FileRegion

All Superinterfaces:

ExternalResourceReleasable

All Known Implementing Classes:

DefaultFileRegion
```
public interface FileRegion
extends ExternalResourceReleasable
```
A region of a file that is sent via a Channel which supports zero-copy file transfer.
Upgrade your JDK / JRE
FileChannel.transferTo(long, long, WritableByteChannel) has at least four known bugs in the old versions of Sun JDK and perhaps its derived ones. Please upgrade your JDK to 1.6.0_18 or later version if you are going to use zero-copy file transfer.
- 5103988 - FileChannel.transferTo() should return -1 for EAGAIN instead throws IOException
- 6253145 - FileChannel.transferTo() on Linux fails when going beyond 2GB boundary
- 6427312 - FileChannel.transferTo() throws IOException "system call interrupted"
- 6470086 - FileChannel.transferTo(2147483647, 1, channel) causes "Value too large" exception
Check your operating system and JDK / JRE
If your operating system (or JDK / JRE) does not support zero-copy file transfer, sending a file with FileRegion might fail or yield worse performance. For example, sending a large file doesn't work well in Windows.
Not all transports support it
Currently, the NIO transport is the only transport that supports FileRegion. Attempting to write a FileRegion to non-NIO Channel will trigger a ClassCastException or a similar exception.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`long`	`getCount()`	Returns the number of bytes to transfer.
`long`	`getPosition()`	Returns the offset in the file where the transfer began.
`long`	`transferTo(java.nio.channels.WritableByteChannel target, long position)`	Transfers the content of this file region to the specified channel.

Methods inherited from interface org.jboss.netty.util.ExternalResourceReleasable
releaseExternalResources

- Method Detail
  - getPosition
```
long getPosition()
```
    Returns the offset in the file where the transfer began.
  - getCount
```
long getCount()
```
    Returns the number of bytes to transfer.
  - transferTo
```
long transferTo(java.nio.channels.WritableByteChannel target,
                long position)
         throws java.io.IOException
```
    Transfers the content of this file region to the specified channel.
    
    Parameters:
    
    target - the destination of the transfer
    
    position - the relative offset of the file where the transfer begins from. For example, 0 will make the transfer start from getPosition()th byte and getCount() - 1 will make the last byte of the region transferred.
    
    Throws:
    
    java.io.IOException