com.helger.mail.datahandler

Class AbstractStreamingDataHandler

java.lang.Object

javax.activation.DataHandler

com.helger.mail.datahandler.AbstractStreamingDataHandler

All Implemented Interfaces:

Transferable, Closeable, AutoCloseable

Direct Known Subclasses:

DataSourceStreamingDataHandler

public abstract class AbstractStreamingDataHandler
extends DataHandler
implements Closeable

DataHandler extended 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, DataHandler 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.
AbstractStreamingDataHandler solves this problem by offering methods that enable faster bulk "consume once" read operation.

Author:

Jitendra Kotamraju, Philip Helger

Constructor Summary

Constructors

Constructor and Description
AbstractStreamingDataHandler(DataSource aDataSource)
AbstractStreamingDataHandler(Object aObj, String sMimeType)
AbstractStreamingDataHandler(URL aUrl)

Method Summary

Modifier and Type	Method and Description
String	getHrefCid()
abstract InputStream	readOnce() Works like DataHandler.getInputStream() except that this method can be invoked only once.
void	setHrefCid(String sHrefCid)

Methods inherited from class javax.activation.DataHandler

getAllCommands, getBean, getCommand, getContent, getContentType, getDataSource, getInputStream, getName, getOutputStream, getPreferredCommands, getTransferData, getTransferDataFlavors, isDataFlavorSupported, setCommandMap, setDataContentHandlerFactory, writeTo

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.io.Closeable

close

Constructor Detail

AbstractStreamingDataHandler

public AbstractStreamingDataHandler(@Nonnull
                                    Object aObj,
                                    @Nonnull
                                    String sMimeType)

AbstractStreamingDataHandler

public AbstractStreamingDataHandler(@Nonnull
                                    URL aUrl)

AbstractStreamingDataHandler

public AbstractStreamingDataHandler(@Nonnull
                                    DataSource aDataSource)

Method Detail

getHrefCid

@Nullable
public String getHrefCid()

setHrefCid

public void setHrefCid(@Nullable
                       String sHrefCid)

readOnce

@Nonnull
public abstract InputStream readOnce()
                                        throws IOException

Works like DataHandler.getInputStream() except that this method can be invoked only once.
This is used as a signal from the caller that there will be no further DataHandler.getInputStream() invocation nor readOnce() invocation on this object (which would result in IOException.)
When 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 DataHandler.getInputStream() multiple times and then call readOnce() afterward. Streams created such a way can be read in any order - there's no requirement that streams created earlier must be read first.

Returns:

always non-null. Represents the content of this BLOB. The returned stream is generally not buffered, so for better performance read in a big batch or wrap this into BufferedInputStream.

Throws:

IOException - if any i/o error