Java压缩技术(六) BZIP2——Commons实现
2015-12-22 18:21
615 查看
想要把一整套算法都整理出来,的确是件非常老心费力的事情!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201512/12ab0bdbbc295d73c75960829ea44d6d.gif)
但是如果一件事情不能有始有终,难免会有遗憾!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201409/fd156494540f006b2f1813627354f9cd.gif)
索性,继续整理!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
BZip2与GZip有什么渊源,我这里不深究。我要说的只是,这两种算法,你在linux下都可以找到相应的操作命令。
GZip
压缩
gzip <file> 将得到压缩文件<file>.gz,同时删除文件<file>
解压缩
gzip -d <file>.gz 将得到压缩文件<file>,同时删除文件<file>.gz
BZip2与之相当,几乎没有什么差别~~
BZip2
压缩
bzip2 <file> 将得到压缩文件<file>.bz2,同时删除文件<file>
解压缩
bzip2 -d <file>.bz2 将得到压缩文件<file>,同时删除文件<file>.bz2
除了命令不同外,几乎是一样的!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
再说实现。GZIP是JDK自带的算法实现,但BZip2则不曾享受这个待遇。
![](https://oscdn.geek-share.com/Uploads/Images/Content/201512/12ab0bdbbc295d73c75960829ea44d6d.gif)
不过,强大的Apache坚决不会让这些个在Linux下如鱼得水的算法在Java世界中销声匿迹。Apache在Commons
Compress中提供了相应的实现。同时,还包括众所周知的tar、cpio、zip等算法实现,其中最为丰富的当属zip实现了!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
我继续依葫芦画瓢~~~
BZip2CompressorOutputStream类用于压缩
BZip2CompressorInputStream类用于解压缩
先说压缩实现,BZip2CompressorOutputStream只有一个方法用于压缩,就是带定长的write方法。简单调用如下文所示:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 数据压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void compress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorOutputStream gos = new BZip2CompressorOutputStream(os);
int count;
byte data[] = new byte[BUFFER];
while ((count = is.read(data, 0, BUFFER)) != -1) {
gos.write(data, 0, count);
}
gos.finish();
gos.flush();
gos.close();
}
与GZip实现有何差别?除了换掉了GZIPOutputStream没有任何差别。
![](https://oscdn.geek-share.com/Uploads/Images/Content/201409/fd156494540f006b2f1813627354f9cd.gif)
解压缩就更不用说了,BZip2CompressorInputStream提供了一个带定长的read方法。简单调用如下文所示:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 数据解压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void decompress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorInputStream gis = new BZip2CompressorInputStream(is);
int count;
byte data[] = new byte[BUFFER];
while ((count = gis.read(data, 0, BUFFER)) != -1) {
os.write(data, 0, count);
}
gis.close();
}
嗯,没什么难度!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
IT这行就是这样,只要你肯用心,能触类旁通,就能融会贯通!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
给一个完整实现:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 2010-4-15
*/
package org.zlex.commons.compress.compress;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream;
import org.apache.commons.compress.compressors.bzip2.BZip2CompressorOutputStream;
/**
* BZip2工具
*
* @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
* @since 1.0
*/
public abstract class BZip2Utils {
public static final int BUFFER = 1024;
public static final CharSequence EXT = ".bz2";
/**
* 数据压缩
*
* @param data
* @return
* @throws Exception
*/
public static byte[] compress(byte[] data) throws Exception {
ByteArrayInputStream bais = new ByteArrayInputStream(data);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 压缩
compress(bais, baos);
byte[] output = baos.toByteArray();
baos.flush();
baos.close();
bais.close();
return output;
}
/**
* 文件压缩
*
* @param file
* @throws Exception
*/
public static void compress(File file) throws Exception {
compress(file, true);
}
/**
* 文件压缩
*
* @param file
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void compress(File file, boolean delete) throws Exception {
FileInputStream fis = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(file.getPath() + EXT);
compress(fis, fos);
fis.close();
fos.flush();
fos.close();
if (delete) {
file.delete();
}
}
/**
* 数据压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void compress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorOutputStream gos = new BZip2CompressorOutputStream(os);
int count;
byte data[] = new byte[BUFFER];
while ((count = is.read(data, 0, BUFFER)) != -1) {
gos.write(data, 0, count);
}
gos.finish();
gos.flush();
gos.close();
}
/**
* 文件压缩
*
* @param path
* @throws Exception
*/
public static void compress(String path) throws Exception {
compress(path, true);
}
/**
* 文件压缩
*
* @param path
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void compress(String path, boolean delete) throws Exception {
File file = new File(path);
compress(file, delete);
}
/**
* 数据解压缩
*
* @param data
* @return
* @throws Exception
*/
public static byte[] decompress(byte[] data) throws Exception {
ByteArrayInputStream bais = new ByteArrayInputStream(data);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 解压缩
decompress(bais, baos);
data = baos.toByteArray();
baos.flush();
baos.close();
bais.close();
return data;
}
/**
* 文件解压缩
*
* @param file
* @throws Exception
*/
public static void decompress(File file) throws Exception {
decompress(file, true);
}
/**
* 文件解压缩
*
* @param file
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void decompress(File file, boolean delete) throws Exception {
FileInputStream fis = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(file.getPath().replace(EXT,
""));
decompress(fis, fos);
fis.close();
fos.flush();
fos.close();
if (delete) {
file.delete();
}
}
/**
* 数据解压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void decompress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorInputStream gis = new BZip2CompressorInputStream(is);
int count;
byte data[] = new byte[BUFFER];
while ((count = gis.read(data, 0, BUFFER)) != -1) {
os.write(data, 0, count);
}
gis.close();
}
/**
* 文件解压缩
*
* @param path
* @throws Exception
*/
public static void decompress(String path) throws Exception {
decompress(path, true);
}
/**
* 文件解压缩
*
* @param path
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void decompress(String path, boolean delete) throws Exception {
File file = new File(path);
decompress(file, delete);
}
}
对应再来个测试用例,测试用例如下所示:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 2010-4-13
*/
package org.zlex.commons.compress.compress;
import static org.junit.Assert.assertEquals;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import org.junit.Test;
/**
* BZip2
*
* @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
* @since 1.0
*/
public class BZip2UtilsTest {
private String inputStr = "zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org";
@Test
public final void testDataCompress() throws Exception {
byte[] input = inputStr.getBytes();
System.err.println("原文:\t" + inputStr);
System.err.println("长度:\t" + input.length);
byte[] data = BZip2Utils.compress(input);
System.err.println("压缩后:\t");
System.err.println("长度:\t" + data.length);
byte[] output = BZip2Utils.decompress(data);
String outputStr = new String(output);
System.err.println("解压缩后:\t" + outputStr);
System.err.println("长度:\t" + output.length);
assertEquals(inputStr, outputStr);
}
@Test
public final void testFileCompress() throws Exception {
FileOutputStream fos = new FileOutputStream("d:/f.txt");
fos.write(inputStr.getBytes());
fos.flush();
fos.close();
BZip2Utils.compress("d:/f.txt");
BZip2Utils.decompress("d:/f.txt.bz2");
File file = new File("d:/f.txt");
FileInputStream fis = new FileInputStream(file);
DataInputStream dis = new DataInputStream(fis);
byte[] data = new byte[(int) file.length()];
dis.readFully(data);
fis.close();
String outputStr = new String(data);
assertEquals(inputStr, outputStr);
}
}
虽然,两种算法在代码实现上几乎没有什么差别,但在压缩上想要看到效果,还真让我费了点事!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201409/fd156494540f006b2f1813627354f9cd.gif)
控制台输出如下所示:
引用
原文: zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org
长度: 529
压缩后:
长度: 76
解压缩后: zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org
长度: 529
529字节-->76字节!
GZIP本身不需要太长的内容,经过压缩就能体现出压缩效果,而BZip2则需要压缩很长的内容时,才能体现其压缩效果,这说明BZip2更适合大数据压缩?!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
Commons Compress不仅支持BZip2算法实现,同时也支持GZip算法实现。对于GZip算法实现,与Java原生实现基本上没有什么差别。其源代码分析,仅仅是做了简单的包装。
不过有必要提及的一点是,Commons Compress为压缩(GZip和BZip2)构建了压缩算法工厂类CompressorStreamFactory。通过这个类可以方便的构建GZip和BZip2的输入输出流,关键字分别为“gz”和“bzip2”。
GZip
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
// GzipCompressorInputStream
CompressorInputStream gzipIn = new CompressorStreamFactory()
.createCompressorInputStream("gz", is);
// GzipCompressorOutputStream
CompressorOutputStream gzipOut = new CompressorStreamFactory()
.createCompressorOutputStream("gz", os);
BZip2
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
// BZip2CompressorInputStream
CompressorInputStream bzip2In = new CompressorStreamFactory()
.createCompressorInputStream("bzip2", is);
// BZip2CompressorOutputStream
CompressorOutputStream bzip2Out = new CompressorStreamFactory()
.createCompressorOutputStream("bzip2", os);
GZip和BZip2在算法实现步骤上基本上没有什么差别,如果有必要统一,可按上述代码实现!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
![](https://oscdn.geek-share.com/Uploads/Images/Content/201512/12ab0bdbbc295d73c75960829ea44d6d.gif)
但是如果一件事情不能有始有终,难免会有遗憾!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201409/fd156494540f006b2f1813627354f9cd.gif)
索性,继续整理!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
BZip2与GZip有什么渊源,我这里不深究。我要说的只是,这两种算法,你在linux下都可以找到相应的操作命令。
GZip
压缩
gzip <file> 将得到压缩文件<file>.gz,同时删除文件<file>
解压缩
gzip -d <file>.gz 将得到压缩文件<file>,同时删除文件<file>.gz
BZip2与之相当,几乎没有什么差别~~
BZip2
压缩
bzip2 <file> 将得到压缩文件<file>.bz2,同时删除文件<file>
解压缩
bzip2 -d <file>.bz2 将得到压缩文件<file>,同时删除文件<file>.bz2
除了命令不同外,几乎是一样的!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
再说实现。GZIP是JDK自带的算法实现,但BZip2则不曾享受这个待遇。
![](https://oscdn.geek-share.com/Uploads/Images/Content/201512/12ab0bdbbc295d73c75960829ea44d6d.gif)
不过,强大的Apache坚决不会让这些个在Linux下如鱼得水的算法在Java世界中销声匿迹。Apache在Commons
Compress中提供了相应的实现。同时,还包括众所周知的tar、cpio、zip等算法实现,其中最为丰富的当属zip实现了!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
我继续依葫芦画瓢~~~
BZip2CompressorOutputStream类用于压缩
BZip2CompressorInputStream类用于解压缩
先说压缩实现,BZip2CompressorOutputStream只有一个方法用于压缩,就是带定长的write方法。简单调用如下文所示:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 数据压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void compress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorOutputStream gos = new BZip2CompressorOutputStream(os);
int count;
byte data[] = new byte[BUFFER];
while ((count = is.read(data, 0, BUFFER)) != -1) {
gos.write(data, 0, count);
}
gos.finish();
gos.flush();
gos.close();
}
与GZip实现有何差别?除了换掉了GZIPOutputStream没有任何差别。
![](https://oscdn.geek-share.com/Uploads/Images/Content/201409/fd156494540f006b2f1813627354f9cd.gif)
解压缩就更不用说了,BZip2CompressorInputStream提供了一个带定长的read方法。简单调用如下文所示:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 数据解压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void decompress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorInputStream gis = new BZip2CompressorInputStream(is);
int count;
byte data[] = new byte[BUFFER];
while ((count = gis.read(data, 0, BUFFER)) != -1) {
os.write(data, 0, count);
}
gis.close();
}
嗯,没什么难度!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
IT这行就是这样,只要你肯用心,能触类旁通,就能融会贯通!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
给一个完整实现:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 2010-4-15
*/
package org.zlex.commons.compress.compress;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream;
import org.apache.commons.compress.compressors.bzip2.BZip2CompressorOutputStream;
/**
* BZip2工具
*
* @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
* @since 1.0
*/
public abstract class BZip2Utils {
public static final int BUFFER = 1024;
public static final CharSequence EXT = ".bz2";
/**
* 数据压缩
*
* @param data
* @return
* @throws Exception
*/
public static byte[] compress(byte[] data) throws Exception {
ByteArrayInputStream bais = new ByteArrayInputStream(data);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 压缩
compress(bais, baos);
byte[] output = baos.toByteArray();
baos.flush();
baos.close();
bais.close();
return output;
}
/**
* 文件压缩
*
* @param file
* @throws Exception
*/
public static void compress(File file) throws Exception {
compress(file, true);
}
/**
* 文件压缩
*
* @param file
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void compress(File file, boolean delete) throws Exception {
FileInputStream fis = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(file.getPath() + EXT);
compress(fis, fos);
fis.close();
fos.flush();
fos.close();
if (delete) {
file.delete();
}
}
/**
* 数据压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void compress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorOutputStream gos = new BZip2CompressorOutputStream(os);
int count;
byte data[] = new byte[BUFFER];
while ((count = is.read(data, 0, BUFFER)) != -1) {
gos.write(data, 0, count);
}
gos.finish();
gos.flush();
gos.close();
}
/**
* 文件压缩
*
* @param path
* @throws Exception
*/
public static void compress(String path) throws Exception {
compress(path, true);
}
/**
* 文件压缩
*
* @param path
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void compress(String path, boolean delete) throws Exception {
File file = new File(path);
compress(file, delete);
}
/**
* 数据解压缩
*
* @param data
* @return
* @throws Exception
*/
public static byte[] decompress(byte[] data) throws Exception {
ByteArrayInputStream bais = new ByteArrayInputStream(data);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// 解压缩
decompress(bais, baos);
data = baos.toByteArray();
baos.flush();
baos.close();
bais.close();
return data;
}
/**
* 文件解压缩
*
* @param file
* @throws Exception
*/
public static void decompress(File file) throws Exception {
decompress(file, true);
}
/**
* 文件解压缩
*
* @param file
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void decompress(File file, boolean delete) throws Exception {
FileInputStream fis = new FileInputStream(file);
FileOutputStream fos = new FileOutputStream(file.getPath().replace(EXT,
""));
decompress(fis, fos);
fis.close();
fos.flush();
fos.close();
if (delete) {
file.delete();
}
}
/**
* 数据解压缩
*
* @param is
* @param os
* @throws Exception
*/
public static void decompress(InputStream is, OutputStream os)
throws Exception {
BZip2CompressorInputStream gis = new BZip2CompressorInputStream(is);
int count;
byte data[] = new byte[BUFFER];
while ((count = gis.read(data, 0, BUFFER)) != -1) {
os.write(data, 0, count);
}
gis.close();
}
/**
* 文件解压缩
*
* @param path
* @throws Exception
*/
public static void decompress(String path) throws Exception {
decompress(path, true);
}
/**
* 文件解压缩
*
* @param path
* @param delete
* 是否删除原始文件
* @throws Exception
*/
public static void decompress(String path, boolean delete) throws Exception {
File file = new File(path);
decompress(file, delete);
}
}
对应再来个测试用例,测试用例如下所示:
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
/**
* 2010-4-13
*/
package org.zlex.commons.compress.compress;
import static org.junit.Assert.assertEquals;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import org.junit.Test;
/**
* BZip2
*
* @author <a href="mailto:zlex.dongliang@gmail.com">梁栋</a>
* @since 1.0
*/
public class BZip2UtilsTest {
private String inputStr = "zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org";
@Test
public final void testDataCompress() throws Exception {
byte[] input = inputStr.getBytes();
System.err.println("原文:\t" + inputStr);
System.err.println("长度:\t" + input.length);
byte[] data = BZip2Utils.compress(input);
System.err.println("压缩后:\t");
System.err.println("长度:\t" + data.length);
byte[] output = BZip2Utils.decompress(data);
String outputStr = new String(output);
System.err.println("解压缩后:\t" + outputStr);
System.err.println("长度:\t" + output.length);
assertEquals(inputStr, outputStr);
}
@Test
public final void testFileCompress() throws Exception {
FileOutputStream fos = new FileOutputStream("d:/f.txt");
fos.write(inputStr.getBytes());
fos.flush();
fos.close();
BZip2Utils.compress("d:/f.txt");
BZip2Utils.decompress("d:/f.txt.bz2");
File file = new File("d:/f.txt");
FileInputStream fis = new FileInputStream(file);
DataInputStream dis = new DataInputStream(fis);
byte[] data = new byte[(int) file.length()];
dis.readFully(data);
fis.close();
String outputStr = new String(data);
assertEquals(inputStr, outputStr);
}
}
虽然,两种算法在代码实现上几乎没有什么差别,但在压缩上想要看到效果,还真让我费了点事!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201409/fd156494540f006b2f1813627354f9cd.gif)
控制台输出如下所示:
引用
原文: zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org
长度: 529
压缩后:
长度: 76
解压缩后: zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org,zlex@zlex.org,snowolf@zlex.org,zlex.snowolf@zlex.org
长度: 529
529字节-->76字节!
GZIP本身不需要太长的内容,经过压缩就能体现出压缩效果,而BZip2则需要压缩很长的内容时,才能体现其压缩效果,这说明BZip2更适合大数据压缩?!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
Commons Compress不仅支持BZip2算法实现,同时也支持GZip算法实现。对于GZip算法实现,与Java原生实现基本上没有什么差别。其源代码分析,仅仅是做了简单的包装。
不过有必要提及的一点是,Commons Compress为压缩(GZip和BZip2)构建了压缩算法工厂类CompressorStreamFactory。通过这个类可以方便的构建GZip和BZip2的输入输出流,关键字分别为“gz”和“bzip2”。
GZip
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
// GzipCompressorInputStream
CompressorInputStream gzipIn = new CompressorStreamFactory()
.createCompressorInputStream("gz", is);
// GzipCompressorOutputStream
CompressorOutputStream gzipOut = new CompressorStreamFactory()
.createCompressorOutputStream("gz", os);
BZip2
Java代码
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/0fd15f644694a335690493798a0b6d72.png)
// BZip2CompressorInputStream
CompressorInputStream bzip2In = new CompressorStreamFactory()
.createCompressorInputStream("bzip2", is);
// BZip2CompressorOutputStream
CompressorOutputStream bzip2Out = new CompressorStreamFactory()
.createCompressorOutputStream("bzip2", os);
GZip和BZip2在算法实现步骤上基本上没有什么差别,如果有必要统一,可按上述代码实现!
![](https://oscdn.geek-share.com/Uploads/Images/Content/201612/a6558229767b87df3caca2cbd544f611.gif)
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