Package org.simpleframework.util.buffer

Class FilterAllocator

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable, Allocator
    Direct Known Subclasses:
    BufferAllocator
    public class FilterAllocator
extends java.lang.Object
implements Allocator
    The FilterAllocator object is used to provide a means to provide a general set of constraints around buffer allocation. It can ensure that a minimum capacity is used for default allocation and that an upper limit is used for allocation. In general this can be used in conjunction with another Allocator which may not have such constraints. It ensures that a set of requirements can be observed when allocating buffers.
    Author:
    Niall Gallagher

    • Field Summary

      Fields 
      Modifier and Type Field Description
      protected int capacity
      This is the default initial minimum capacity of the buffer.
      protected int limit
      This is the maximum number of bytes that can be allocated.
      protected Allocator source
      This is the allocator the underlying buffer is allocated with.

    • 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​(int size)
      This method is used to allocate a default buffer.
      void close()
      This method is used to close the allocator so that resources that are occupied by the allocator can be freed.

      • Methods inherited from class java.lang.Object

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

    • Field Detail

      • source

        protected Allocator source
        This is the allocator the underlying buffer is allocated with.

      • capacity

        protected int capacity
        This is the default initial minimum capacity of the buffer.

      • limit

        protected int limit
        This is the maximum number of bytes that can be allocated.

    • Constructor Detail

      • FilterAllocator

        public FilterAllocator​(Allocator source)
        Constructor for the FilterAllocator 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

      • FilterAllocator

        public FilterAllocator​(Allocator source,
                       int capacity)
        Constructor for the FilterAllocator 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

      • FilterAllocator

        public FilterAllocator​(Allocator source,
                       int capacity,
                       int limit)
        Constructor for the FilterAllocator 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

      • 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
        Returns:
        this returns an allocated buffer with a default size
        Throws:
        java.io.IOException

      • allocate

        public Buffer allocate​(int 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
        Parameters:
        size - the initial capacity of the allocated buffer
        Returns:
        this returns an allocated buffer with a default size
        Throws:
        java.io.IOException

      • close

        public void close()
           throws java.io.IOException
        This method is used to close the allocator so that resources that are occupied by the allocator can be freed. This will allow the allocator to be created and closed repeatedly in a single process without holding on to resources such as mapped file buffers or threads.
        Specified by:
        close in interface Allocator
        Specified by:
        close in interface java.lang.AutoCloseable
        Specified by:
        close in interface java.io.Closeable
        Throws:
        java.io.IOException