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nsISupports
Last changed in Gecko 1.0 Un flux de sortie peut être «bloquant» ou «non-bloquant" (voir le IsNonBlocking()
méthode). Un flux de sortie bloquant peut suspendre le thread appelant afin de satisfaire un appel à Close()
, Flush()
, write()
, writeFrom()
, ou writeSegments()
. Un flux de sortie non-bloquant, d'autre part, ne bloque pas l'exécution du thread appelant .
Méthode
void close(); |
void flush(); |
boolean isNonBlocking(); |
unsigned long write(in string aBuf, in unsigned long aCount); |
unsigned long writeFrom(in nsIInputStream aFromStream, in unsigned long aCount); |
unsigned long writeSegments(in nsReadSegmentFun aReader, in voidPtr aClosure, in unsigned long aCount); Native code only! |
Methods
close()
Close the stream. Forces the output stream to flush()
any buffered data.
void close();
Parameters
None.
Exceptions thrown
NS_BASE_STREAM_WOULD_BLOCK
- Indicates that closing the output stream would block the calling thread for an indeterminate amount of time. This exception may only be thrown if
isNonBlocking()
returns true.
flush()
Cette méthode peut être appelée pour demander le flux de sortie pour écrire le contenu de tous les tampons internes à un collecteur de données de bas niveau, comme un fichier sur le disque. Cependant, la méthode flush peut tout simplement ne rien faire en fonction de la mise en œuvre du flux de sortie.
void flush();
Parameters
None.
Exceptions thrown
NS_BASE_STREAM_WOULD_BLOCK
- Indicates that flushing the output stream would block the calling thread for an indeterminate amount of time. This exception may only be thrown if
isNonBlocking()
returns true.
isNonBlocking()
nsIAsyncOutputStream
to provide consumers with a way to wait for the stream to accept more data once its write()
method is unable to accept any data without blocking.boolean isNonBlocking();
Parameters
None.
Return value
true
if stream is non-blocking.
Exceptions thrown
NS_BASE_STREAM_WOULD_BLOCK
- A non-blocking stream may throw this exception when written to if space for the data is not immediately available.
write()
Cette méthode copies des données à partir d'un tampon dans le flux.
unsigned long write( in string aBuf, in unsigned long aCount );
Parameters
aBuf
- The buffer containing the data to be written.
aCount
- The size of the buffer, or the maximum number of bytes to copy from the buffer.
Return value
This method returns the number of bytes copied from the buffer (may be less than aCount).
Exceptions thrown
NS_BASE_STREAM_WOULD_BLOCK
- If writing to the output stream would block the calling thread (non-blocking mode only)
writeFrom()
Cette méthode copies des données à partir d'une nsIInputStream
à notre nsIOutputStream
.
A nsIOutputStream
is not required to implement this method. In some contexts, writeFrom
may be guaranteed to be implemented, but in general it is not. This method serves as an optimization.
Write()
method.unsigned long writeFrom( in nsIInputStream aFromStream, in unsigned long aCount );
Parameters
aFromStream
- An
nsIInputStream
containing the data to be written. aCount
- The maximum number of bytes to write to the stream.
Return value
This method returns the number of bytes written to the stream (may be less than aCount).
Exceptions thrown
NS_BASE_STREAM_WOULD_BLOCK
- Indicates that writing to the output stream would block the calling thread for an indeterminate amount of time. This exception may only be thrown if
isNonBlocking()
returns true. NS_ERROR_NOT_IMPLEMENTED
- Indicates that the stream does not implement this method. Typically, output streams that do not have an internal buffer will not implement this method since such an implementation would require an intermediate buffer unless
aFromStream
supportednsIInputStream.readSegments()
, but that is not guaranteed.
writeSegments
Méthode d'écriture de bas niveau qui a accès à un tampon sous-jacente du flux. La fonction de lecteur peut être appelée plusieurs fois pour les tampons segmentés. Cette méthode devrait continuer à appeler le lecteur jusqu'à ce qu'il n'y a plus rien à écrire ou le lecteur renvoie une erreur. Cette méthode ne devrait pas appeler le lecteur avec zéro octets à fournir.
nsIOutputStream
is not required to implement this method. In some contexts, writeSegments
may be guaranteed to be implemented, but in general it is not. This method serves as an optimization.unsigned long writeSegments( in nsReadSegmentFun aReader, in voidPtr aClosure, in unsigned long aCount );
Parameters
aReader
- A callback function that may be called multiple times. See
nsReadSegmentFun
for more details on this function. aClosure
- A parameter that is passed to aReader each time it is called.
aCount
- The maximum number of bytes to write to the stream.
Return value
This method returns the number of bytes written to the stream (may be less than aCount).
Exceptions thrown
NS_BASE_STREAM_WOULD_BLOCK
- Indicates that writing to the output stream would block the calling thread for an indeterminate amount of time. This exception may only be thrown if
isNonBlocking()
returns true. NS_ERROR_NOT_IMPLEMENTED
- Indicates that the stream does not have an internal buffer that can be written to directly.
Example
writeSegments()
example
// Copy data from a string to a stream static NS_METHOD CopySegment(nsIInputStream* aStream, void* aClosure, char* aToSegment, PRUint32 aFromOffset, PRUint32 aCount, PRUint32* aReadCount) { // aFromSegment now contains aCount bytes of data. nsACString* pBuf = (nsACString*) aClosure; const char* data; PRUint32 len = NS_CStringGetData(&data); data += aFromOffset; len -= aFromOffset; if (len > aCount) len = aCount; memcpy(aToSegment, data, len); // Indicate that we have copied len bytes to the segment *aReadCount = len; return NS_OK; } // Write the contents of aSource into aStream, using WriteSegments // to avoid intermediate buffer copies. nsresult WriteStream(const nsACString& aSource, nsIInputStream* aStream) { PRUint32 num; return aStream->WriteSegments(CopySegment, (void*) &aSource, aSource.Length(), &num); }
Remarks
This interface was frozen for Gecko 1.0. See bug 124465 for details. From Gecko 2.0 interfaces are no longer frozen.