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
AnOutputStream
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 passingfalse
in the second parameter.
This class is thread-safe.
- Since:
- 1.0
- Author:
- Chris Nokleberg
-
-
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 theByteSource
returned byasByteSource()
is finalized.FileBackedOutputStream(int fileThreshold, boolean resetOnFinalize)
Creates a new instance that uses the given file threshold, and optionally resets the data when theByteSource
returned byasByteSource()
is finalized.
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description ByteSource
asByteSource()
Returns a readableByteSource
view of the data that has been written to this stream.void
close()
Closes this output stream and releases any system resources associated with this stream.void
flush()
Flushes this output stream and forces any buffered output bytes to be written out.void
reset()
Callsclose()
if not already closed, and then resets this object back to its initial state, for reuse.void
write(byte[] b)
Writesb.length
bytes from the specified byte array to this output stream.void
write(byte[] b, int off, int len)
Writeslen
bytes from the specified byte array starting at offsetoff
to this output stream.void
write(int b)
Writes the specified byte to this output stream.-
Methods inherited from class java.io.OutputStream
nullOutputStream
-
-
-
-
Constructor Detail
-
FileBackedOutputStream
public FileBackedOutputStream(int fileThreshold)
Creates a new instance that uses the given file threshold, and does not reset the data when theByteSource
returned byasByteSource()
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 theByteSource
returned byasByteSource()
is finalized.- Parameters:
fileThreshold
- the number of bytes before the stream should switch to buffering to a fileresetOnFinalize
- if true, thereset()
method will be called when theByteSource
returned byasByteSource()
is finalized.
-
-
Method Detail
-
asByteSource
public ByteSource asByteSource()
Returns a readableByteSource
view of the data that has been written to this stream.- Since:
- 15.0
-
reset
public void reset() throws IOException
Callsclose()
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
Description copied from class:java.io.OutputStream
Writes the specified byte to this output stream. The general contract forwrite
is that one byte is written to the output stream. The byte to be written is the eight low-order bits of the argumentb
. The 24 high-order bits ofb
are ignored.Subclasses of
OutputStream
must provide an implementation for this method.- Specified by:
write
in classOutputStream
- Parameters:
b
- thebyte
.- Throws:
IOException
- if an I/O error occurs. In particular, anIOException
may be thrown if the output stream has been closed.
-
write
public void write(byte[] b) throws IOException
Description copied from class:java.io.OutputStream
Writesb.length
bytes from the specified byte array to this output stream. The general contract forwrite(b)
is that it should have exactly the same effect as the callwrite(b, 0, b.length)
.- Overrides:
write
in classOutputStream
- Parameters:
b
- the data.- Throws:
IOException
- if an I/O error occurs.- See Also:
OutputStream.write(byte[], int, int)
-
write
public void write(byte[] b, int off, int len) throws IOException
Description copied from class:java.io.OutputStream
Writeslen
bytes from the specified byte array starting at offsetoff
to this output stream. The general contract forwrite(b, off, len)
is that some of the bytes in the arrayb
are written to the output stream in order; elementb[off]
is the first byte written andb[off+len-1]
is the last byte written by this operation.The
write
method ofOutputStream
calls the write method of one argument on each of the bytes to be written out. Subclasses are encouraged to override this method and provide a more efficient implementation.If
b
isnull
, aNullPointerException
is thrown.If
off
is negative, orlen
is negative, oroff+len
is greater than the length of the arrayb
, then anIndexOutOfBoundsException
is thrown.- Overrides:
write
in classOutputStream
- Parameters:
b
- the data.off
- the start offset in the data.len
- the number of bytes to write.- Throws:
IOException
- if an I/O error occurs. In particular, anIOException
is thrown if the output stream is closed.
-
close
public void close() throws IOException
Description copied from class:java.io.OutputStream
Closes this output stream and releases any system resources associated with this stream. The general contract ofclose
is that it closes the output stream. A closed stream cannot perform output operations and cannot be reopened.The
close
method ofOutputStream
does nothing.- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classOutputStream
- Throws:
IOException
- if an I/O error occurs.
-
flush
public void flush() throws IOException
Description copied from class:java.io.OutputStream
Flushes this output stream and forces any buffered output bytes to be written out. The general contract offlush
is that calling it is an indication that, if any bytes previously written have been buffered by the implementation of the output stream, such bytes should immediately be written to their intended destination.If the intended destination of this stream is an abstraction provided by the underlying operating system, for example a file, then flushing the stream guarantees only that bytes previously written to the stream are passed to the operating system for writing; it does not guarantee that they are actually written to a physical device such as a disk drive.
The
flush
method ofOutputStream
does nothing.- Specified by:
flush
in interfaceFlushable
- Overrides:
flush
in classOutputStream
- Throws:
IOException
- if an I/O error occurs.
-
-