A simple XML parser that builds a tree from SAX events
/*
Java Swing, 2nd Edition
By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole
ISBN: 0-596-00408-7
Publisher: O'Reilly
*/
// VSX.java
//A simple XML parser that builds a tree from SAX events.
//
import java.io.File;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeModel;
import javax.swing.tree.TreeModel;
import javax.xml.parsers.SAXParser;
import javax.xml.parsers.SAXParserFactory;
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class VSX {
public TreeModel parse(String filename) {
SAXParserFactory factory = SAXParserFactory.newInstance();
XMLTreeHandler handler = new XMLTreeHandler();
try {
// Parse the input.
SAXParser saxParser = factory.newSAXParser();
saxParser.parse(new File(filename), handler);
} catch (Exception e) {
System.err.println("File Read Error: " + e);
e.printStackTrace();
return new DefaultTreeModel(new DefaultMutableTreeNode("error"));
}
return new DefaultTreeModel(handler.getRoot());
}
public static class XMLTreeHandler extends DefaultHandler {
private DefaultMutableTreeNode root, currentNode;
public DefaultMutableTreeNode getRoot() {
return root;
}
// SAX Parser Handler methods...
public void startElement(String namespaceURI, String lName,
String qName, Attributes attrs) throws SAXException {
String eName = lName; // Element name
if ("".equals(eName))
eName = qName;
Tag t = new Tag(eName, attrs);
DefaultMutableTreeNode newNode = new DefaultMutableTreeNode(t);
if (currentNode == null) {
root = newNode;
} else {
// Must not be the root node...
currentNode.add(newNode);
}
currentNode = newNode;
}
public void endElement(String namespaceURI, String sName, String qName)
throws SAXException {
currentNode = (DefaultMutableTreeNode) currentNode.getParent();
}
public void characters(char buf[], int offset, int len)
throws SAXException {
String s = new String(buf, offset, len).trim();
((Tag) currentNode.getUserObject()).addData(s);
}
}
public static class Tag {
private String name;
private String data;
private Attributes attr;
public Tag(String n, Attributes a) {
name = n;
attr = a;
}
public String getName() {
return name;
}
public Attributes getAttributes() {
return attr;
}
public void setData(String d) {
data = d;
}
public String getData() {
return data;
}
public void addData(String d) {
if (data == null) {
setData(d);
} else {
data += d;
}
}
public String getAttributesAsString() {
StringBuffer buf = new StringBuffer(256);
for (int i = 0; i < attr.getLength(); i++) {
buf.append(attr.getQName(i));
buf.append("=\"");
buf.append(attr.getValue(i));
buf.append("\"");
}
return buf.toString();
}
public String toString() {
String a = getAttributesAsString();
return name + ": " + a + (data == null ? "" : " (" + data + ")");
}
}
public static void main(String args[]) {
JFrame frame = new JFrame("VSX Test");
VSX parser = new VSX();
JTree tree = new JTree(parser.parse("build.xml"));
frame.getContentPane().add(new JScrollPane(tree));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 400);
frame.setVisible(true);
}
}
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