com.azure.storage.common

Class StorageInputStream

java.lang.Object

java.io.InputStream

com.azure.storage.common.StorageInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public abstract class StorageInputStream
extends InputStream

Provides an input stream to read a given storage resource.

Field Summary

Fields

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

Constructor Summary

Constructors

Modifier	Constructor and 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.

Method Summary

Modifier and Type	Method and Description
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.
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.
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.
void	reset() Repositions this stream to the position at the time the mark method was last called on this input stream.
long	skip(long n) Skips over and discards n bytes of data from this input stream.

Methods inherited from class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo

Methods inherited from class java.lang.Object

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

Field Detail

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.

lastError

protected IOException lastError

Holds the last exception this stream encountered.

bufferStartOffset

protected long bufferStartOffset

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

bufferSize

protected int bufferSize

Holds the length of the current buffer in bytes.

Constructor Detail

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.

Throws:

IndexOutOfBoundsException - when range offset is less than 0 or rangeLength exists but les than or equal to 0.

Method Detail

available

public 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:

available in class InputStream

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 void close()

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

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class InputStream

dispatchRead

protected abstract ByteBuffer dispatchRead(int readLength,
                                           long offset)
                                    throws IOException

Dispatches a read operation of N bytes.

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 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:

mark in class InputStream

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 or not mark and reset are supported is an invariant property of a particular input stream instance. The markSupported method of InputStream returns false.

Overrides:

markSupported in class InputStream

Returns:

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

read

public int read()
         throws IOException

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.

Specified by:

read in class InputStream

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:

RuntimeException - when no available bytes to read.

IOException - If an I/O error occurs.

read

public int read(byte[] b)
         throws IOException

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:

read in class InputStream

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.

NullPointerException - If the byte array b is null.

read

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

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:

read in class InputStream

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.

NullPointerException - If the byte array b is null.

IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off.

reset

public 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:

reset in class InputStream

Throws:

RuntimeException - If this stream has not been marked or if the mark has been invalidated.

skip

public 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:

skip in class InputStream

Parameters:

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