[dev] question about use XStorage in filter

[cokecola13574]

Hello! 
  I'm chensuchun.I'm a newbie in devloping filter.I implement a filter for 
exporting and importing my own format file,whose format is based on odt.But I 
get some problems about filter.
the code of &nbsp;function filter( const Sequence< PropertyValue >& rDescriptor 
) is following:
xDoc = uno::Reference< document::XStorageBasedDocument >( mxSrcDoc, 
uno::UNO_QUERY );&nbsp; ///mxSrcDoc is set by setSourceDocument()
////save&nbsp;to a tmp storage use filter writer8
&nbsp;&nbsp;xSourceStorage = uno::Reference< embed::XStorage >( 
xStorageFactory->createInstance(),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 uno::UNO_QUERY );
&nbsp;&nbsp;uno::Sequence< beans::PropertyValue > afArgs( 1 );
&nbsp;&nbsp;afArgs[0].Name = ::rtl::OUString::createFromAscii( "FilterName" );
&nbsp;&nbsp;afArgs[0].Value <<= ::rtl::OUString::createFromAscii( "writer8" );
&nbsp;&nbsp;xDoc->storeToStorage( xSourceStorage, afArgs );
////add a sub storage to the&nbsp;&nbsp;xSourceStorage 
const ::rtl::OUString aSubStorageName ( RTL_CONSTASCII_USTRINGPARAM ( 
"SubStorage" ) );
&nbsp;&nbsp;&nbsp;uno::Reference< embed::XStorage > xSubStorage = 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;xSourceStorage->openStorageElement(
 aSubStorageName, embed::ElementModes::WRITE );
uno::Reference< beans::XPropertySet > xSubStoagePro( xSubStorage, 
uno::UNO_QUERY );
&nbsp;&nbsp;&nbsp;xSubStoagePro->setPropertyValue( 
OUString::createFromAscii("MediaType"), 
makeAny(OUString::createFromAscii("SubMediaType")) );
......
///create the target storage
uno::Sequence< uno::Any > aArgs( 2 );
&nbsp;aArgs[0] <<= aURL; ////get from rDescriptor&nbsp;
&nbsp;aArgs[1] <<= embed::ElementModes::READWRITE;
&nbsp;uno::Reference< embed::XStorage > xTargetStorage( 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;xStorageFactory->createInstanceWithArguments(
 aArgs ),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
 uno::UNO_QUERY );

////copy to target storage and commit
xSourceStorage->copyToStorage( xTargetStorage );
&nbsp;&nbsp;&nbsp;bRet = sal_True;
&nbsp;&nbsp;&nbsp;uno::Reference< XTransactedObject > xTransaction = 
&nbsp;&nbsp;&nbsp;&nbsp;uno::Reference< XTransactedObject >( xTargetStorage, 
UNO_QUERY );
&nbsp;&nbsp;&nbsp;if( xTransaction.is() )
&nbsp;&nbsp;&nbsp;&nbsp;xTransaction->commit();
/////dispose them
uno::Reference< lang::XComponent > xComponent1( xSourceStorage, uno::UNO_QUERY 
);
&nbsp;&nbsp;&nbsp;OSL_ENSURE( !xSourceStorage.is() || xComponent1.is(), "Wrong 
storage implementation!" );
&nbsp;&nbsp;&nbsp;if ( xComponent1.is() )
&nbsp;&nbsp;&nbsp;&nbsp;xComponent1->dispose();
&nbsp;&nbsp;&nbsp;uno::Reference< lang::XComponent > xComponent2( 
xTargetStorage, uno::UNO_QUERY );
&nbsp;&nbsp;&nbsp;OSL_ENSURE( !xTargetStorage.is() || xComponent2.is(), "Wrong 
storage implementation!" );
&nbsp;&nbsp;&nbsp;if ( xComponent2.is() )
&nbsp;&nbsp;&nbsp;&nbsp;xComponent2->dispose();
////End
After the execution of filter( const Sequence< PropertyValue >& rDescriptor ),
the target file is created and the size of the file is about 7K.
But after&nbsp; executing the following code in sal_Bool 
SfxObjectShell::SaveTo_Impl:

&nbsp;&nbsp;// transfer data to its destinated location
&nbsp;&nbsp;// the medium commits the storage or the stream it is based on
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; RegisterTransfer( rMedium );
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; bOk = rMedium.Commit();
the target file becomes 0K.
Why?&nbsp;
Is some thing wrong in my filter( const Sequence< PropertyValue >& rDescriptor 
) function?
what should I do with the XStorage ?&nbsp;
Any help and sugestion in identifying the missing pieces is appreciated.
Thanks &nbsp;&nbsp;

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