import java.io.*;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

/**
 * User : Jixiaohu
 * Date : 2017-07-03.
 * Time : 16:18.
 */
public class GzipUtils {

    public static byte[] gzip(byte[] data) throws Exception {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        GZIPOutputStream gzip = new GZIPOutputStream(bos);
        gzip.write(data);
        gzip.finish();
        gzip.close();
        byte[] ret = bos.toByteArray();
        bos.close();
        return ret;
    }

    public static byte[] ungzip(byte[] data) throws Exception {
        ByteArrayInputStream bis = new ByteArrayInputStream(data);
        GZIPInputStream gzip = new GZIPInputStream(bis);
        byte[] buf = new byte[1024];
        int num = -1;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        while ((num = gzip.read(buf, 0, buf.length)) != -1) {
            bos.write(buf, 0, num);
        }
        gzip.close();
        bis.close();
        byte[] ret = bos.toByteArray();
        bos.flush();
        bos.close();
        return ret;
    }

    public static void main(String[] args) throws Exception {
        //讀取文件
        String readPath = System.getProperty("user.dir") + File.separator
                + "sources" + File.separatorChar + "006.jpg";
        System.out.println(readPath);
        File file = new File(readPath);
        FileInputStream in = new FileInputStream(file);
        byte[] data = new byte[in.available()];
        in.read(data);
        in.close();

        System.out.println("文件原始大小：" + data.length);

        //測試壓縮
        byte[] ret1 = GzipUtils.gzip(data);
        System.out.println("壓縮之後大小：" + ret1.length);

        //測試解壓縮
        byte[] ret2 = GzipUtils.ungzip(ret1);
        System.out.println("還原之後大小：" + ret2.length);

        //寫出文件
        String writePath = System.getProperty("user.dir") + File.separatorChar
                +"receive" + File.separatorChar+"006.jpg";
        System.out.println(writePath);
        FileOutputStream fos = new FileOutputStream(writePath);
        fos.write(ret2);
        fos.close();
    }
}

圖片解壓縮