com.google.common.io

Class FileBackedOutputStream

java.lang.Object

java.io.OutputStream

com.google.common.io.FileBackedOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

@Beta
 @GwtIncompatible
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.

When this stream creates a temporary file, it restricts the file's permissions to the current user or, in the case of Android, the current app. If that is not possible (as is the case under the very old Android Ice Cream Sandwich release), then this stream throws an exception instead of creating a file that would be more accessible. (This behavior is new in Guava 32.0.0. Previous versions would create a file that is more accessible, as discussed in Guava issue 2575. TODO: b/283778848 - Fill in CVE number once it's available.)

This class is thread-safe.

Since:

1.0

Author:

Chris Nokleberg

Constructor Summary

Constructors

Constructor and 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 and 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.lang.Object

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

Constructor Detail

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

Throws:

IllegalArgumentException - if fileThreshold is negative

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

Throws:

IllegalArgumentException - if fileThreshold is negative

Method Detail

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 Closeable

Specified by:

close in interface AutoCloseable

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