htmlbrowser.java

Java网络编程实例 第10章实例.rar

package html;

import java.io.IOException;
import java.net.URL;
import javax.swing.*;
import javax.swing.text.Document;
import javax.swing.text.JTextComponent;
import java.awt.*;
import java.awt.event.*;
import javax.swing.event.*;

public class HtmlBrowser extends JFrame {
  JPanel contentPane;                  // 包含整个框架的容器
  BorderLayout borderLayoutAll = new BorderLayout();
  JLabel jLabelPrompt = new JLabel();  // 状态提示框
  JPanel jPanelMain = new JPanel();    // 包含URL编辑框和JEditorPane的容器
  BorderLayout borderLayoutMain = new BorderLayout();
  JTextField textFieldURL = new JTextField();     // URL输入框
  JEditorPane jEditorPane = new JEditorPane();    // 显示网页内容的容器

  // 构造函数
  public HtmlBrowser() {
    try {
      jbInit();       // 初始化并显示界面
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }

  // 初始化并显示界面
  private void jbInit() throws Exception  {
    contentPane = (JPanel)getContentPane();
    contentPane.setLayout(borderLayoutAll);

    jPanelMain.setLayout(borderLayoutMain);
    jLabelPrompt.setText("简单的 HTML 浏览器，请在text框内输入完整的 URL");

    textFieldURL.setText("");
    textFieldURL.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        textFieldURL_actionPerformed(e);
      }
    });

    jEditorPane.setEditable(false);
    jEditorPane.addHyperlinkListener(new javax.swing.event.HyperlinkListener() {
      public void hyperlinkUpdate(HyperlinkEvent e) {
        jEditorPane_hyperlinkUpdate(e);
      }
    });

    JScrollPane scrollPane = new JScrollPane();
    scrollPane.getViewport().add(jEditorPane);

    jPanelMain.add(textFieldURL, "North");
    jPanelMain.add(scrollPane, "Center");
    contentPane.add(jLabelPrompt, "North");
    contentPane.add(jPanelMain, "Center");

    enableEvents(AWTEvent.WINDOW_EVENT_MASK);
    this.setSize(new Dimension(600, 500));
    this.setTitle("网页浏览器");
    this.setVisible(true);
  }

  // 地址栏输入完毕后的回车消息响应
  void textFieldURL_actionPerformed(ActionEvent e) {
    try {
      jEditorPane.setPage(textFieldURL.getText());  // 显示所给的URL内容
    }
    catch(IOException ex) {
      JOptionPane msg = new JOptionPane();         // 提示对话框
      JOptionPane.showMessageDialog(this, "不正确的URL地址："+textFieldURL.getText(), "不正确的输入！", 0);
    }
  }

  // 响应页面内打开超级链接的消息
  void jEditorPane_hyperlinkUpdate(HyperlinkEvent e) {
    if(e.getEventType() == javax.swing.event.HyperlinkEvent.EventType.ACTIVATED) {
      try {
        URL url = e.getURL();                        // 从消息中得到URL地址
        jEditorPane.setPage(url);                    // 显示该URL页面的内容
        textFieldURL.setText(url.toString());        // 显示URL地址
      }
      catch(IOException io){
        JOptionPane msg = new JOptionPane();
        JOptionPane.showMessageDialog(this, "不能打开该链接！", "不正确的输入！", 0);
      }
    }
  }

  // 关闭窗口
  protected void processWindowEvent(WindowEvent e) {
    super.processWindowEvent(e);
    if (e.getID() == WindowEvent.WINDOW_CLOSING) {
      System.exit(0);
    }
  }
  // 主函数
  public static void main(String[] args) {
    new HtmlBrowser();
  }
}