Java 使用 GZIP 进行压缩和解压缩

转自：http://www.oschina.net/code/snippet_12_259

. [代码]CompressFileGZIP.java    

01	import java.util.zip.GZIPOutputStream;

02	import java.io.FileOutputStream;

03	import java.io.FileInputStream;

04	import java.io.FileNotFoundException;

05	import java.io.IOException;

06

07

/**

08	* -----------------------------------------------------------------------------

09	* Used to provide an example of compressing a file using the GZIP Format.

10

*

11	* @version 1.0

12	* @author  Jeffrey M. Hunter  ([e-mail])

13	* @author  http://www.idevelopment.info

14	* -----------------------------------------------------------------------------

15

*/

16

17	public class CompressFileGZIP {

18

19

/**

20	* Perform file compression.

21	* @param inFileName Name of the file to be compressed

22

*/

23	private static void doCompressFile(String inFileName) {

24

25

try {

26

27	System.out.println("Creating the GZIP output stream.");

28	String outFileName = inFileName + ".gz";

29	GZIPOutputStream out = null;

30

try {

31	out = new GZIPOutputStream(new FileOutputStream(outFileName));

32	} catch(FileNotFoundException e) {

33	System.err.println("Could not create file: " + outFileName);

34	System.exit(1);

35

}

36

37

38	System.out.println("Opening the input file.");

39	FileInputStream in = null;

40

try {

41	in = new FileInputStream(inFileName);

42	} catch (FileNotFoundException e) {

43	System.err.println("File not found. " + inFileName);

44	System.exit(1);

45

}

46

47	System.out.println("Transfering bytes from input file to GZIP Format.");

48	byte[] buf = new byte[1024];

49

int len;

50	while((len = in.read(buf)) > 0) {

51	out.write(buf, 0, len);

52

}

53	in.close();

54

55	System.out.println("Completing the GZIP file");

56	out.finish();

57	out.close();

58

59	} catch (IOException e) {

60	e.printStackTrace();

61	System.exit(1);

62

}

63

64

}

65

66

/**

67	* Sole entry point to the class and application.

68	* @param args Array of String arguments.

69

*/

70	public static void main(String[] args) {

71

72	if (args.length != 1) {

73	System.err.println("Usage: java CompressFileGZIP filename");

74

} else {

75	doCompressFile(args[0]);

76

}

77

78

79

}

80

81

}

2. [代码]UncompressFileGZIP.java    

001	import java.util.zip.GZIPInputStream;

002	import java.io.FileOutputStream;

003	import java.io.FileInputStream;

004	import java.io.FileNotFoundException;

005	import java.io.IOException;

006

007

/**

008	* -----------------------------------------------------------------------------

009	* Used to provide an example of uncompressing a file in the GZIP Format.

010

*

011	* @version 1.0

012	* @author  Jeffrey M. Hunter  ([e-mail])

013	* @author  http://www.idevelopment.info

014	* -----------------------------------------------------------------------------

015

*/

016

017	public class UncompressFileGZIP {

018

019

/**

020	* Uncompress the incoming file.

021	* @param inFileName Name of the file to be uncompressed

022

*/

023	private static void doUncompressFile(String inFileName) {

024

025

try {

026

027	if (!getExtension(inFileName).equalsIgnoreCase("gz")) {

028	System.err.println("File name must have extension of \".gz\"");

029	System.exit(1);

030

}

031

032	System.out.println("Opening the compressed file.");

033	GZIPInputStream in = null;

034

try {

035	in = new GZIPInputStream(new FileInputStream(inFileName));

036	} catch(FileNotFoundException e) {

037	System.err.println("File not found. " + inFileName);

038	System.exit(1);

039

}

040

041	System.out.println("Open the output file.");

042	String outFileName = getFileName(inFileName);

043	FileOutputStream out = null;

044

try {

045	out = new FileOutputStream(outFileName);

046	} catch (FileNotFoundException e) {

047	System.err.println("Could not write to file. " + outFileName);

048	System.exit(1);

049

}

050

051	System.out.println("Transfering bytes from compressed file to the output file.");

052	byte[] buf = new byte[1024];

053

int len;

054	while((len = in.read(buf)) > 0) {

055	out.write(buf, 0, len);

056

}

057

058	System.out.println("Closing the file and stream");

059	in.close();

060	out.close();

061

062	} catch (IOException e) {

063	e.printStackTrace();

064	System.exit(1);

065

}

066

067

}

068

069

/**

070	* Used to extract and return the extension of a given file.

071	* @param f Incoming file to get the extension of

072	* @return <code>String</code> representing the extension of the incoming

073	*         file.

074

*/

075	public static String getExtension(String f) {

076	String ext = "";

077	int i = f.lastIndexOf('.');

078

079	if (i > 0 &&  i < f.length() - 1) {

080	ext = f.substring(i+1);

081

}

082	return ext;

083

}

084

085

/**

086	* Used to extract the filename without its extension.

087	* @param f Incoming file to get the filename

088	* @return <code>String</code> representing the filename without its

089	*         extension.

090

*/

091	public static String getFileName(String f) {

092	String fname = "";

093	int i = f.lastIndexOf('.');

094

095	if (i > 0 &&  i < f.length() - 1) {

096	fname = f.substring(0,i);

097

}

098	return fname;

099

}

100

101

/**

102	* Sole entry point to the class and application.

103	* @param args Array of String arguments.

104

*/

105	public static void main(String[] args) {

106

107	if (args.length != 1) {

108	System.err.println("Usage: java UncompressFileGZIP gzipfile");

109

} else {

110	doUncompressFile(args[0]);

111

}

112

113

}

114

115

}