java中Gzip压缩与解压技术

java中Gzip压缩与解压技术

java中自带有Gzip压缩与解压的类，GZIPOutputStream类是用于压缩的类，里面传递的参数是字节流对象。GZIPIntputStream类是用于解压的类，传递的参数也是字节流。Gzip压缩需要把文件压缩成xxx.gz文件（不过我试了以.g或.z及其他格式，也是可以解压出来的，不过打开可能乱码）。

GZIPOutputStream在写完数据后，需要调用finish()方法。

以下是代码实现：

GZipUtils

package com.zhang;


/**
 * Created by Administrator on 2016/7/18.
 */
public class GzipUtils {

private static final int BUFFER = 1024;

public static void compress(File orginalFile, File compressFile) throws IOException {
if (orginalFile != null && orginalFile.isFile() && compressFile != null && compressFile.isFile()) {
            FileInputStream is = new FileInputStream(orginalFile);
            FileOutputStream os = new FileOutputStream(compressFile);
            compress(is, os);
            is.close();
            os.close();
        }
    }

public static void compress(String orginalFile, String compressFile) throws IOException {
if (orginalFile != null && compressFile != null) {
            FileInputStream is = new FileInputStream(orginalFile);
            FileOutputStream os = new FileOutputStream(compressFile);
            compress(is, os);
            is.close();
            os.close();
        }
    }

public static byte[] compress(byte[] bytes) throws IOException {
if (bytes != null) {
            ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            compress(bais, baos);
            bytes = baos.toByteArray();
            bais.close();
            baos.close();
        }
return bytes;
    }

public static void compress(InputStream is, OutputStream os) throws IOException {
        GZIPOutputStream gos = new GZIPOutputStream(os);
int len = 0;
byte[] buffer = new byte[BUFFER];
while ((len = is.read(buffer)) != -1) {
            gos.write(buffer, 0, len);
        }
        gos.finish();
        gos.flush();
        gos.close();
    }

public static void deCompress(File compressFile, File orginalFile) throws IOException {
if (orginalFile != null && orginalFile.isFile() && compressFile != null && compressFile.isFile()) {
            FileInputStream is = new FileInputStream(compressFile);
            FileOutputStream os = new FileOutputStream(orginalFile);
            deCompress(is, os);
            is.close();
            os.close();
        }
    }

public static void deCompress(String compressFile, String orginalFile) throws IOException {
if (orginalFile != null && compressFile != null) {
            FileInputStream is = new FileInputStream(compressFile);
            FileOutputStream os = new FileOutputStream(orginalFile);
            deCompress(is, os);
            is.close();
            os.close();
        }
    }

public static byte[] deCompress(byte[] bytes) throws IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
        deCompress(bais, baos);
        bytes = baos.toByteArray();
        bais.close();
        baos.close();
return bytes;
    }


public static void deCompress(InputStream is, OutputStream os) throws IOException {
        GZIPInputStream gis = new GZIPInputStream(is);
int len = 0;
byte[] buffer = new byte[BUFFER];
while ((len = gis.read(buffer)) != -1) {
            os.write(buffer, 0, len);
        }
        os.flush();
        gis.close();
    }


}

程序入口

public class Test {
public static void main(String[] args) throws IOException {
        stringTest();
        fileTest();
        byteTest();
    }

public static void fileTest() throws IOException {
        String orginal = "C:\\MyPrivate\\1.txt";
        String compress = "C:\\MyPrivate\\1.gz";
        String decompress = "C:\\MyPrivate\\1(1).txt";

        File orginalFile = new File(orginal);
        File compressFile = new File(compress);
        File decompressFile = new File(decompress);
if (!compressFile.exists()) {
            compressFile.createNewFile();
        }
if (!decompressFile.exists()) {
            decompressFile.createNewFile();
        }
        GzipUtils.compress(orginalFile, compressFile);
        GzipUtils.deCompress(compressFile, decompressFile);
    }

public static void stringTest() throws IOException {
        String orginal = "C:\\MyPrivate\\2.png";
        String compress = "C:\\MyPrivate\\2.gz";
        String decompress = "C:\\MyPrivate\\2(2).png";

        GzipUtils.compress(orginal, compress);

        GzipUtils.deCompress(compress, decompress);
    }

public static void byteTest() throws IOException {
        String test = "[e-mail],[e-mail],[e-mail]@zlex.org,[e-mail]," +
"[e-mail]@zlex.org,[e-mail],[e-mail]";

        System.out.println("compress before:" + test.getBytes().length);
byte[] bytes = GzipUtils.compress(test.getBytes());
        System.out.println("compress after:" + bytes.length);
        bytes = GzipUtils.deCompress(bytes);
        System.out.println("decompress after:" + bytes.length);
    }
}

控制台打印结果(文件测试也是可以的,就不显示了)：

compress before:156
compress after:48
decompress after:156