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)));      }      }