com.google.common.io

## Class FileBackedOutputStream

- java.lang.Object
- - java.io.OutputStream
  - - com.google.common.io.FileBackedOutputStream

- All Implemented Interfaces:
    java.io.Closeable, java.io.Flushable, java.lang.AutoCloseable

      @Beta
      public final class FileBackedOutputStream
      extends java.io.OutputStream

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

  This class is thread-safe.

  Since:
    1.0

- - ### 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

    Methods
    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

    - #### 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 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 java.io.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:
        `java.io.IOException` - if an I/O error occurred while deleting the file buffer

    - #### write

          public void write(int b)
                     throws java.io.IOException

      Specified by:
        `write` in class `java.io.OutputStream`
      Throws:
        `java.io.IOException`

    - #### write

          public void write(byte[] b)
                     throws java.io.IOException

      Overrides:
        `write` in class `java.io.OutputStream`
      Throws:
        `java.io.IOException`

    - #### write

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

      Overrides:
        `write` in class `java.io.OutputStream`
      Throws:
        `java.io.IOException`

    - #### close

          public void close()
                     throws java.io.IOException

      Specified by:
        `close` in interface `java.io.Closeable`
      Specified by:
        `close` in interface `java.lang.AutoCloseable`
      Overrides:
        `close` in class `java.io.OutputStream`
      Throws:
        `java.io.IOException`

    - #### flush

          public void flush()
                     throws java.io.IOException

      Specified by:
        `flush` in interface `java.io.Flushable`
      Overrides:
        `flush` in class `java.io.OutputStream`
      Throws:
        `java.io.IOException`