org.apache.hadoop.io.compress.bzip2

类 CBZip2InputStream

java.lang.Object

java.io.InputStream

org.apache.hadoop.io.compress.bzip2.CBZip2InputStream

所有已实现的接口:

Closeable, AutoCloseable, BZip2Constants

public class CBZip2InputStream
extends InputStream
implements BZip2Constants

An input stream that decompresses from the BZip2 format (without the file header chars) to be read as any other stream.

The decompression requires large amounts of memory. Thus you should call the close() method as soon as possible, to force CBZip2InputStream to release the allocated memory. See CBZip2OutputStream for information about memory usage.

CBZip2InputStream reads bytes from the compressed source stream via the single byte read() method exclusively. Thus you should consider to use a buffered source stream.

Instances of this class are not threadsafe.

嵌套类概要

嵌套类

限定符和类型	类和说明
static class	CBZip2InputStream.STATE A state machine to keep track of current state of the de-coder

字段概要

字段

限定符和类型	字段和说明
static long	BLOCK_DELIMITER
static long	EOS_DELIMITER

从接口继承的字段 org.apache.hadoop.io.compress.bzip2.BZip2Constants

baseBlockSize, END_OF_BLOCK, END_OF_STREAM, G_SIZE, MAX_ALPHA_SIZE, MAX_CODE_LEN, MAX_SELECTORS, N_GROUPS, N_ITERS, NUM_OVERSHOOT_BYTES, rNums, RUNA, RUNB

构造器概要

构造器

构造器和说明
CBZip2InputStream(InputStream in)
CBZip2InputStream(InputStream in, SplittableCompressionCodec.READ_MODE readMode) Constructs a new CBZip2InputStream which decompresses bytes read from the specified stream.

方法概要

方法

限定符和类型	方法和说明
void	close()
long	getProcessedByteCount() This method reports the processed bytes so far.
static long	numberOfBytesTillNextMarker(InputStream in) Returns the number of bytes between the current stream position and the immediate next BZip2 block marker.
int	read()
int	read(byte[] dest, int offs, int len) In CONTINOUS reading mode, this read method starts from the start of the compressed stream and end at the end of file by emitting un-compressed data.
protected void	reportCRCError()
boolean	skipToNextMarker(long marker, int markerBitLength) This method tries to find the marker (passed to it as the first parameter) in the stream.
protected void	updateProcessedByteCount(int count) This method keeps track of raw processed compressed bytes.
void	updateReportedByteCount(int count) This method is called by the client of this class in case there are any corrections in the stream position.

从类继承的方法 java.io.InputStream

available, mark, markSupported, read, reset, skip

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

字段详细资料

BLOCK_DELIMITER

public static final long BLOCK_DELIMITER

另请参阅:

常量字段值

EOS_DELIMITER

public static final long EOS_DELIMITER

另请参阅:

常量字段值

构造器详细资料

CBZip2InputStream

public CBZip2InputStream(InputStream in,
                 SplittableCompressionCodec.READ_MODE readMode)
                  throws IOException

Constructs a new CBZip2InputStream which decompresses bytes read from the specified stream.

Although BZip2 headers are marked with the magic "Bz" this constructor expects the next byte in the stream to be the first one after the magic. Thus callers have to skip the first two bytes. Otherwise this constructor will throw an exception.

抛出:

IOException - if the stream content is malformed or an I/O error occurs.

NullPointerException - if in == null

CBZip2InputStream

public CBZip2InputStream(InputStream in)
                  throws IOException

抛出:

IOException

方法详细资料

getProcessedByteCount

public long getProcessedByteCount()

This method reports the processed bytes so far. Please note that this statistic is only updated on block boundaries and only when the stream is initiated in BYBLOCK mode.

updateProcessedByteCount

protected void updateProcessedByteCount(int count)

This method keeps track of raw processed compressed bytes.

参数:

count - count is the number of bytes to be added to raw processed bytes

updateReportedByteCount

public void updateReportedByteCount(int count)

This method is called by the client of this class in case there are any corrections in the stream position. One common example is when client of this code removes starting BZ characters from the compressed stream.

参数:

count - count bytes are added to the reported bytes

skipToNextMarker

public boolean skipToNextMarker(long marker,
                       int markerBitLength)
                         throws IOException,
                                IllegalArgumentException

This method tries to find the marker (passed to it as the first parameter) in the stream. It can find bit patterns of length <= 63 bits. Specifically this method is used in CBZip2InputStream to find the end of block (EOB) delimiter in the stream, starting from the current position of the stream. If marker is found, the stream position will be right after marker at the end of this call.

参数:

marker - The bit pattern to be found in the stream

markerBitLength - No of bits in the marker

抛出:

IOException

IllegalArgumentException - if marketBitLength is greater than 63

reportCRCError

protected void reportCRCError()
                       throws IOException

抛出:

IOException

numberOfBytesTillNextMarker

public static long numberOfBytesTillNextMarker(InputStream in)
                                        throws IOException

Returns the number of bytes between the current stream position and the immediate next BZip2 block marker.

参数:

in - The InputStream

返回:

long Number of bytes between current stream position and the next BZip2 block start marker.

抛出:

IOException

read

public int read()
         throws IOException

指定者:

read 在类中 InputStream

抛出:

IOException

read

public int read(byte[] dest,
       int offs,
       int len)
         throws IOException

In CONTINOUS reading mode, this read method starts from the start of the compressed stream and end at the end of file by emitting un-compressed data. In this mode stream positioning is not announced and should be ignored. In BYBLOCK reading mode, this read method informs about the end of a BZip2 block by returning EOB. At this event, the compressed stream position is also announced. This announcement tells that how much of the compressed stream has been de-compressed and read out of this class. In between EOB events, the stream position is not updated.

覆盖:

read 在类中 InputStream

返回:

int The return value greater than 0 are the bytes read. A value of -1 means end of stream while -2 represents end of block

抛出:

IOException - if the stream content is malformed or an I/O error occurs.

close

public void close()
           throws IOException

指定者:

close 在接口中 Closeable

指定者:

close 在接口中 AutoCloseable

覆盖:

close 在类中 InputStream

抛出:

IOException