Package net.sf.basedb.util

Class StreamCacher

java.lang.Object

net.sf.basedb.util.StreamCacher

All Implemented Interfaces:

AutoCloseable

public class StreamCacher
extends Object
implements AutoCloseable

Caches the contents of a stream to a local temporary file. The getNewStream() method will create a stream that appears to be reading from the start of the master stream, except that it will read cached data to begin with and continue with the master stream only if needed.

This class is useful when you know (or suspect) that you need to read the same stream multiple times, but the stream may be "expensive" to retrieve, either in terms of network capacity or cpu processing.

Since:

2.16

Author:

Nicklas

See Also:

• File.getCachedDownloadStream()

Last modified

$Date: 2018-12-12 15:41:10 +0100 (on, 12 dec 2018) $

Field Summary

Fields

Modifier and Type	Field	Description
private final File	cacheFile
private final OutputStream	cacheOut
private final InputStream	master
private final InputStream	splitter

Constructor Summary

Constructors

Constructor	Description
StreamCacher(InputStream master)	Create a new stream cacher for reading from the given master stream.
StreamCacher(InputStream master, File cacheFile)	Create a new stream cacher for reading from the given master stream.

Method Summary

Modifier and Type	Method	Description
void	close()	Close the master stream and remove the cached file data.
InputStream	getNewStream()	Get a new stream that appears to be reading from the start of the master stream.

Methods inherited from class java.lang.Object

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

Field Details

master

private final InputStream master

splitter

private final InputStream splitter

cacheFile

private final File cacheFile

cacheOut

private final OutputStream cacheOut

Constructor Details

StreamCacher

public StreamCacher(InputStream master)
             throws IOException

Create a new stream cacher for reading from the given master stream.

Parameters:

master - The master input stream

Throws:

IOException

StreamCacher

public StreamCacher(InputStream master,
 File cacheFile)
             throws IOException

Create a new stream cacher for reading from the given master stream.

Parameters:

master - The master input stream

cacheFile - Use this file for the cached data, if the file already exist it will be overwritten, if this parameter is null a random file will be created in the default temporary directory

Throws:

IOException

Method Details

close

public void close()

Close the master stream and remove the cached file data.

Specified by:

close in interface AutoCloseable

getNewStream

public InputStream getNewStream()
                         throws IOException

Get a new stream that appears to be reading from the start of the master stream. The new stream will read cached data (if any), and only when the end of that data is reached it will start reading from the master stream. The data from the master stream is automatically copied to the cache.

Returns:

An Input stream

Throws:

IOException