75 }
76 }
77 }
78
79 if (summary.length() > 0) {
80 return summary.toString();
81 } else {
82 return null;
83 }
84 }
85
86
87 private static void goToEndElement(XmlPullParser parser) throws Exception
88 {
89 int eventType = parser.next();
91 while (eventType != XmlPullParser.END_TAG)
92 {
93 if (eventType == XmlPullParser.START_TAG)
94 goToEndElement(parser);
95 eventType = parser.next();
96 }
97 }
98
99 private static String collapseWhitespace(String text) {
100 StringBuffer buffer = new StringBuffer (text.length());
101 boolean lastCharWasWhitespace = false;
102
103 for (int i = 0; i < text.length(); i++) {
104 char c = text.charAt(i);
105 switch (c) {
106 case '\n':
107 case '\r':
108 case ' ':
109 if (!lastCharWasWhitespace) {
110 buffer.append(' ');
111 lastCharWasWhitespace = true;
112 }
113 break;
114 default:
115 buffer.append(c);
116 lastCharWasWhitespace = false;
117 }
118 }
119
120 return buffer.toString();
121 }
122
123 }
124 |
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