/**
* class ObjectSerializer
*/
package irlab.util;

import gov.nih.nlm.nls.utils.Debug;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.zip.*;
import java.util.*;

/**
* the main function of this class is to serialzie and compress an object
* @author yezheng
*@Fun: serializer an object
*the main function of this class is to serialzie and compress an object
*
*/
public class ObjectSerializer {

public static byte[] serializeObject_compress(Object pObject){
return serializeObject(pObject, true);
}

/**
*
* @param pObject
* @param tag, if true,then compress
* @return
* @throws Exception
*/
public static byte[] serializeObject(Object pObject, boolean tag) {
byte[] returnValue = new byte[0];
try {
ByteArrayOutputStream byteStream = new ByteArrayOutputStream(5000);
ObjectOutputStream os = new ObjectOutputStream(
new BufferedOutputStream(byteStream));
os.flush();
os.writeObject(pObject);
os.flush();
// retrieves byte array
if (tag) {
returnValue = compressBytes(byteStream.toByteArray());
} else {
returnValue = byteStream.toByteArray();
}

os.close();
os = null;
} catch (Exception e) {
e.printStackTrace();
}
return (returnValue);

} // ***End public byte[] serializeObject (Object pObject)

// ================================================|Public Method
// Header|====

/**
* Method unSerializeObject
*
* @param pBytes
* @param tag, if true, need to uncompress first
* @return Object
* @exception Exception
*
*/
// ================================================|Public Method
// Header|====
public static Object unSerializeObject(byte[] pBytes, boolean tag) {
Object returnValue = null;
try {
if (true) {
pBytes = decompressBytes(pBytes);
}
ByteArrayInputStream byteStream = new ByteArrayInputStream(pBytes);
ObjectInputStream is = new ObjectInputStream(
new BufferedInputStream(byteStream));
returnValue = is.readObject();
is.close();
} catch (Exception e) {
e.printStackTrace();
}

return (returnValue);

} // ***End public Object unSerializeObject (byte[] pBytes )

public static Object unSerializeObject_decompress(byte[] pBytes)
{
return unSerializeObject(pBytes, true);
}

/**
* use class Inflater to decompress data
*
* @param input
* @return
*/
public static byte[] compressBytes(byte input[]) {
compresser.reset();//do not forgot this statement,
compresser.setInput(input);
compresser.finish();//do not forgot this statement,
byte output[] = new byte[0];
ByteArrayOutputStream o = new ByteArrayOutputStream(input.length);
try {
byte[] buf = new byte[cachesize];
int got;
while (!compresser.finished()) {
got = compresser.deflate(buf);
o.write(buf, 0, got);
}
output = o.toByteArray();
// System.out.println(“len after compress: ” +output.length);
} finally {
try {
o.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return output;
}
/**
* use class Deflater to compress data
* @param input
* @return
*/
public static byte[] decompressBytes(byte input[])
{
byte output[] = new byte[0];
decompresser.reset();
decompresser.setInput(input);
ByteArrayOutputStream o = new ByteArrayOutputStream(input.length);
try {

byte[] buf = new byte[cachesize];
int got;
while (!decompresser.finished()) {
got = decompresser.inflate(buf);
o.write(buf, 0, got);
}
output = o.toByteArray();
// System.out.println(“len after decompress: ” +output.length);
}catch(Exception e)
{
e.printStackTrace();
}finally {
try {
o.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

return output;
}

public static void test(){
String inputString = “blahblahblah8888888888888888888888888888888888888888888888999″;
System.out.println(inputString);

byte input[] = inputString.getBytes();
System.out.println(“original len = ” + input.length);

byte output[]= decompressBytes(compressBytes(input));
String outputstring = new String(output);
System.out.println(outputstring);
}

public static void testObject()

{
HashMap map = new HashMap();
map.put(“111111″, “v1111111″);
map.put(“22222222″, “v2111112″);
map.put(“333333″, “v3333333333″);
map.put(“444444444″, “v4444444″);
byte byteobj[] = serializeObject_compress(map);
byte byteobj1[] = serializeObject(map, false);
System.out.println(“size com:” + byteobj.length);
System.out.println(“size uncom:” + byteobj1.length);
HashMap map1 = (HashMap) unSerializeObject_decompress(byteobj);
if(map1.containsKey(“1″))
{
System.out.println(“sucessed”);
}
}

public static void setCachesize(int size)
{
if(size <1 || (size%256) !=0 )
{
return;
}
cachesize = size;
}

/**
* @param args
* @throws Exception
*/
public static void main(String[] args) throws Exception {
// TODO Auto-generated method stub
// Encode a String into bytes
// String inputString = “blahblahblah8888888888888888888888888888888888888888888888999″;
// test();
testObject();

}

private static Deflater compresser = new Deflater();
private static Inflater decompresser = new Inflater();
private static int cachesize = 1024;

}

Java Tar Package com.ice.tar 实现了一个tar 文档输入输出io包。使用方式接近java 中自带的 java.util.zip 包，所以也该非常容易上手，如果使用国java的zip包的话。

而且配合java 的中的GZIPInputStream 使用，就很容易实现.tar.gz 文件的访问。
步骤：
1. 读取文件，生成GZIPInputStream 流
2. 把1中生成的GZIPInputStream流传给 Java Tar Package 中的TarInputStream 流
过程非常简单，代码如下
private void visitTARGZ(P parser, File targzFile) throws IOException {
FileInputStream fileIn = null;
BufferedInputStream bufIn = null;
GZIPInputStream gzipIn = null;
TarInputStream taris = null;
try {
fileIn = new FileInputStream(targzFile);
bufIn = new BufferedInputStream(fileIn);
gzipIn = new GZIPInputStream(bufIn); //first unzip the input file stream.
taris = new TarInputStream(gzipIn);

TarEntry entry = null;
while ((entry = taris.getNextEntry()) != null) {
if (entry.isDirectory())
continue;
configure(taris, entry.getFile()); //process every entry in this tar file.
}
} finally {
taris.close();
gzipIn.close();
bufIn.close();
fileIn.close();
}
}

TarInputStream 是FilterInputStream的子类，这样所用操作又回到Java中流的概念了。 TarInputStream 提供迭代访问tar归档中所有entry文件， 其方式与ZipInputStream风常相似。

TarOutputStream 当然用法也类似了。

更多参考其官方主页： http://www.trustice.com/index.shtml
下载地址：http://www.trustice.com/java/tar/