JAVA字符串的GZIP压缩解压缩

package com.gzip;
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 {   

 // 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();
  }   

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

      //测试字符串
     String str="%5B%7B%22lastUpdateTime%22%3A%222011-10-28+9%3A39%3A41%22%2C%22smsList%22%3A%5B%7B%22liveState%22%3A%221";   

      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)));
  }   

}