package com.doumee.core.utils;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

import org.apache.commons.io.output.ByteArrayOutputStream;

public class CompressUtil {
	/**
	 * 对字节数组进行gzip压缩
	 * <p>
	 * 
	 * @author jgzhang2, 2014-8-13
	 * 
	 *            ：压缩前的字节数组
	 * @return：压缩后的字节数组
	 */
	public static byte[] compressByGzip(byte[] str) {
		if (str == null || str.length == 0) {
			return null;
		}
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		GZIPOutputStream gzip;
		try {
			gzip = new GZIPOutputStream(out);
			gzip.write(str);
			gzip.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return out.toByteArray();
	}

	/**
	 * <p>
	 * 
	 * @author jgzhang2, 2014-8-16
	 * 
	 * @param bytesToUncompress
	 * @param encoding
	 * @return
	 * @throws IOException
	 */
	public static byte[] uncompressByGzip(byte[] bytesToUncompress,
			String encoding) throws IOException {
		if (bytesToUncompress == null || bytesToUncompress.length == 0) {
			return null;
		}
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		ByteArrayInputStream in = new ByteArrayInputStream(bytesToUncompress);

		GZIPInputStream gunzip = new GZIPInputStream(in);
		byte[] buffer = new byte[256];
		int n;
		while ((n = gunzip.read(buffer)) >= 0) {
			out.write(buffer, 0, n);
		}

		return out.toByteArray();

	}
}