Cipher加密解密

package com.test;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.security.InvalidKeyException;
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;

public class CipherTest
{

	public static void main(String[] args)
	{
		try
		{
			//secretEncrypt();
			
			
			secretDecrypt();
			
			
		}
		catch (Exception e)
		{
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

	private static void secretEncrypt() throws NoSuchAlgorithmException,
			NoSuchPaddingException, InvalidKeyException, FileNotFoundException,
			IOException, IllegalBlockSizeException, BadPaddingException
	{
		Cipher cipher = Cipher.getInstance("AES");
		SecretKey key = KeyGenerator.getInstance("AES").generateKey();
		
		//加密
		cipher.init(Cipher.ENCRYPT_MODE, key);
		
		OutputStream os = new FileOutputStream("secret_key");
		ObjectOutputStream oos = new ObjectOutputStream(os);
		oos.writeObject(key);
		oos.close();
		os.close();
		
		byte[] result = cipher.doFinal("aab".getBytes());
		
		os = new FileOutputStream("secret_data");
		BufferedOutputStream bos = new BufferedOutputStream(os);
		bos.write(result);
		bos.close();
		os.close();
		
		System.out.println(new String(result));
	}

	private static void secretDecrypt() throws NoSuchAlgorithmException,
			NoSuchPaddingException, FileNotFoundException, IOException,
			ClassNotFoundException, InvalidKeyException,
			IllegalBlockSizeException, BadPaddingException
	{
		//解密
		Cipher cipher = Cipher.getInstance("AES");
		
		InputStream is = new FileInputStream("secret_key");
		ObjectInputStream ois = new ObjectInputStream(is);
		SecretKey key = (SecretKey)ois.readObject();
		ois.close();
		is.close();
		
		cipher.init(Cipher.DECRYPT_MODE, key);
		
		is = new FileInputStream("secret_data");
		BufferedInputStream bis = new BufferedInputStream(is);
		
//		ByteArrayOutputStream baos = new ByteArrayOutputStream();
	
//方法一：
//		byte[] rs = new byte[1024];
//		int length = 0;
//		while((length = bis.read(rs)) != -1){
//			baos.write(rs, 0, length);
//		}
		
//方法二：
		byte[] rs = new byte[bis.available()];
		int length = bis.read(rs);
		int total = 0;
		while(total < bis.available()){
			total += length;
			
			length = bis.read(rs, total, bis.available() - total);
		}
		
		//System.out.println(new String(cipher.doFinal(baos.toByteArray())));
		System.out.println(new String(cipher.doFinal(rs)));
//		baos.close();
		bis.close();
		is.close();
	}
	
}