java字符串压缩解压示例

我测试的字符串是jquery源码。

明文长度:78082
压缩后：26566
加密长度：54746
再压缩:41647
-----------------------------
密文长度:41647
解压缩：54746
解密后：26566
再解压：78082
-----------------------------
比对成功

des需要jar：sun.misc.base64decoder.jar

test

public static void main(string[] args) throws exception {
  string cont = "";
  string cont2=jm(yjy(cont));
  if(cont.equals(cont2)){
   system.out.println("比对成功");
  }else{
   system.out.println("比对失败");
  }
 }

 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;
 }

desutil

import java.io.ioexception;
import java.security.securerandom;

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);
 }
}

ziputil2
.

import java.io.bytearrayinputstream;
import java.io.bytearrayoutputstream;
import java.io.ioexception;
import java.util.zip.gzipinputstream;
import java.util.zip.gzipoutputstream;

// 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();
 }

}