Java by API/javax.swing.text/AbstractDocument

AbstractDocument: getText(int offset, int length)

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.URL;
import java.net.URLConnection;
import javax.swing.text.AttributeSet;
import javax.swing.text.Element;
import javax.swing.text.ElementIterator;
import javax.swing.text.StyleConstants;
import javax.swing.text.html.HTML;
import javax.swing.text.html.HTMLDocument;
import javax.swing.text.html.HTMLEditorKit;
import javax.swing.text.html.parser.ParserDelegator;
public class MainClass {
  public static void main(String args[]) throws Exception {
    URL url = new URL("http://www.jexp.ru");
    URLConnection connection = url.openConnection();
    InputStream is = connection.getInputStream();
    InputStreamReader isr = new InputStreamReader(is);
    BufferedReader br = new BufferedReader(isr);
    HTMLEditorKit htmlKit = new HTMLEditorKit();
    HTMLDocument htmlDoc = (HTMLDocument) htmlKit.createDefaultDocument();
    HTMLEditorKit.Parser parser = new ParserDelegator();
    HTMLEditorKit.ParserCallback callback = htmlDoc.getReader(0);
    parser.parse(br, callback, true);
    ElementIterator iterator = new ElementIterator(htmlDoc);
    Element element;
    while ((element = iterator.next()) != null) {
      AttributeSet attributes = element.getAttributes();
      Object name = attributes.getAttribute(StyleConstants.NameAttribute);
      if ((name instanceof HTML.Tag) && (name == HTML.Tag.H1)) {
        StringBuffer text = new StringBuffer();
        int count = element.getElementCount();
        for (int i = 0; i < count; i++) {
          Element child = element.getElement(i);
          AttributeSet childAttributes = child.getAttributes();
          if (childAttributes.getAttribute(StyleConstants.NameAttribute) == HTML.Tag.CONTENT) {
            int startOffset = child.getStartOffset();
            int endOffset = child.getEndOffset();
            int length = endOffset - startOffset;
            text.append(htmlDoc.getText(startOffset, length));
          }
        }
        System.out.println(name + ": " + text.toString());
      }
    }
  }
}

AbstractDocument: setDocumentFilter(DocumentFilter filter)

import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.text.AbstractDocument;
import javax.swing.text.AttributeSet;
import javax.swing.text.BadLocationException;
import javax.swing.text.DocumentFilter;
public class UpcaseFilter extends DocumentFilter {
  public void insertString(DocumentFilter.FilterBypass fb, int offset, String text,
      AttributeSet attr) throws BadLocationException {
    fb.insertString(offset, text.toUpperCase(), attr);
  }
  public void replace(DocumentFilter.FilterBypass fb, int offset, int length, String text,
      AttributeSet attr) throws BadLocationException {
    fb.replace(offset, length, text.toUpperCase(), attr);
  }
  public static void main(String[] args) {
    DocumentFilter dfilter = new UpcaseFilter();
    JTextArea jta = new JTextArea();
    JTextField jtf = new JTextField();
    ((AbstractDocument) jta.getDocument()).setDocumentFilter(dfilter);
    ((AbstractDocument) jtf.getDocument()).setDocumentFilter(dfilter);
    JFrame frame = new JFrame("UpcaseFilter");
    frame.getContentPane().add(jta, "Center");
    frame.getContentPane().add(jtf, "South");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200, 120);
    frame.setVisible(true);
  }
}