com.microsoft.azure.storage.blob

Class BlobInputStream

java.lang.Object

java.io.InputStream

com.microsoft.azure.storage.blob.BlobInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public final class BlobInputStream
extends InputStream

Provides an input stream to read a given blob resource.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BlobInputStream(CloudBlob parentBlob, AccessCondition accessCondition, BlobRequestOptions options, OperationContext opContext) Initializes a new instance of the BlobInputStream 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.
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.lang.Object

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

Constructor Detail

BlobInputStream

@DoesServiceRequest
protected BlobInputStream(CloudBlob parentBlob,
                                              AccessCondition accessCondition,
                                              BlobRequestOptions options,
                                              OperationContext opContext)
                                       throws StorageException

Initializes a new instance of the BlobInputStream class.

Parameters:

parentBlob - A CloudBlob object which represents the blob that this stream is associated with.

accessCondition - An AccessCondition object which represents the access conditions for the blob.

options - A BlobRequestOptions object which represents that specifies any additional options for the request.

opContext - An OperationContext object which is used to track the execution of the operation.

Throws:

StorageException - An exception representing any error which occurred during the operation.

Method Detail

available

public int available()
              throws IOException

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.

Throws:

IOException - If an I/O error occurs.

close

public void close()
           throws IOException

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

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

@DoesServiceRequest
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:

IOException - If an I/O error occurs.

read

@DoesServiceRequest
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

@DoesServiceRequest
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()
           throws IOException

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:

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

skip

public long skip(long n)
          throws IOException

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.

Throws:

IOException