java字符串压缩解压示例

 public static String yjy(String cont) throws Exception {
  System.out.println("明文长度:" + cont.length());
  // 第一次压缩
  cont = ZipUtil2.compress(cont);
  System.out.println("压缩后：" + cont.length());
  // 第一次加密
  cont = DesUtil.encrypt(cont, DesUtil.PWD_KEY);
  System.out.println("加密长度：" + cont.length());
  // 第二次压缩
  cont = ZipUtil2.compress(cont);
  System.out.println("再压缩:" + cont.length());
  return cont;
 }

 public static String jm(String cont) throws Exception {
  System.out.println("-----------------------------");
  System.out.println("密文长度:" + cont.length());

  // 第一次解压缩
  cont = ZipUtil2.uncompress(cont);
  System.out.println("解压缩：" + cont.length());

  // 第一次解密
  cont = DesUtil.decrypt(cont, DesUtil.PWD_KEY);
  System.out.println("解密后：" + cont.length());

  // 第二次解压缩
  cont = ZipUtil2.uncompress(cont);
  System.out.println("再解压：" + cont.length());

  return cont;
 }

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

import Decoder.BASE64Decoder;
import Decoder.BASE64Encoder;

public class DesUtil {

 private final static String DES = "DES";
 public final static String PWD_KEY = "MZTHPWDJM";
 public final static String ID_KEY = "MZTHIDJM";

 public static void main(String[] args) throws Exception {
  String data = "xkajsdasdk'al;ks'dl;kasl;d";
  System.err.println("加密："+encrypt(data, PWD_KEY));
  System.err.println("解密：" +decrypt(encrypt(data, PWD_KEY), PWD_KEY));
 }

 /**
  * Description 根据键值进行加密
  *
  * @param data
  * @param key
  *            加密键byte数组
  * @return
  * @throws Exception
  */
 public static String encrypt(String data, String key) throws Exception {
  byte[] bt = encrypt(data.getBytes(), key.getBytes());
  String strs = new BASE64Encoder().encode(bt);
  return strs;
 }

 /**
  * Description 根据键值进行解密
  *
  * @param data
  * @param key
  *            加密键byte数组
  * @return
  * @throws IOException
  * @throws Exception
  */
 public static String decrypt(String data, String key) throws IOException,
   Exception {
  if (data == null)
   return null;
  BASE64Decoder decoder = new BASE64Decoder();
  byte[] buf = decoder.decodeBuffer(data);
  byte[] bt = decrypt(buf, key.getBytes());
  return new String(bt);
 }

 /**
  * Description 根据键值进行加密
  *
  * @param data
  * @param key
  *            加密键byte数组
  * @return
  * @throws Exception
  */
 private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
  // 生成一个可信任的随机数源
  SecureRandom sr = new SecureRandom();

  // 从原始密钥数据创建DESKeySpec对象
  DESKeySpec dks = new DESKeySpec(key);

  // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
  SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
  SecretKey securekey = keyFactory.generateSecret(dks);

  // Cipher对象实际完成加密操作
  Cipher cipher = Cipher.getInstance(DES);

  // 用密钥初始化Cipher对象
  cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);

  return cipher.doFinal(data);
 }

 /**
  * Description 根据键值进行解密
  *
  * @param data
  * @param key
  *            加密键byte数组
  * @return
  * @throws Exception
  */
 private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
  // 生成一个可信任的随机数源
  SecureRandom sr = new SecureRandom();

  // 从原始密钥数据创建DESKeySpec对象
  DESKeySpec dks = new DESKeySpec(key);

  // 创建一个密钥工厂，然后用它把DESKeySpec转换成SecretKey对象
  SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
  SecretKey securekey = keyFactory.generateSecret(dks);

  // Cipher对象实际完成解密操作
  Cipher cipher = Cipher.getInstance(DES);

  // 用密钥初始化Cipher对象
  cipher.init(Cipher.DECRYPT_MODE, securekey, sr);

  return cipher.doFinal(data);
 }
}

// 将一个字符串按照zip方式压缩和解压缩  
public class ZipUtil2 {

 // 测试方法
 public static void main(String[] args) throws IOException {

  // 测试字符串
  String str = "";
  System.out.println("原长度：" + str.length());
  System.out.println("压缩后：" + ZipUtil2.compress(str).length());
  System.out
    .println("解压缩：" + ZipUtil2.uncompress(ZipUtil2.compress(str)));
 }

 // 压缩
 public static String compress(String str) throws IOException {
  if (str == null || str.length() == 0) {
   return str;
  }
  ByteArrayOutputStream out = new ByteArrayOutputStream();
  GZIPOutputStream gzip = new GZIPOutputStream(out);
  gzip.write(str.getBytes());
  gzip.close();
  return out.toString("ISO-8859-1");
 }

 // 解压缩
 public static String uncompress(String str) throws IOException {
  if (str == null || str.length() == 0) {
   return str;
  }
  ByteArrayOutputStream out = new ByteArrayOutputStream();
  ByteArrayInputStream in = new ByteArrayInputStream(
    str.getBytes("ISO-8859-1"));
  GZIPInputStream gunzip = new GZIPInputStream(in);
  byte[] buffer = new byte[256];
  int n;
  while ((n = gunzip.read(buffer)) >= 0) {
   out.write(buffer, 0, n);
  }
  // toString()使用平台默认编码，也可以显式的指定如toString("GBK")
  return out.toString();
 }

}