1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
import com.icl.saxon.expr.StringValue;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.*;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;
import java.io.File;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
/**
* SaxonServlet. Transforms a supplied input document using a supplied stylesheet
*/
public class SaxonServlet extends HttpServlet {
/**
* service() - accept request and produce response<BR>
* URL parameters: <UL>
* <li>source - URL of source document</li>
* <li>style - URL of stylesheet</li>
* <li>clear-stylesheet-cache - if set to yes, empties the cache before running.
* </UL>
* @param req The HTTP request
* @param res The HTTP response
*/
public void service(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException
{
String source = req.getParameter("source");
String style = req.getParameter("style");
String clear = req.getParameter("clear-stylesheet-cache");
if (clear!=null && clear.equals("yes")) {
clearCache();
}
try {
apply(style, source, req, res);
} catch (TransformerException err) {
res.getOutputStream().println("Error applying stylesheet: " + err.getMessage());
}
}
/**
* getServletInfo<BR>
* Required by Servlet interface
*/
public String getServletInfo() {
return "Calls SAXON to apply a stylesheet to a source document";
}
/**
* Apply stylesheet to source document
*/
private void apply(String style, String source,
HttpServletRequest req, HttpServletResponse res)
throws TransformerException, java.io.IOException {
ServletOutputStream out = res.getOutputStream();
if (style==null) {
out.println("No style parameter supplied");
return;
}
if (source==null) {
out.println("No source parameter supplied");
return;
}
try {
Templates pss = tryCache(style);
Transformer transformer = pss.newTransformer();
Properties details = pss.getOutputProperties();
String mime = pss.getOutputProperties().getProperty(OutputKeys.MEDIA_TYPE);
if (mime==null) {
// guess
res.setContentType("text/html");
} else {
res.setContentType(mime);
}
Enumeration p = req.getParameterNames();
while (p.hasMoreElements()) {
String name = (String)p.nextElement();
if (!(name.equals("style") || name.equals("source"))) {
String value = req.getParameter(name);
transformer.setParameter(name, new StringValue(value));
}
}
String path = getServletContext().getRealPath(source);
if (path==null) {
throw new TransformerException("Source file " + source + " not found");
}
File sourceFile = new File(path);
transformer.transform(new StreamSource(sourceFile), new StreamResult(out));
} catch (Exception err) {
out.println(err.getMessage());
err.printStackTrace();
}
}
/**
* Maintain prepared stylesheets in memory for reuse
*/
private synchronized Templates tryCache(String url) throws TransformerException, java.io.IOException {
String path = getServletContext().getRealPath(url);
if (path==null) {
throw new TransformerException("Stylesheet " + url + " not found");
}
Templates x = (Templates)cache.get(path);
if (x==null) {
TransformerFactory factory = TransformerFactory.newInstance();
x = factory.newTemplates(new StreamSource(new File(path)));
cache.put(path, x);
}
return x;
}
/**
* Clear the cache. Useful if stylesheets have been modified, or simply if space is
* running low. We let the garbage collector do the work.
*/
private synchronized void clearCache() {
cache = new Hashtable();
}
private Hashtable cache = new Hashtable();
}
|
