Package org.apache.commons.io.input.buffer

Class CircularByteBuffer

  • public class CircularByteBuffer
extends java.lang.Object
    A buffer, which doesn't need reallocation of byte arrays, because it reuses a single byte array. This works particularly well, if reading from the buffer takes place at the same time than writing to. Such is the case, for example, when using the buffer within a filtering input stream, like the CircularBufferInputStream.

    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void add​(byte value)
      Adds a new byte to the buffer, which will eventually be returned by following invocations of read().
      void add​(byte[] targetBuffer, int offset, int length)
      Adds the given bytes to the buffer.
      void clear()
      Removes all bytes from the buffer.
      int getCurrentNumberOfBytes()
      Returns the number of bytes, that are currently present in the buffer.
      int getSpace()
      Returns the number of bytes, that can currently be added to the buffer.
      boolean hasBytes()
      Returns, whether the buffer is currently holding, at least, a single byte.
      boolean hasSpace()
      Returns, whether there is currently room for a single byte in the buffer.
      boolean hasSpace​(int count)
      Returns, whether there is currently room for the given number of bytes in the buffer.
      boolean peek​(byte[] sourceBuffer, int offset, int length)
      Returns, whether the next bytes in the buffer are exactly those, given by sourceBuffer, offset, and length.
      byte read()
      Returns the next byte from the buffer, removing it at the same time, so that following invocations won't return it again.
      void read​(byte[] targetBuffer, int targetOffset, int length)
      Returns the given number of bytes from the buffer by storing them in the given byte array at the given offset.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • CircularByteBuffer

        public CircularByteBuffer​(int size)
        Creates a new instance with the given buffer size.
        Parameters:
        size - the size of buffer to create

      • CircularByteBuffer

        public CircularByteBuffer()
        Creates a new instance with a reasonable default buffer size (IOUtils.DEFAULT_BUFFER_SIZE).

    • Method Detail

      • read

        public byte read()
        Returns the next byte from the buffer, removing it at the same time, so that following invocations won't return it again.
        Returns:
        The byte, which is being returned.
        Throws:
        java.lang.IllegalStateException - The buffer is empty. Use hasBytes(), or getCurrentNumberOfBytes(), to prevent this exception.

      • read

        public void read​(byte[] targetBuffer,
                 int targetOffset,
                 int length)
        Returns the given number of bytes from the buffer by storing them in the given byte array at the given offset.
        Parameters:
        targetBuffer - The byte array, where to add bytes.
        targetOffset - The offset, where to store bytes in the byte array.
        length - The number of bytes to return.
        Throws:
        java.lang.NullPointerException - The byte array pBuffer is null.
        java.lang.IllegalArgumentException - Either of pOffset, or length is negative, or the length of the byte array targetBuffer is too small.
        java.lang.IllegalStateException - The buffer doesn't hold the given number of bytes. Use getCurrentNumberOfBytes() to prevent this exception.

      • add

        public void add​(byte value)
        Adds a new byte to the buffer, which will eventually be returned by following invocations of read().
        Parameters:
        value - The byte, which is being added to the buffer.
        Throws:
        java.lang.IllegalStateException - The buffer is full. Use hasSpace(), or getSpace(), to prevent this exception.

      • peek

        public boolean peek​(byte[] sourceBuffer,
                    int offset,
                    int length)
        Returns, whether the next bytes in the buffer are exactly those, given by sourceBuffer, offset, and length. No bytes are being removed from the buffer. If the result is true, then the following invocations of read() are guaranteed to return exactly those bytes.
        Parameters:
        sourceBuffer - the buffer to compare against
        offset - start offset
        length - length to compare
        Returns:
        True, if the next invocations of read() will return the bytes at offsets pOffset+0, pOffset+1, ..., pOffset+length-1 of byte array pBuffer.
        Throws:
        java.lang.IllegalArgumentException - Either of pOffset, or length is negative.
        java.lang.NullPointerException - The byte array pBuffer is null.

      • add

        public void add​(byte[] targetBuffer,
                int offset,
                int length)
        Adds the given bytes to the buffer. This is the same as invoking add(byte) for the bytes at offsets offset+0, offset+1, ..., offset+length-1 of byte array targetBuffer.
        Parameters:
        targetBuffer - the buffer to copy
        offset - start offset
        length - length to copy
        Throws:
        java.lang.IllegalStateException - The buffer doesn't have sufficient space. Use getSpace() to prevent this exception.
        java.lang.IllegalArgumentException - Either of offset, or length is negative.
        java.lang.NullPointerException - The byte array pBuffer is null.

      • hasSpace

        public boolean hasSpace()
        Returns, whether there is currently room for a single byte in the buffer. Same as hasSpace(1).
        Returns:
        true if there is space for a byte
        See Also:
        hasSpace(int), getSpace()

      • hasSpace

        public boolean hasSpace​(int count)
        Returns, whether there is currently room for the given number of bytes in the buffer.
        Parameters:
        count - the byte count
        Returns:
        true if there is space for the given number of bytes
        See Also:
        hasSpace(), getSpace()

      • hasBytes

        public boolean hasBytes()
        Returns, whether the buffer is currently holding, at least, a single byte.
        Returns:
        true if the buffer is not empty

      • getSpace

        public int getSpace()
        Returns the number of bytes, that can currently be added to the buffer.
        Returns:
        the number of bytes that can be added

      • getCurrentNumberOfBytes

        public int getCurrentNumberOfBytes()
        Returns the number of bytes, that are currently present in the buffer.
        Returns:
        the number of bytes

      • clear

        public void clear()
        Removes all bytes from the buffer.