java DES 例子

package aosa.safemedia.util;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;

import com.sun.org.apache.xerces.internal.impl.dv.util.Base64;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;


public class Encryption {
    
    private void createKey() {
        try {
            // 得到密钥的实例 以什么方式加密。加密的方式比较多。
            KeyGenerator kg = KeyGenerator.getInstance("DES");
            kg.init(56);
            SecretKey key = kg.generateKey();
            // 将生成的密钥对象写入文件。
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(
                    new FileOutputStream(new File("e:\\key.obj")));
            objectOutputStream.writeObject(key);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    
    private static Key getKey(String KeyFilePath) {
        Key key = null;
        try {
            // 将生成的密钥对象从文件中读取出来，然后再强制转换成一个密钥对象。
            ObjectInputStream objectInputStream = new ObjectInputStream(
                    new FileInputStream(new File(KeyFilePath)));
            key = (Key) objectInputStream.readObject();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return key;
    }

    
    public  byte[] encrypt(String source) {
        byte[] target = null;
        try {
            byte[] center = source.getBytes("UTF-8");
            Key key = getKey("e:\\key.obj");
            Cipher cipher = Cipher.getInstance("DES");

            cipher.init(Cipher.ENCRYPT_MODE, key);

            target = cipher.doFinal(center);
            
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        
        return target;
    }

    
    public  byte[] decrypt(byte[] source) {
        byte[] dissect = null;
        try {
            Key key = getKey("e:\\key.obj");
            Cipher cipher = Cipher.getInstance("DES");
            cipher.init(Cipher.DECRYPT_MODE, key);// 使用私钥解密
            dissect = cipher.doFinal(source);
            
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        }
        return dissect;
    }
    
    
    
    public void encodeByteToFile(byte[] bytes){
        BASE64Encoder base64encoder = new BASE64Encoder();
        try {
            base64encoder.encode(bytes,new FileOutputStream(new File("D:\\t.txt")));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        
    }
    
    
    
    
    public byte[] getByteFromFile(){
        BASE64Decoder base64decoder = new BASE64Decoder();
        byte[] encodeByte = null;
        try {
            encodeByte = base64decoder.decodeBuffer(new FileInputStream(new File("D:\\t.txt")));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return encodeByte;
    }
    
    
    public  void writeByteToFile(byte[] b, String filePath) {
        File file = new File(filePath);
        if (!file.exists()) {
            try {
                file.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        FileOutputStream fileOutputStream;
        try {
            fileOutputStream = new FileOutputStream(file);
            
            fileOutputStream.write(b);
            fileOutputStream.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    
    //测试使用。
//    public static void main(String[] args) {
//        Encryption encryption = new Encryption();
//        //encryption.dateEncrypt(encryption.encrypt("yangtao"));
//        System.out.println(new String(encryption.decrypt(encryption.getByteFromFile())));
//    }
}