[sorry - this time with message subject]
Hello,
I'm thinking of using XmlCursor / XmlBookmark to create in andex to a large
XML document. I'm wondering if I'm taking a right approach, as I found not
many real examples of XmlBookmark usage. Especially I'm wondering whether
the solution sketched below is prone to memory leaks, or otherwise
inefficient. Also, I'm not entirely sure of the exact nature of XmlCursor
vs. XmlBookmark, and it may well be that I'm doing superfluous stuff here; I
hope you like to take a look.
Say the XML is like this
<catalog>
<recordlist>
<record>
<title>short text</title>
<description>much longer text</description>
</record>
. . . . . (many records)
</recordlist>
</catalog>
My intent is to read this document into memory, then construct an index such
that each distinct word found in the description elements, acts as a key
that maps to a list of XmlBookmarks representing all records where that word
occurs. The code is like this:
CatalogDocument catalogDoc = CatalogDocument.Factory.parse(xmlFile);
Catalog catalog = catalogDoc.getCatalog();
RecordList recordList = catalog.getRecordList();
Record[] recordArray = recordList.getRecordArray();
// the index to construct
Map bookmarxIdx = new HashMap();
for(int i = 0; i < recordArray.length; i++) {
Record record = recordArray[i];
XmlCursor recordCursor = record.newCursor();
String description = record.getDescription();
StringTokenizer st = new StringTokenizer(description);
while(st.hasMoreTokens()) {
String word = st.nextToken();
List bookmarksForWord = (List) bookmarxIdx.get(word);
if(bookmarksForWord == null) {
bookmarksForWord = new ArrayList();
}
XmlCursor.XmlBookmark bookmark = new MyBookmark(word);
recordCursor.setBookmark(bookmark);
bookmarksForWord .add(recordCursor);
bookmarxIdx.put(word, bookmarxValue);
}
}
// index is created. Now I can quickly retrieve the records that contain
some
// word, for example "hello", doing this:
List cursorsForSearchterm = (List) bookmarxIdx.get("hello");
for(Iterator i = cursors.iterator(); i.hasNext();) {
XmlCursor c = (XmlCursor) i.next();
XmlCursor.XmlBookmark bm = c.getBookmark(MyBookmark.class);
c = bm.createCursor();
System.out.println("Found record: " + c.getObject().toString() );
c.dispose();
}
The catalog will ermain in application memory during its entire lifetime, so
I figured that it'd be okay to keep all the XmlCursors I'm storing in the
index -- also during application lifetime and without ever disposing of
them. Then when retrieving records, I retrieve the XmlCursors from the
index, get their bookmark, create a new XmlCursor to position itslef at that
bookmark, retrieve the record from there, and dispose of this XmlCursor.
although it works I would like to know whether this is a valid way of
dealing with these XmlCursors and XmlBookmarks, or that I'm way off the mark
here ..
thank you so much, and regards
Heikki Doeleman
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