Java的压缩、解压及压缩加密、解密解压 例子

           为了节约带宽、加快传送速度，http协议支持gzip的压缩，但如果我们的app与后台不是通过http协议通讯的，那么压缩、解压这个流程需要自己写。下面给出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，但有心人很容易通过拦截数据包很快猜想到这是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。下面以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，根据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、下面是对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只有135byte长度，还是非常可观的。//decrypt & decompresscipher = 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不对称加密。

转载请注明出处：http://blog.csdn.net/rocklee