Class BufferAllocator

  • All Implemented Interfaces:
    Allocator, Buffer

    public class BufferAllocator
    extends FilterAllocator
    implements Buffer
    The BufferAllocator object is used to provide a means to allocate buffers using a single underlying buffer. This uses a buffer from a existing allocator to create the region of memory to use to allocate all other buffers. As a result this allows a single buffer to acquire the bytes in a number of associated buffers. This has the advantage of allowing bytes to be read in sequence without joining data from other buffers or allocating multiple regions.
    Author:
    Niall Gallagher
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      Buffer allocate()
      This method is used to allocate a default buffer.
      Buffer allocate​(long size)
      This method is used to allocate a default buffer.
      Buffer append​(byte[] array)
      This method is used to append bytes to the end of the buffer.
      Buffer append​(byte[] array, int off, int size)
      This method is used to append bytes to the end of the buffer.
      void clear()
      This will clear all data from the buffer.
      void close()
      This method is used to ensure the buffer can be closed.
      java.lang.String encode()
      This method is used to acquire the buffered bytes as a string.
      java.lang.String encode​(java.lang.String charset)
      This method is used to acquire the buffered bytes as a string.
      long length()
      This is used to provide the number of bytes that have been written to the buffer.
      java.io.InputStream open()
      This method is used so that a buffer can be represented as a stream of bytes.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • BufferAllocator

        public BufferAllocator​(Allocator source)
        Constructor for the BufferAllocator object. This is used to instantiate the allocator with a default buffer size of half a kilobyte. This ensures that it can be used for general purpose byte storage and for minor I/O tasks.
        Parameters:
        source - this is where the underlying buffer is allocated
      • BufferAllocator

        public BufferAllocator​(Allocator source,
                               long capacity)
        Constructor for the BufferAllocator object. This is used to instantiate the allocator with a specified buffer size. This is typically used when a very specific buffer capacity is required, for example a request body with a known length.
        Parameters:
        source - this is where the underlying buffer is allocated
        capacity - the initial capacity of the allocated buffers
      • BufferAllocator

        public BufferAllocator​(Allocator source,
                               long capacity,
                               long limit)
        Constructor for the BufferAllocator object. This is used to instantiate the allocator with a specified buffer size. This is typically used when a very specific buffer capacity is required, for example a request body with a known length.
        Parameters:
        source - this is where the underlying buffer is allocated
        capacity - the initial capacity of the allocated buffers
        limit - this is the maximum buffer size created by this
    • Method Detail

      • open

        public java.io.InputStream open()
                                 throws java.io.IOException
        This method is used so that a buffer can be represented as a stream of bytes. This provides a quick means to access the data that has been written to the buffer. It wraps the buffer within an input stream so that it can be read directly.
        Specified by:
        open in interface Buffer
        Returns:
        a stream that can be used to read the buffered bytes
        Throws:
        java.io.IOException
      • encode

        public java.lang.String encode()
                                throws java.io.IOException
        This method is used to acquire the buffered bytes as a string. This is useful if the contents need to be manipulated as a string or transferred into another encoding. If the UTF-8 content encoding is not supported the platform default is used, however this is unlikely as UTF-8 should be supported.
        Specified by:
        encode in interface Buffer
        Returns:
        this returns a UTF-8 encoding of the buffer contents
        Throws:
        java.io.IOException
      • encode

        public java.lang.String encode​(java.lang.String charset)
                                throws java.io.IOException
        This method is used to acquire the buffered bytes as a string. This is useful if the contents need to be manipulated as a string or transferred into another encoding. This will convert the bytes using the specified character encoding format.
        Specified by:
        encode in interface Buffer
        Parameters:
        charset - this is the charset to encode the data with
        Returns:
        this returns the encoding of the buffer contents
        Throws:
        java.io.IOException
      • append

        public Buffer append​(byte[] array)
                      throws java.io.IOException
        This method is used to append bytes to the end of the buffer. This will expand the capacity of the buffer if there is not enough space to accommodate the extra bytes.
        Specified by:
        append in interface Buffer
        Parameters:
        array - this is the byte array to append to this buffer
        Returns:
        this returns this buffer for another operation
        Throws:
        java.io.IOException
      • append

        public Buffer append​(byte[] array,
                             int off,
                             int size)
                      throws java.io.IOException
        This method is used to append bytes to the end of the buffer. This will expand the capacity of the buffer if there is not enough space to accommodate the extra bytes.
        Specified by:
        append in interface Buffer
        Parameters:
        array - this is the byte array to append to this buffer
        size - the number of bytes to be read from the array
        off - this is the offset to begin reading the bytes from
        Returns:
        this returns this buffer for another operation
        Throws:
        java.io.IOException
      • clear

        public void clear()
                   throws java.io.IOException
        This will clear all data from the buffer. This simply sets the count to be zero, it will not clear the memory occupied by the instance as the internal buffer will remain. This allows the memory occupied to be reused as many times as is required.
        Specified by:
        clear in interface Buffer
        Throws:
        java.io.IOException
      • close

        public void close()
                   throws java.io.IOException
        This method is used to ensure the buffer can be closed. Once the buffer is closed it is an immutable collection of bytes and can not longer be modified. This ensures that it can be passed by value without the risk of modification of the bytes.
        Specified by:
        close in interface Buffer
        Throws:
        java.io.IOException
      • allocate

        public Buffer allocate()
                        throws java.io.IOException
        This method is used to allocate a default buffer. This will allocate a buffer of predetermined size, allowing it to grow to an upper limit to accommodate extra data. If the buffer requested is larger than the limit an exception is thrown.
        Specified by:
        allocate in interface Allocator
        Specified by:
        allocate in interface Buffer
        Overrides:
        allocate in class FilterAllocator
        Returns:
        this returns an allocated buffer with a default size
        Throws:
        java.io.IOException
      • allocate

        public Buffer allocate​(long size)
                        throws java.io.IOException
        This method is used to allocate a default buffer. This will allocate a buffer of predetermined size, allowing it to grow to an upper limit to accommodate extra data. If the buffer requested is larger than the limit an exception is thrown.
        Specified by:
        allocate in interface Allocator
        Overrides:
        allocate in class FilterAllocator
        Parameters:
        size - the initial capacity of the allocated buffer
        Returns:
        this returns an allocated buffer with a default size
        Throws:
        java.io.IOException
      • length

        public long length()
        This is used to provide the number of bytes that have been written to the buffer. This increases as bytes are appended to the buffer. if the buffer is cleared this resets to zero.
        Specified by:
        length in interface Buffer
        Returns:
        this returns the number of bytes within the buffer