ZIP压缩和解压字符串

由于ZIP压缩会产生头信息, 所以当字符串长度没有达到一定规模的时候, 压缩后的长度可能比原来的还长

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

    // 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："+ZipUtil.compress(str).length());

        System.out.println("解压缩："+ZipUtil.uncompress(ZipUtil.compress(str)));
    }
}