TemplateFilter sends HTML content through an
* Html/XML parser to a set of Templates. Each Html/XML tag may
* dynamically invoke a Java method present in the Templates.
* The dynamically-generated content from evaluating the Html/XML tags is
* returned to the caller.
*
* The following configuration parameters are used to initialize this
* Filter.
*
templates
* name.class is examined to determine which class to
* use for each template. Then name is used as the prefix
* for other template specific properties if any. If
* name.class does not exist, then name
* is assumed to be the class name, and there are no template specific
* properties for the template. Methods in the template classes will be
* invoked to process the XML/HTML tags present in the content.
* session
* subtype
* encoding
* outputEncoding
* tagPrefix
* tagPrefix option is not specified for an individual template.
* TemplateHandler class is similar, but not identical to
* running a FilterHandler with the FileHandler and
* the TemplateFilter. The differences between the two should
* be resolved.
*
* Note: The templates property accepts a list of
* class names or tokens that could be used to represent
* class names. If class names are used, all
* template classes share the TemplateHandler's properties prefix.
*
* @author Stephen Uhler (stephen.uhler@sun.com)
* @author Colin Stevens (colin.stevens@sun.com)
* @version 2.5
*/
public class TemplateFilter implements Filter {
private static final String TEMPLATES = "templates";
private static final String SESSION = "session";
Server server;
String prefix;
String subtype; // media subtype to filter (must be text)
String session = "SessionID"; // our session ID property name
private TemplateRunner runner; // The template object for our class
public boolean
init(Server server, String prefix)
{
Properties props = server.props;
this.server = server;
this.prefix = prefix;
String name = props.getProperty(prefix + TEMPLATES, "");
subtype = "text/" + props.getProperty(prefix + "subtype", "");
try {
runner = new TemplateRunner(server, prefix, name);
} catch (Exception e) {
server.log(Server.LOG_ERROR, prefix,
"Can't instantiate " + e.getMessage());
return false;
}
session = props.getProperty(prefix + SESSION, session);
return true;
}
/**
* No action before request is made.
*/
public boolean
respond(Request request)
{
/*
* Until we can deal with content encodings, make sure
* the client doesn't "support" any.
*/
request.headers.remove("Accept-encoding");
return false;
}
/**
* Filters all HTML files, or files that are likely to be html files,
* specifically, those whose "Content-Type" starts with "text/".
*/
public boolean
shouldFilter(Request request, MimeHeaders headers)
{
String type = headers.get("Content-Type");
boolean filter= ((type != null) &&
type.toLowerCase().startsWith("text/"));
request.log(Server.LOG_DIAGNOSTIC, prefix + "type: " + type +
" filter?: " + filter);
return filter;
}
/**
* Evaluates the content as html/XML tags, if the file is (or has now been
* converted to) "text/html".
*/
public byte[]
filter(Request request, MimeHeaders headers, byte[] content)
{
if (headers.get("Content-Type").toLowerCase().startsWith(subtype)
== false) {
request.log(Server.LOG_DIAGNOSTIC, prefix +
" Not " + subtype + ", skipping");
return content;
}
/*
* Get the cookie out of the request object (presumably from the
* sessionhandler). If not there, don't use cookies.
*/
String sessionId = request.props.getProperty(session);
String encoding = request.props.getProperty(prefix + "encoding",
request.props.getProperty("encoding"));
String outputEncoding = request.props.getProperty(prefix +
"outputEncoding", encoding);
if (sessionId == null) {
sessionId = "noCookie";
request.log(Server.LOG_WARNING, "template not using cookies");
}
/*
* Process the content as a template. If there is an error,
* leave the content unchanged.
*/
String enc = null;
if (encoding != null) {
try {
enc = new String(content, encoding);
} catch(UnsupportedEncodingException e) {
request.log(Server.LOG_WARNING, "template Error: " +
e.getMessage());
}
}
if (enc == null) {
enc = new String(content);
}
String result = runner.process(request, enc, sessionId);
if (result != null) {
if (outputEncoding != null) {
try {
return result.getBytes(outputEncoding);
} catch (UnsupportedEncodingException e) {
request.log(Server.LOG_WARNING, e.getMessage());
}
}
return result.getBytes();
} else {
request.log(Server.LOG_INFORMATIONAL, "template Error: " +
runner.getError());
return content;
}
}
}