Module com.google.common

Package com.google.common.io

Class FileBackedOutputStream

java.lang.Object

java.io.OutputStream

com.google.common.io.FileBackedOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

@Beta
public final class FileBackedOutputStream
extends OutputStream

An OutputStream that starts buffering to a byte array, but switches to file buffering once the data reaches a configurable size.

Temporary files created by this stream may live in the local filesystem until either:

• reset() is called (removing the data in this stream and deleting the file), or...
• this stream (or, more precisely, its asByteSource() view) is finalized during garbage collection, AND this stream was not constructed with the 1-arg constructor or the 2-arg constructor passing false in the second parameter.

This class is thread-safe.

Since:

1.0

Constructor Summary

Constructors

Constructor	Description
FileBackedOutputStream(int fileThreshold)	Creates a new instance that uses the given file threshold, and does not reset the data when the ByteSource returned by asByteSource() is finalized.
FileBackedOutputStream(int fileThreshold, boolean resetOnFinalize)	Creates a new instance that uses the given file threshold, and optionally resets the data when the ByteSource returned by asByteSource() is finalized.

Method Summary

Modifier and Type	Method	Description
ByteSource	asByteSource()	Returns a readable ByteSource view of the data that has been written to this stream.
void	close()
void	flush()
void	reset()	Calls close() if not already closed, and then resets this object back to its initial state, for reuse.
void	write(byte[] b)
void	write(byte[] b, int off, int len)
void	write(int b)

Methods inherited from class java.io.OutputStream

nullOutputStream

Methods inherited from class java.lang.Object

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

Constructor Details

FileBackedOutputStream

public FileBackedOutputStream(int fileThreshold)

Creates a new instance that uses the given file threshold, and does not reset the data when the ByteSource returned by asByteSource() is finalized.

Parameters:

fileThreshold - the number of bytes before the stream should switch to buffering to a file

FileBackedOutputStream

public FileBackedOutputStream(int fileThreshold,
 boolean resetOnFinalize)

Creates a new instance that uses the given file threshold, and optionally resets the data when the ByteSource returned by asByteSource() is finalized.

Parameters:

fileThreshold - the number of bytes before the stream should switch to buffering to a file

resetOnFinalize - if true, the reset() method will be called when the ByteSource returned by asByteSource() is finalized.

Method Details

asByteSource

public ByteSource asByteSource()

Returns a readable ByteSource view of the data that has been written to this stream.

Since:

15.0

reset

public void reset()
           throws IOException

Calls close() if not already closed, and then resets this object back to its initial state, for reuse. If data was buffered to a file, it will be deleted.

Throws:

IOException - if an I/O error occurred while deleting the file buffer

write

public void write(int b)
           throws IOException

Specified by:

write in class OutputStream

Throws:

IOException

write

public void write(byte[] b)
           throws IOException

Overrides:

write in class OutputStream

Throws:

IOException

write

public void write(byte[] b,
 int off,
 int len)
           throws IOException

Overrides:

write in class OutputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Overrides:

close in class OutputStream

Throws:

IOException

flush

public void flush()
           throws IOException

Specified by:

flush in interface Flushable

Overrides:

flush in class OutputStream

Throws:

IOException