文件压缩与解压缩

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

/**
 * Created by clear on 2017/9/13.
 */
public class GzipUtil {

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

    public static byte[] unzip(byte[] data) throws Exception {
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(data);
        GZIPInputStream gzipInputStream = new GZIPInputStream(byteArrayInputStream);
        byte[] buf = new byte[1024];
        int num = -1;
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
        while ((num = gzipInputStream.read(buf, 0, buf.length)) != -1) {
            byteArrayOutputStream.write(buf, 0, num);
        }

        gzipInputStream.close();
        byteArrayInputStream.close();
        byte[] res = byteArrayOutputStream.toByteArray();
        byteArrayOutputStream.flush();
        byteArrayOutputStream.close();
        return res;
    }


    public static void main(String[] args) throws Exception {
        String filePath = System.getProperty("user.dir") + File.separator + "sources" + File.separator + "slamdunk.jpg";
        FileInputStream fileInputStream = new FileInputStream(filePath);
        byte[] buf = new byte[fileInputStream.available()];
        System.out.println(buf.length);
        fileInputStream.read(buf);
        byte[] res = gzip(buf);
        System.out.println(res.length);

        byte[] res2 = unzip(res);
        System.out.println(res2.length);
        String targetFilePath = System.getProperty("user.dir") + File.separator + "receive" + File.separator + "slamdunk.jpg";
        FileOutputStream targetOutputStream = new FileOutputStream(targetFilePath);
        targetOutputStream.write(res2);
        targetOutputStream.close();
    }
}