Package org.apache.commons.io.output

Class ThresholdingOutputStream

java.lang.Object
java.io.OutputStream
org.apache.commons.io.output.ThresholdingOutputStream
All Implemented Interfaces:
Closeable, Flushable, AutoCloseable
Direct Known Subclasses:
DeferredFileOutputStream
public class ThresholdingOutputStream extends OutputStream
An output stream which triggers an event on the first write that causes the total number of bytes written to the stream to exceed a configured threshold, and every subsequent write. The event can be used, for example, to throw an exception if a maximum has been reached, or to switch the underlying stream when the threshold is exceeded.

This class overrides all OutputStream methods. However, these overrides ultimately call the corresponding methods in the underlying output stream implementation.

NOTE: This implementation may trigger the event before the threshold is actually reached, since it triggers when a pending write operation would cause the threshold to be exceeded.

  • Constructor Summary

    Constructors
    Constructor
    Description
    ThresholdingOutputStream(int threshold)
    Constructs an instance of this class which will trigger an event at the specified threshold.
    ThresholdingOutputStream(int threshold, IOConsumer<ThresholdingOutputStream> thresholdConsumer, IOFunction<ThresholdingOutputStream,OutputStream> outputStreamGetter)
    Constructs an instance of this class which will trigger an event at the specified threshold.

  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    checkThreshold(int count)
    Checks to see if writing the specified number of bytes would cause the configured threshold to be exceeded.
    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.
    long
    getByteCount()
    Gets the number of bytes that have been written to this output stream.
    protected OutputStream
    getOutputStream()
    Gets the underlying output stream, to which the corresponding OutputStream methods in this class will ultimately delegate.
    protected OutputStream
    getStream()
    Deprecated.
    Use getOutputStream().
    int
    getThreshold()
    Gets the threshold, in bytes, at which an event will be triggered.
    boolean
    isThresholdExceeded()
    Tests whether or not the configured threshold has been exceeded for this output stream.
    protected void
    resetByteCount()
    Resets the byteCount to zero.
    protected void
    setByteCount(long count)
    Sets the byteCount to count.
    protected void
    thresholdReached()
    Indicates that the configured threshold has been reached, and that a subclass should take whatever action necessary on this event.
    void
    write(byte[] b)
    Writes b.length bytes from the specified byte array to this output stream.
    void
    write(byte[] b, int off, int len)
    Writes len bytes from the specified byte array starting at offset off to this output stream.
    void
    write(int b)
    Writes the specified byte to this output stream.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • ThresholdingOutputStream

      public ThresholdingOutputStream(int threshold)
      Constructs an instance of this class which will trigger an event at the specified threshold.
      Parameters:
      threshold - The number of bytes at which to trigger an event.

    • ThresholdingOutputStream

      public ThresholdingOutputStream(int threshold, IOConsumer<ThresholdingOutputStream> thresholdConsumer, IOFunction<ThresholdingOutputStream,OutputStream> outputStreamGetter)
      Constructs an instance of this class which will trigger an event at the specified threshold. A negative threshold has no meaning and will be treated as 0
      Parameters:
      threshold - The number of bytes at which to trigger an event.
      thresholdConsumer - Accepts reaching the threshold.
      outputStreamGetter - Gets the output stream.
      Since:
      2.9.0

  • Method Details

    • checkThreshold

      protected void checkThreshold(int count) throws IOException
      Checks to see if writing the specified number of bytes would cause the configured threshold to be exceeded. If so, triggers an event to allow a concrete implementation to take action on this.
      Parameters:
      count - The number of bytes about to be written to the underlying output stream.
      Throws:
      IOException - if an error occurs.

    • close

      public void close() throws IOException
      Closes this output stream and releases any system resources associated with this stream.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class OutputStream
      Throws:
      IOException - if an error occurs.

    • flush

      public void flush() throws IOException
      Flushes this output stream and forces any buffered output bytes to be written out.
      Specified by:
      flush in interface Flushable
      Overrides:
      flush in class OutputStream
      Throws:
      IOException - if an error occurs.

    • getByteCount

      public long getByteCount()
      Gets the number of bytes that have been written to this output stream.
      Returns:
      The number of bytes written.

    • getOutputStream

      protected OutputStream getOutputStream() throws IOException
      Gets the underlying output stream, to which the corresponding OutputStream methods in this class will ultimately delegate.
      Returns:
      The underlying output stream.
      Throws:
      IOException - if an error occurs.
      Since:
      2.14.0

    • getStream

      @Deprecated protected OutputStream getStream() throws IOException
      Deprecated.
      Use getOutputStream().
      Gets the underlying output stream, to which the corresponding OutputStream methods in this class will ultimately delegate.
      Returns:
      The underlying output stream.
      Throws:
      IOException - if an error occurs.

    • getThreshold

      public int getThreshold()
      Gets the threshold, in bytes, at which an event will be triggered.
      Returns:
      The threshold point, in bytes.

    • isThresholdExceeded

      public boolean isThresholdExceeded()
      Tests whether or not the configured threshold has been exceeded for this output stream.
      Returns:
      true if the threshold has been reached; false otherwise.

    • resetByteCount

      protected void resetByteCount()
      Resets the byteCount to zero. You can call this from thresholdReached() if you want the event to be triggered again.

    • setByteCount

      protected void setByteCount(long count)
      Sets the byteCount to count. Useful for re-opening an output stream that has previously been written to.
      Parameters:
      count - The number of bytes that have already been written to the output stream
      Since:
      2.5

    • thresholdReached

      protected void thresholdReached() throws IOException
      Indicates that the configured threshold has been reached, and that a subclass should take whatever action necessary on this event. This may include changing the underlying output stream.
      Throws:
      IOException - if an error occurs.

    • write

      public void write(byte[] b) throws IOException
      Writes b.length bytes from the specified byte array to this output stream.
      Overrides:
      write in class OutputStream
      Parameters:
      b - The array of bytes to be written.
      Throws:
      IOException - if an error occurs.

    • write

      public void write(byte[] b, int off, int len) throws IOException
      Writes len bytes from the specified byte array starting at offset off to this output stream.
      Overrides:
      write in class OutputStream
      Parameters:
      b - The byte array from which the data will be written.
      off - The start offset in the byte array.
      len - The number of bytes to write.
      Throws:
      IOException - if an error occurs.

    • write

      public void write(int b) throws IOException
      Writes the specified byte to this output stream.
      Specified by:
      write in class OutputStream
      Parameters:
      b - The byte to be written.
      Throws:
      IOException - if an error occurs.