Class BufferAllocator
- java.lang.Object
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- org.simpleframework.common.buffer.FilterAllocator
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- org.simpleframework.common.buffer.BufferAllocator
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public class BufferAllocator extends FilterAllocator implements Buffer
TheBufferAllocator
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
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Field Summary
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Fields inherited from class org.simpleframework.common.buffer.FilterAllocator
capacity, limit, source
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Constructor Summary
Constructors Constructor Description BufferAllocator(Allocator source)
Constructor for theBufferAllocator
object.BufferAllocator(Allocator source, long capacity)
Constructor for theBufferAllocator
object.BufferAllocator(Allocator source, long capacity, long limit)
Constructor for theBufferAllocator
object.
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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.
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Constructor Detail
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BufferAllocator
public BufferAllocator(Allocator source)
Constructor for theBufferAllocator
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
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BufferAllocator
public BufferAllocator(Allocator source, long capacity)
Constructor for theBufferAllocator
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 allocatedcapacity
- the initial capacity of the allocated buffers
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BufferAllocator
public BufferAllocator(Allocator source, long capacity, long limit)
Constructor for theBufferAllocator
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 allocatedcapacity
- the initial capacity of the allocated bufferslimit
- this is the maximum buffer size created by this
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Method Detail
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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.
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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.
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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.
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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.
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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 interfaceBuffer
- Parameters:
array
- this is the byte array to append to this buffersize
- the number of bytes to be read from the arrayoff
- this is the offset to begin reading the bytes from- Returns:
- this returns this buffer for another operation
- Throws:
java.io.IOException
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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.
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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.
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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.
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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 interfaceAllocator
- Overrides:
allocate
in classFilterAllocator
- Parameters:
size
- the initial capacity of the allocated buffer- Returns:
- this returns an allocated buffer with a default size
- Throws:
java.io.IOException
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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.
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