以数据流方法读取网页内容的应用程序。程序运行时，网址从文本框中读取

    1. package ggg.demo;
    2. import javax.swing.*;
    3. import java.net.*;
    4. import java.awt.*;
    5. import java.awt.event.*;
    6. import java.io.*;
    7. public class        TT {
    8.     public static void main(String args[]) {
    9.         new DownNetFile();
    10.     }
    11. }
    12. class DownNetFile extends JFrame implements ActionListener {
    13.     JTextField infield = new JTextField(30);
    14.     JTextArea showArea = new JTextArea();
    15.     JButton b = new JButton("download");
    16.     JPanel p = new JPanel();
    17.     DownNetFile() {
    18.         super("read network text file application");
    19.         Container con = this.getContentPane();
    20.         p.add(infield);
    21.         p.add(b);
    22.         JScrollPane jsp = new JScrollPane(showArea);
    23.         b.addActionListener(this);
    24.         con.add(p,"North");
    25.         con.add(jsp,"Center");
    26.         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    27.         setSize(500, 400);
    28.         setVisible(true);
    29.     }
    30.     public void actionPerformed(ActionEvent e) {
    31.         readByURL(infield.getText());
    32.     }
    33.     public void readByURL(String urlName) {
    34.         try {
    35.             URL url = new URL(urlName);//由网址创建 URL 对象
    36.             URLConnection tc = url.openConnection();//获得 URLConnection 对象tc.connect();//设置网络连接
    37.             InputStreamReader in = new InputStreamReader(tc.getInputStream());
    38.             BufferedReader dis = new BufferedReader(in);//采用缓冲式输入
    39.             String inline;
    40.             while ((inline = dis.readLine()) != null) {
    41.                 showArea.append(inline + "\n");
    42.             }
    43.             dis.close();//网上资源使用结束后，数据流及时关闭
    44.         }catch(MalformedURLException e){
    45.                 e.printStackTrace();
    46.             }
    47. catch(IOException e){
    48.                 e.printStackTrace();
    49.             }
    50.             /*访问网上资源可能产生 MalformedURLException 和 IOException 异常*/
    51.         }
    52.     }