java网络编程-信息发送和接收

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

package ggg.demo;
import javax.swing.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
public class        TT {
    public static void main(String args[]) {
        new DownNetFile();
    }
}
class DownNetFile extends JFrame implements ActionListener {
    JTextField infield = new JTextField(30);
    JTextArea showArea = new JTextArea();
    JButton b = new JButton("download");
    JPanel p = new JPanel();
    DownNetFile() {
        super("read network text file application");
        Container con = this.getContentPane();
        p.add(infield);
        p.add(b);
        JScrollPane jsp = new JScrollPane(showArea);
        b.addActionListener(this);
        con.add(p,"North");
        con.add(jsp,"Center"); 
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(500, 400);
        setVisible(true);
    }
    public void actionPerformed(ActionEvent e) {
        readByURL(infield.getText());
    }
    public void readByURL(String urlName) {
        try {
            URL url = new URL(urlName);//由网址创建 URL 对象
            URLConnection tc = url.openConnection();//获得 URLConnection 对象tc.connect();//设置网络连接
            InputStreamReader in = new InputStreamReader(tc.getInputStream());
            BufferedReader dis = new BufferedReader(in);//采用缓冲式输入
            String inline;
            while ((inline = dis.readLine()) != null) {
                showArea.append(inline + "\n");
            }
            dis.close();//网上资源使用结束后，数据流及时关闭
        }catch(MalformedURLException e){
                e.printStackTrace();
            }
catch(IOException e){
                e.printStackTrace();
            }
            /*访问网上资源可能产生 MalformedURLException 和 IOException 异常*/
        }
    }