public abstract class StreamingDataHandler extends DataHandler implements Closeable
DataHandlerextended to offer better buffer management in a streaming environment.
DataHandler is used commonly as a data format across
multiple systems (such as JAXB/WS.) Unfortunately,
has the semantics of "read as many times as you want", so this makes
it difficult for involving parties to handle a BLOB in a streaming fashion.
StreamingDataHandler solves this problem by offering methods
that enable faster bulk "consume once" read operation.
|Constructor and Description|
|Modifier and Type||Method and Description|
Releases any resources associated with this DataHandler.
Obtains the BLOB into a specified file.
getAllCommands, getBean, getCommand, getContent, getContentType, getDataSource, getInputStream, getName, getOutputStream, getPreferredCommands, getTransferData, getTransferDataFlavors, isDataFlavorSupported, setCommandMap, setDataContentHandlerFactory, writeTo
public StreamingDataHandler(URL url)
public StreamingDataHandler(DataSource dataSource)
public abstract InputStream readOnce() throws IOException
DataHandler.getInputStream()except that this method can be invoked only once.
DataHandler is backed by a streaming BLOB
(such as an attachment in a web service read from the network),
this allows the callee to avoid unnecessary buffering.
Note that it is legal to call
multiple times and then call
Streams created such a way can be read in any order —
there's no requirement that streams created earlier must be read
public abstract void moveTo(File dst) throws IOException
Semantically, this method is roughly equivalent to the following code, except that the actual implementation is likely to be a lot faster.
InputStream i = getInputStream(); OutputStream o = new FileOutputStream(dst); int ch; while((ch=i.read())!=-1) o.write(ch); i.close(); o.close();
The main motivation behind this method is that often
DataHandler that reads data from a streaming source
will use a temporary file as a data store to hold data
(think of commons-fileupload.) In such case this method
can be as fast as calling
This method shouldn't be called when there are any open streams.
After this method is invoked,
DataHandler.getInputStream() will simply open the destination
file you've specified as an argument. So if you further
move the file or delete this file, those methods will
behave in undefined fashion. For a simliar reason,
calling this method multiple times will cause
public abstract void close() throws IOException
public String getHrefCid()
public void setHrefCid(String cid)
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