package com.msj.utils;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.util.zip.GZIPInputStream;

import java.util.zip.GZIPOutputStream;

/**

* gzip压缩（数据压缩）

*/

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{

//读取文件

String readPath = System.getProperty("user.dir") + File.separatorChar + "sources" + File.separatorChar + "006.jpg";

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);

//测试压缩

byte[] ret1 = GzipUtils.gzip(data);

System.out.println("压缩之后大小:" + ret1.length);

byte[] ret2 = GzipUtils.ungzip(ret1);

System.out.println("还原之后大小:" + ret2.length);

//写出文件

String writePath = System.getProperty("user.dir") + File.separatorChar + "receive" + File.separatorChar + "006.jpg";

FileOutputStream fos = new FileOutputStream(writePath);

fos.write(ret2);

fos.close();

}

}