加载网页内容标题并填充文本字段

import java.awt.FlowLayout;//nowjava - 时代Java 提供

import java.awt.GridLayout;

import java.awt.event.ActionEvent;

import java.awt.event.ActionListener;

import java.io.IOException;

import java.net.MalformedURLException;

import java.net.URL;

import java.net.URLConnection;


import javax.swing.JButton;

import javax.swing.JFrame;

import javax.swing.JLabel;

import javax.swing.JPanel;
/*
 from nowjava.com - 时代Java 
*/

import javax.swing.JTextField;


public class Main extends JFrame implements ActionListener, Runnable {


  Thread runner;

  String[] headers = { "Content-Length", "Content-Type", "Date", "Public",

      "Expires", "Last-Modified", "Server" };


  URL page;

  JTextField url;

  JLabel[] headerLabel = new JLabel[7];

  JTextField[] header = new JTextField[7];

  JButton readPage, clearPage, quitLoading;

  JLabel status;


  public Main() {

    super("Page Data");

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    setLayout(new GridLayout(10, 1));

    JPanel first = new JPanel();

    first.setLayout(new FlowLayout(FlowLayout.RIGHT));

    JLabel urlLabel = new JLabel("URL:");

    url = new JTextField(22);

    url.setText("https://nowjava.com");

    urlLabel.setLabelFor(url);

    first.add(urlLabel);

    first.add(url);

    add(first);


    JPanel second = new JPanel();

    second.setLayout(new FlowLayout());

    readPage = new JButton("Read Page");

    clearPage = new JButton("Clear Fields");

    quitLoading = new JButton("Quit Loading");

    readPage.setMnemonic('r');

    clearPage.setMnemonic('c');

    quitLoading.setMnemonic('q');

    readPage.setEnabled(true);

    clearPage.setEnabled(false);

    quitLoading.setEnabled(false);

    readPage.addActionListener(this);

    clearPage.addActionListener(this);

    quitLoading.addActionListener(this);

    second.add(readPage);

    second.add(clearPage);

    second.add(quitLoading);

    add(second);


    JPanel[] row = new JPanel[7];

    for (int i = 0; i < 7; i++) {

      row[i] = new JPanel();

      row[i].setLayout(new FlowLayout(FlowLayout.RIGHT));

      headerLabel[i] = new JLabel(headers[i] + ":");

      header[i] = new JTextField(22);

      headerLabel[i].setLabelFor(header[i]);

      row[i].add(headerLabel[i]);

      row[i].add(header[i]);

      add(row[i]);

    }


    JPanel last = new JPanel();

    last.setLayout(new FlowLayout(FlowLayout.LEFT));

    status = new JLabel("Enter a URL address to check.");

    last.add(status);

    add(last);

    pack();

    setVisible(true);

  }


  public void actionPerformed(ActionEvent evt) {

    Object source = evt.getSource();

    if (source == readPage) {

      try {

        page = new URL(url.getText());

        if (runner == null) {

          runner = new Thread(this);

          runner.start();

        }

        quitLoading.setEnabled(true);

        readPage.setEnabled(false);

      } catch (MalformedURLException e) {

        status.setText("Bad URL: " + page);

      }

    } else if (source == clearPage) {

      for (int i = 0; i < 7; i++)

        header[i].setText("");

      quitLoading.setEnabled(false);

      readPage.setEnabled(true);

      clearPage.setEnabled(false);

    } else if (source == quitLoading) {

      runner = null;

      url.setText("");

      quitLoading.setEnabled(false);

      readP