interface XInputStream in module com::sun::star::io::

(Global Index)

Syntax

interface XInputStream : com::sun::star::uno::XInterface ;

Description

This is the basic interface to read data from a stream.

See the streaming document for further information on chaining and piping streams.

Method Summary

readBytes reads the specified number of bytes in the given sequence.

readSomeBytes reads the available number of bytes at maximum nMaxBytesToRead .

skipBytes skips the next nBytesToSkip bytes (must be positive).

available states how many bytes can be read or skipped without blocking.

closeInput closes the stream.

Known Services Which Export this Interface

com::sun::star::io::MarkableInputStream

com::sun::star::io::Pipe

com::sun::star::io::MarkableInputStream

com::sun::star::io::Pipe

Method Details



readBytes

Syntax

long readBytes (
sequence< byte > aData,
long nBytesToRead )
raises ( com::sun::star::io::NotConnectedException , com::sun::star::io::BufferSizeExceededException , com::sun::star::io::IOException );

Description

reads the specified number of bytes in the given sequence.

The return value specifies the number of bytes which have been put into the sequence. A difference between nBytesToRead and the return value indicates that EOF has been reached. This means that the method blocks until the specified number of bytes are available or the EOF is reached.

Parameter aData

after the call, the byte sequence contains the requested number of bytes (or less as a sign of EOF).

C++ only : Note that for unbridged (e.g., in-process) calls, using the same sequence for repetive readBytes()-calls can bear a performance advantage. The callee can put the data directly into the sequence so that no buffer reallocation is necessary. But this holds only when

  1. neither caller nor callee keep a second reference to the same sequence.
  2. the sequence is pre-allocated with the requested number of bytes.
  3. the same sequence is reused ( simply preallocationg a new sequence for every call bears no advantage ).
  4. the call is not bridged (e.g., betweeen different compilers or different processes ).
If the same 'optimized' code runs against an interface in a different process, there is an unnecessary memory allocation/deallocation (the out parameter is of course NOT transported over the connection), but this should be negligible compared to a synchron call.

readSomeBytes

Syntax

long readSomeBytes (
sequence< byte > aData,
long nMaxBytesToRead )
raises ( com::sun::star::io::NotConnectedException , com::sun::star::io::BufferSizeExceededException , com::sun::star::io::IOException );

Description

reads the available number of bytes at maximum nMaxBytesToRead .

This method blocks the thread until at least one byte is available.


skipBytes

Syntax

void skipBytes (
long nBytesToSkip )
raises ( com::sun::star::io::NotConnectedException , com::sun::star::io::BufferSizeExceededException , com::sun::star::io::IOException );

Description

skips the next nBytesToSkip bytes (must be positive).

It is up to the implementation whether this method is blocking the thread or not.


available

Syntax

long available ();
raises ( com::sun::star::io::NotConnectedException , com::sun::star::io::IOException );

Description

states how many bytes can be read or skipped without blocking.

Note: This method offers no information on whether the EOF has been reached.


closeInput

Syntax

void closeInput ();
raises ( com::sun::star::io::NotConnectedException , com::sun::star::io::IOException );

Description

closes the stream.

Users must close the stream explicitly when no further reading should be done. (There may exist ring references to chained objects that can only be released during this call. Thus not calling this method would result in a leak of memory or external resources.)

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