frmmain.java

该压缩文件中共包含16个非常实用的java学习实例

import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.io.*;
public class FrmMain extends Applet implements Runnable, ActionListener
{
	private TextArea msg;
	private JButton b1;
	private JButton b2;
	private JButton b3;
	private JButton b4;
	private JPanel p;
	
	private FileInputStream fin=null;
	private FileOutputStream fout=null;
	
	private String pathname=null;
	private String filename=null;
	private String pathname_to=null;
		
	private byte buf[];
	
	Thread th;
		
	public void init()
	{
		msg=new TextArea(50,20);
			
		b1=new JButton("选择");
		b2=new JButton("加密");
		b3=new JButton("保存");
		b4=new JButton("解密");
		b1.setFont(new Font("DialogInput", 0, 12));
		b2.setFont(new Font("DialogInput", 0, 12));
		b3.setFont(new Font("DialogInput", 0, 12));
		b4.setFont(new Font("DialogInput", 0, 12));
		p=new JPanel();
		this.setLayout(new BorderLayout());
		this.add("Center",msg);
		this.add("South",p);
		
		p.add(b1);
		p.add(b3);
		p.add(b2);
		p.add(b4);
		
		b1.addActionListener(this);
		b2.addActionListener(this);
		b3.addActionListener(this);
		b4.addActionListener(this);
	}
	public void run()
	{
		try
		{
			fin=new FileInputStream(pathname);
			fout=new FileOutputStream(pathname_to);
			buf=new byte[1024]; 
			msg.append("正在加密文件"+filename+"\n");
			int i=fin.read(buf);
			while(i!=-1)
			{
				for(int j=0;j<i;j++)
				{
					if(buf[j]!=127)
						buf[j]++;
					else
						buf[j]=-128;	
				}
				fout.write(buf,0,i);
				i=fin.read(buf);	
			}
			msg.append("文件加密成功!\n");
		}
		catch(Exception e)
		{
			msg.append(e.getMessage()+"\n");
		}
		
	}
	public static void main(String[] args)
	{
		FrmMain app=new FrmMain();
		Frame frm=new Frame("文件加密工具");
		app.init();
		app.start();
		frm.add(app);
		frm.setSize(500,300);
		frm.setResizable(false);
		Dimension d=Toolkit.getDefaultToolkit().getScreenSize();
		Dimension f=frm.getSize();
		frm.setLocation(d.width/2-f.width/2,d.height/2-f.height/2);
		frm.show();
		frm.addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent evt)
			{
				System.exit(0);
			}
		});
	}

	public void actionPerformed(ActionEvent e) 
	{
		if(e.getActionCommand().equals("选择"))
		{
			FileDialog fdlg=new FileDialog(new Frame(),"选择要加密的文件",FileDialog.LOAD);
			fdlg.setVisible(true);
			msg.append("要加密的文件是：     "+fdlg.getDirectory()+fdlg.getFile()+"\n");
			filename=fdlg.getFile();
			pathname=fdlg.getDirectory()+fdlg.getFile();
			return;
		}
		if(e.getActionCommand().equals("保存"))
		{
			FileDialog fdlg=new FileDialog(new Frame(),"选择文件的存放位置",FileDialog.SAVE);
			fdlg.setVisible(true);
			msg.append("加密并保存到：     "+fdlg.getDirectory()+fdlg.getFile()+"\n");
			pathname_to=fdlg.getDirectory()+fdlg.getFile();
			return;
		}
		if(e.getActionCommand().equals("加密"))
		{
			if(pathname.equals("")||pathname.equals("nullnull"))
				{
					JOptionPane.showMessageDialog(null,"没有选择要加密的文件","错误",JOptionPane.ERROR_MESSAGE);
					return;
				}
				
			th=new Thread(this);
			th.start();
			return;
		}
		if(e.getActionCommand().equals("解密"))
		{
			//if(pathname.equals("")||pathname.equals("nullnull"))
				//{
					JOptionPane.showMessageDialog(null,"没有选择要加密的文件","错误",JOptionPane.ERROR_MESSAGE);
					return;
				//}
				
		//	th=new Thread(this);
			//th.start();
			//return;
		}
	}
}