Package org.apache.commons.io.output
Class DeferredFileOutputStream
- java.lang.Object
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- java.io.OutputStream
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- org.apache.commons.io.output.ThresholdingOutputStream
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- org.apache.commons.io.output.DeferredFileOutputStream
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- All Implemented Interfaces:
Closeable
,Flushable
,AutoCloseable
public class DeferredFileOutputStream extends ThresholdingOutputStream
An output stream which will retain data in memory until a specified threshold is reached, and only then commit it to disk. If the stream is closed before the threshold is reached, the data will not be written to disk at all.This class originated in FileUpload processing. In this use case, you do not know in advance the size of the file being uploaded. If the file is small you want to store it in memory (for speed), but if the file is large you want to store it to file (to avoid memory issues).
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Constructor Summary
Constructors Constructor Description DeferredFileOutputStream(int threshold, int initialBufferSize, File outputFile)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point.DeferredFileOutputStream(int threshold, int initialBufferSize, String prefix, String suffix, File directory)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a temporary file beyond that point.DeferredFileOutputStream(int threshold, File outputFile)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point.DeferredFileOutputStream(int threshold, String prefix, String suffix, File directory)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a temporary file beyond that point.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
close()
Closes underlying output stream, and mark this as closedbyte[]
getData()
Returns the data for this output stream as an array of bytes, assuming that the data has been retained in memory.File
getFile()
Returns either the output file specified in the constructor or the temporary file created or null.boolean
isInMemory()
Determines whether or not the data for this output stream has been retained in memory.void
writeTo(OutputStream out)
Writes the data from this output stream to the specified output stream, after it has been closed.-
Methods inherited from class org.apache.commons.io.output.ThresholdingOutputStream
flush, getByteCount, getThreshold, isThresholdExceeded, write, write, write
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Methods inherited from class java.io.OutputStream
nullOutputStream
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Constructor Detail
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DeferredFileOutputStream
public DeferredFileOutputStream(int threshold, File outputFile)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point. The initial buffer size will default to 1024 bytes which is ByteArrayOutputStream's default buffer size.- Parameters:
threshold
- The number of bytes at which to trigger an event.outputFile
- The file to which data is saved beyond the threshold.
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DeferredFileOutputStream
public DeferredFileOutputStream(int threshold, int initialBufferSize, File outputFile)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a file beyond that point.- Parameters:
threshold
- The number of bytes at which to trigger an event.initialBufferSize
- The initial size of the in memory buffer.outputFile
- The file to which data is saved beyond the threshold.- Since:
- 2.5
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DeferredFileOutputStream
public DeferredFileOutputStream(int threshold, String prefix, String suffix, File directory)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a temporary file beyond that point. The initial buffer size will default to 32 bytes which is ByteArrayOutputStream's default buffer size.- Parameters:
threshold
- The number of bytes at which to trigger an event.prefix
- Prefix to use for the temporary file.suffix
- Suffix to use for the temporary file.directory
- Temporary file directory.- Since:
- 1.4
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DeferredFileOutputStream
public DeferredFileOutputStream(int threshold, int initialBufferSize, String prefix, String suffix, File directory)
Constructs an instance of this class which will trigger an event at the specified threshold, and save data to a temporary file beyond that point.- Parameters:
threshold
- The number of bytes at which to trigger an event.initialBufferSize
- The initial size of the in memory buffer.prefix
- Prefix to use for the temporary file.suffix
- Suffix to use for the temporary file.directory
- Temporary file directory.- Since:
- 2.5
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Method Detail
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isInMemory
public boolean isInMemory()
Determines whether or not the data for this output stream has been retained in memory.- Returns:
true
if the data is available in memory;false
otherwise.
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getData
public byte[] getData()
Returns the data for this output stream as an array of bytes, assuming that the data has been retained in memory. If the data was written to disk, this method returnsnull
.- Returns:
- The data for this output stream, or
null
if no such data is available.
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getFile
public File getFile()
Returns either the output file specified in the constructor or the temporary file created or null.If the constructor specifying the file is used then it returns that same output file, even when threshold has not been reached.
If constructor specifying a temporary file prefix/suffix is used then the temporary file created once the threshold is reached is returned If the threshold was not reached then
null
is returned.- Returns:
- The file for this output stream, or
null
if no such file exists.
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close
public void close() throws IOException
Closes underlying output stream, and mark this as closed- Specified by:
close
in interfaceAutoCloseable
- Specified by:
close
in interfaceCloseable
- Overrides:
close
in classThresholdingOutputStream
- Throws:
IOException
- if an error occurs.
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writeTo
public void writeTo(OutputStream out) throws IOException
Writes the data from this output stream to the specified output stream, after it has been closed.- Parameters:
out
- output stream to write to.- Throws:
IOException
- if this stream is not yet closed or an error occurs.
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