StorageInputStream Class

Package:

com.azure.storage.common

Maven Artifact:

com.azure:azure-storage-common:12.25.0

• java.lang.Object
• • java.io.InputStream
  • • com.azure.storage.common.StorageInputStream

public abstract class StorageInputStream
extends InputStream

Provides an input stream to read a given storage resource.

Field Summary

Modifier and Type	Field and Description
protected int	bufferSize Holds the length of the current buffer in bytes.
protected long	bufferStartOffset Holds the absolute byte position of the start of the current buffer.
protected IOException	lastError Holds the last exception this stream encountered.
protected volatile boolean	streamFaulted A flag to determine if the stream is faulted, if so the last error will be thrown on next operation.

Constructor Summary

Modifier	Constructor	Description
protected	StorageInputStream(int chunkSize, long contentLength)	Initializes a new instance of the StorageInputStream class.
protected	StorageInputStream(long rangeOffset, Long rangeLength, int chunkSize, long contentLength)	Initializes a new instance of the StorageInputStream class.
protected	StorageInputStream(long rangeOffset, Long rangeLength, int chunkSize, long contentLength, ByteBuffer initialBuffer)	Initializes a new instance of the StorageInputStream class.

Method Summary

Modifier and Type	Method and Description
synchronized int	available() Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.
synchronized void	close() Closes this input stream and releases any system resources associated with the stream.
protected abstract ByteBuffer	dispatchRead(int readLength, long offset) Dispatches a read operation of N bytes and updates stream state accordingly.
synchronized void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the mark and reset methods.
int	read() Reads the next byte of data from the input stream.
int	read(byte[] b) Reads some number of bytes from the input stream and stores them into the buffer array b.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
synchronized void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
synchronized long	skip(long n) Skips over and discards n bytes of data from this input stream.

Methods inherited from java.io.InputStream

available close mark markSupported nullInputStream read read read readAllBytes readNBytes readNBytes reset skip transferTo

Methods inherited from java.lang.Object

clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

Field Details

bufferSize

protected int bufferSize

Holds the length of the current buffer in bytes.

bufferStartOffset

protected long bufferStartOffset

Holds the absolute byte position of the start of the current buffer.

lastError

protected IOException lastError

Holds the last exception this stream encountered.

streamFaulted

protected volatile boolean streamFaulted

A flag to determine if the stream is faulted, if so the last error will be thrown on next operation.

Constructor Details

StorageInputStream

protected StorageInputStream(int chunkSize, long contentLength)

Initializes a new instance of the StorageInputStream class.

Parameters:

chunkSize - the size of chunk allowed to pass for storage service request.

contentLength - the actual content length for input data.

StorageInputStream

protected StorageInputStream(long rangeOffset, Long rangeLength, int chunkSize, long contentLength)

Initializes a new instance of the StorageInputStream class.

Parameters:

rangeOffset - The offset of the data to begin stream.

rangeLength - How much data the stream should return after blobRangeOffset.

chunkSize - Holds the stream read size.

contentLength - The length of the stream to be transferred.

StorageInputStream

protected StorageInputStream(long rangeOffset, Long rangeLength, int chunkSize, long contentLength, ByteBuffer initialBuffer)

Initializes a new instance of the StorageInputStream class.

Parameters:

rangeOffset - The offset of the data to begin stream.

rangeLength - How much data the stream should return after blobRangeOffset.

chunkSize - Holds the stream read size.

contentLength - The length of the stream to be transferred.

initialBuffer - The first chunk of the download. Fetched alongside properties for optimization

Method Details

available

public synchronized int available()

Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream. The next invocation might be the same thread or another thread. A single read or skip of this many bytes will not block, but may read or skip fewer bytes.

Overrides:

StorageInputStream.available()

Returns:

An int which represents an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking, or 0 when it reaches the end of the input stream.

close

public synchronized void close()

Closes this input stream and releases any system resources associated with the stream.

Overrides:

StorageInputStream.close()

dispatchRead

protected abstract ByteBuffer dispatchRead(int readLength, long offset)

Dispatches a read operation of N bytes and updates stream state accordingly.

Parameters:

readLength - An int which represents the number of bytes to read.

offset - The start point of data to be acquired.

Returns:

The bytebuffer which store one chunk size of data.

Throws:

IOException

- If an I/O error occurs.

mark

public synchronized void mark(int readlimit)

Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.

Overrides:

StorageInputStream.mark(int readlimit)

Parameters:

readlimit - An int which represents the maximum limit of bytes that can be read before the mark position becomes invalid.

markSupported

public boolean markSupported()

Tests if this input stream supports the mark and reset methods. Whether mark and reset are supported is an invariant property of a particular input stream instance. The markSupported method of InputStream returns false.

Overrides:

StorageInputStream.markSupported()

Returns:

True if this stream instance supports the mark and reset methods; False otherwise.

read

public int read()

Reads the next byte of data from the input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

Overrides:

StorageInputStream.read()

Returns:

An int which represents the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException

- when no available bytes to read.

read

public int read(byte[] b)

Reads some number of bytes from the input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown. If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at the end of the file, the value -1 is returned; otherwise, at least one byte is read and stored into b. The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected. The read(b) method for class InputStream has the same effect as: read(b, 0, b.length)

Overrides:

StorageInputStream.read(byte[] b)

Parameters:

b - A byte array which represents the buffer into which the data is read.

Throws:

IOException

- If the first byte cannot be read for any reason other than the end of the file, if the input stream has been closed, or if some other I/O error occurs.

read

public int read(byte[] b, int off, int len)

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown. If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b. The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected. In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected. The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. The default implementation of this method blocks until the requested amount of input data len has been read, end of file is detected, or an exception is thrown. Subclasses are encouraged to provide a more efficient implementation of this method.

Overrides:

StorageInputStream.read(byte[] b, int off, int len)

Parameters:

b - A byte array which represents the buffer into which the data is read.

off - An int which represents the start offset in the byte array at which the data is written.

len - An int which represents the maximum number of bytes to read.

Returns:

An int which represents the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException

- If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.

reset

public synchronized void reset()

Repositions this stream to the position at the time the mark method was last called on this input stream. Note repositioning the blob read stream will disable blob MD5 checking.

Overrides:

StorageInputStream.reset()

skip

public synchronized long skip(long n)

Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped. Note repositioning the blob read stream will disable blob MD5 checking.

Overrides:

StorageInputStream.skip(long n)

Parameters:

n - A long which represents the number of bytes to skip.