org.simpleframework.util.buffer
Class FilterAllocator

java.lang.Object
  org.simpleframework.util.buffer.FilterAllocator

All Implemented Interfaces:

Closeable, Allocator

Direct Known Subclasses:

BufferAllocator

public class FilterAllocator
extends 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

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

Constructor Summary

FilterAllocator(Allocator source)
Constructor for the FilterAllocator object.

FilterAllocator(Allocator source, long capacity)
Constructor for the FilterAllocator object.

FilterAllocator(Allocator source, long capacity, long limit)
Constructor for the FilterAllocator object.

Method Summary

Buffer	allocate() This method is used to allocate a default buffer.
Buffer	allocate(long 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 long capacity

This is the default initial minimum capacity of the buffer.

limit

protected long 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,
                       long 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,
                       long capacity,
                       long 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 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:

IOException

allocate

public Buffer allocate(long size)
                throws 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:

IOException

close

public void close()
           throws 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 Closeable

Specified by:

close in interface Allocator

Throws:

IOException