getfiledemo.java

从网络取得文件

import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import javax.swing.*;

public class GetFileDemo extends JFrame{
	
	private static final long serialVersionUID = 1L;
	JTextField jtfUrl;//URL
	JButton jbGetFile;
	JLabel jlInfo;
	
	public GetFileDemo(){
		super("");
		
		Container container=getContentPane();
		jtfUrl=new JTextField(18);
		jbGetFile=new JButton("");
		jlInfo=new JLabel(); 
		JPanel p=new JPanel();
		p.add(jtfUrl);
		p.add(jbGetFile);
		container.add(p,BorderLayout.NORTH);
		container.add(jlInfo,BorderLayout.CENTER);
		
		jbGetFile.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent ent){
				try{
					jlInfo.setText("");
					URL url=new URL(jtfUrl.getText());    
					InputStream in=url.openStream();  
					String outFilename=JOptionPane.showInputDialog(GetFileDemo.this,"");
					FileOutputStream out=new FileOutputStream(outFilename);
					byte[] buffer=new byte[1024];
					int length;
					while ((length=in.read(buffer))!=-1){
						out.write(buffer,0,length);
					} 
					out.close();
					in.close();
					jlInfo.setText("");
				}
				catch(Exception ex){
					ex.printStackTrace();
					jlInfo.setText("");
				}
			}
		});
	
		setSize(320,100);
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	}
	
	public static void main(String[] args){
		new GetFileDemo();
	}
}