Java的压缩、解压及压缩加密、解密解压 样例

           为了节约带宽、加快传送速度，http协议支持gzip的压缩，但假设我们的app与后台不是通过http协议通讯的。那么压缩、解压这个流程须要自己写。以下给出compress和decompress的代码：

   public static byte[] compress(byte[] data) throws Exception {   
       ByteArrayOutputStream baos = new ByteArrayOutputStream();   
       // 压缩  
       GZIPOutputStream gos = new GZIPOutputStream(baos);   
       gos.write(data, 0, data.length);   
       gos.finish();   
       baos.flush();  
       baos.close();   
       return <span style="font-family: Arial, Helvetica, sans-serif;">baos.toByteArray()</span><span style="font-family: Arial, Helvetica, sans-serif;">;  </span>
   } 

   public static byte[] decompress(byte[] data) throws Exception {   
   	GZIPInputStream  bis = new GZIPInputStream(new ByteInputStream(data, data.length));
   	ByteArrayOutputStream bos=new ByteArrayOutputStream();
   	byte[] buf=new byte[20480];
   	int len=0;
   	while ((len=bis.read(buf))>0){
   		bos.write(buf, 0, len);
   	}
   	bis.close();
   	bos.close();
   	return <span style="font-family: Arial, Helvetica, sans-serif;">bos.toByteArray()</span><span style="font-family: Arial, Helvetica, sans-serif;">;   	</span>
   }  

           尽快压缩后的数据不可视，但有心人非常easy通过拦截数据包非常快猜想到这是gzip压缩格式并给出解压程式，对于游戏领域、金融领域的应用，通讯过程的加密尤为重要。

     Blowfish算法免费、速度快。不宜破解（关键是key数据不要泄露），在及时加密、解密中应用广泛。以下以Blowfish算法为例简单讲下数据的压缩、加密盒解密、解压过程。

  1、定义keySpec。用来储存key数据的object：

static private SecretKeySpec keySpec;

byte[] key=KeyGenerator.getInstance("Blowfish").generateKey().getEncoded();

keySpec = new SecretKeySpec(key, "Blowfish");

  2、再定义getCipher方法，依据mode获得加密/解密的Cipher Object:

	static private Cipher getCipher (int mode) {
		try {
			Cipher cipher = Cipher.getInstance("Blowfish");
			cipher.init(mode, keySpec);
			return cipher;
		} catch (Exception ex) {
			throw new KryoException(ex);
		}
	}

3、以下是对w_str的压缩、加密和解密、解压：

   public static void main(String[] args) throws IOException, NoSuchAlgorithmException{
   
   	keySpec = new SecretKeySpec(KeyGenerator.getInstance("Blowfish").generateKey().getEncoded(), "Blowfish");
   	String w_src="这是整數數組[1, -105, 104, 101, 108, 108, 111, 119, 111, 114, 108, 100, -17, -68, -116, -28, -72, -83, -26, -106, -121, -17, -68, -116, -25, -71, -127, -23, -85, -108, -17, -68, -116, -25, -80, -95, -23, -85, -108, -17, -68, -116, -25, -82, -128, -28, -67, -109]";
		Cipher cipher = getCipher(Cipher.ENCRYPT_MODE);
   	ByteArrayOutputStream bos=new ByteArrayOutputStream();   	
		GZIPOutputStream gos=new GZIPOutputStream(new CipherOutputStream(bos, cipher));
		gos.write(w_src.getBytes());
		gos.close();
		bos.close();
		byte[] data=bos.toByteArray();
		//压缩加密后data仅仅有135byte长度，还是很可观的。

		//decrypt & decompress
		cipher = getCipher(Cipher.DECRYPT_MODE);
		ByteArrayInputStream bis=new ByteArrayInputStream(data);
		GZIPInputStream  input = new GZIPInputStream(new CipherInputStream(bis,cipher));				
		ByteArrayOutputStream baos=new ByteArrayOutputStream();
		byte[] w_buffer=new byte[2048];
		int len=0;
   	while ((len=input.read(w_buffer))>0){
   		baos.write(w_buffer, 0, len);
   	}
   	bis.close();
   	input.close();
   	baos.close();
   	byte[] w_ret=baos.toByteArray();
   	String w_out_str=new String(w_ret);
   	System.out.println(w_out_str);
   }

当然，对于极度重要的数据。为了安全起见，权衡加解密速度、破解难度等方面。个人建议还是用AES不正确称加密。

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