desdemo.java

java课后题的详细答案

import java.awt.Button;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Label;
import java.awt.TextField;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.security.Key;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;


public class DESDemo extends Frame
{

	private Label l;
	private Button b2,b3;
	private TextField tf1,tf2,tf3;
	byte[] plainText,cipherText,newPlainText;
	KeyGenerator KeyGen;
	Cipher  cipher;
	Key key;
	String mingwen1,miwen,mingwen2;
	public static void main(String[] args) 
    {
		new DESDemo().lanchFrame();

	}
    private void lanchFrame() 
    {
    	Frame f = new Frame();
    	f.setTitle("DESDemo");
    	f.setLocation(200, 300);
    	l = new Label("输入明文");
        b2 = new Button("输出密文");
        b3 = new Button("解密");
        tf1 = new TextField(20);
        tf2 = new TextField(20);
        tf3 = new TextField(20);
        f.setLayout(new FlowLayout());
        f.add(l);f.add(tf1);
        f.add(b2);f.add(tf2);
        f.add(b3);f.add(tf3);
        f.pack();
    	f.setVisible(true);
    	f.addWindowListener(new WindowAdapter(){
			public void windowClosing(WindowEvent e){
				System.exit(0);
			}
		});
    	b2.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent e){
				try {
					encryption_ActionPerformed();
				} catch (Exception e1) {
					e1.printStackTrace();
				}
				
		        }
			});
    	b3.addActionListener(new ActionListener(){
			public void actionPerformed(ActionEvent e){
				try {
					decryption_ActionPerformed();
				} catch (Exception e1) {
					e1.printStackTrace();
				}
				
		        }
			});
    		
    }
    public void encryption_ActionPerformed() throws Exception
    {
        mingwen1 = tf1.getText();
    	plainText=mingwen1.getBytes();
    	KeyGen=KeyGenerator.getInstance("DES");
    	KeyGen.init(56);
    	key=KeyGen.generateKey();
    	cipher=Cipher.getInstance("DES/ECB/PKCS5Padding");
    	cipher.init(Cipher.ENCRYPT_MODE,  key);
    	cipherText=cipher.doFinal(plainText);
    	tf2.setText(new String(cipherText,"UTF8"));
    }
    
    public void decryption_ActionPerformed() throws Exception
    {
    	cipher.init(Cipher.DECRYPT_MODE, key);
    	newPlainText=cipher.doFinal(cipherText);
        tf3.setText((new String(newPlainText, "UTF8")));
    	
    }
}