MemFileChannel

java.lang.Object
- java.nio.channels.spi.AbstractInterruptibleChannel
- - java.nio.channels.FileChannel
  - - com.healthmarketscience.jackcess.util.MemFileChannel

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, java.nio.channels.ByteChannel, java.nio.channels.Channel, java.nio.channels.GatheringByteChannel, java.nio.channels.InterruptibleChannel, java.nio.channels.ReadableByteChannel, java.nio.channels.ScatteringByteChannel, java.nio.channels.SeekableByteChannel, java.nio.channels.WritableByteChannel

Direct Known Subclasses:

MemFileChannel.ReadOnlyChannel
```
public class MemFileChannel
extends java.nio.channels.FileChannel
```
FileChannel implementation which maintains the entire "file" in memory. This enables working with a Database entirely in memory (for situations where disk usage may not be possible or desirable). Obviously, this requires enough jvm heap space to fit the file data. Use one of the newChannel() methods to construct an instance of this class.
In order to use this class with a Database, you must use the DatabaseBuilder to open/create the Database instance, passing an instance of this class to the DatabaseBuilder.setChannel(java.nio.channels.FileChannel) method.
Implementation note: this class is optimized for use with Database. Therefore not all methods may be implemented and individual read/write operations are only supported within page boundaries.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

private static class MemFileChannel.ReadOnlyChannel
Subclass of MemFileChannel which is read-only.
- Nested classes/interfaces inherited from class java.nio.channels.FileChannel
  java.nio.channels.FileChannel.MapMode

Nested Classes
Modifier and Type	Class and Description
`private static class`	`MemFileChannel.ReadOnlyChannel` Subclass of MemFileChannel which is read-only.

Field Summary

Fields
Modifier and Type	Field and Description
`private byte[][]`	`_data` chunks containing the file data.
`private long`	`_position` current read/write position
`private long`	`_size` current amount of actual data in the file
`private static int`	`CHUNK_SIZE`
`private static byte[][]`	`EMPTY_DATA`
`private static int`	`INIT_CHUNKS`

Constructor Summary

Constructors
Modifier Constructor and Description

private MemFileChannel()

private MemFileChannel(long position, long size, byte[][] data)

Constructors
Modifier	Constructor and Description
`private`	`MemFileChannel()`
`private`	`MemFileChannel(long position, long size, byte[][] data)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`private void`	`ensureCapacity(long newSize)`
`void`	`force(boolean metaData)`
`private static int`	`getChunkIndex(long pos)`
`private static int`	`getChunkOffset(long pos)`
`private static int`	`getNumChunks(long size)`
`protected void`	`implCloseChannel()`
`java.nio.channels.FileLock`	`lock(long position, long size, boolean shared)`
`java.nio.MappedByteBuffer`	`map(java.nio.channels.FileChannel.MapMode mode, long position, long size)`
`static MemFileChannel`	`newChannel()` Creates a new read/write, empty MemFileChannel.
`static MemFileChannel`	`newChannel(java.io.File file)` Creates a new read/write MemFileChannel containing the contents of the given File.
`static MemFileChannel`	`newChannel(java.io.File file, java.lang.String mode)` Creates a new MemFileChannel containing the contents of the given File with the given mode (for mode details see `RandomAccessFile(File,String)`).
`static MemFileChannel`	`newChannel(java.io.InputStream in)` Creates a new read/write MemFileChannel containing the contents of the given InputStream.
`static MemFileChannel`	`newChannel(java.io.InputStream in, java.lang.String mode)` Creates a new MemFileChannel containing the contents of the given InputStream with the given mode (for mode details see `RandomAccessFile(File,String)`).
`static MemFileChannel`	`newChannel(java.nio.channels.ReadableByteChannel in)` Creates a new read/write MemFileChannel containing the contents of the given ReadableByteChannel.
`static MemFileChannel`	`newChannel(java.nio.channels.ReadableByteChannel in, java.lang.String mode)` Creates a new MemFileChannel containing the contents of the given ReadableByteChannel with the given mode (for mode details see `RandomAccessFile(File,String)`).
`long`	`position()`
`java.nio.channels.FileChannel`	`position(long newPosition)`
`int`	`read(java.nio.ByteBuffer dst)`
`long`	`read(java.nio.ByteBuffer[] dsts, int offset, int length)`
`int`	`read(java.nio.ByteBuffer dst, long position)`
`long`	`size()`
`long`	`transferFrom(java.nio.channels.ReadableByteChannel src, long position, long count)`
`long`	`transferTo(long position, long count, java.io.OutputStream dst)` Convenience method for writing the selected portion of this channel to the given destination stream.
`long`	`transferTo(long position, long count, java.nio.channels.WritableByteChannel dst)`
`long`	`transferTo(java.io.OutputStream dst)` Convenience method for writing the entire contents of this channel to the given destination stream.
`long`	`transferTo(java.nio.channels.WritableByteChannel dst)` Convenience method for writing the entire contents of this channel to the given destination channel.
`java.nio.channels.FileChannel`	`truncate(long newSize)`
`java.nio.channels.FileLock`	`tryLock(long position, long size, boolean shared)`
`int`	`write(java.nio.ByteBuffer src)`
`long`	`write(java.nio.ByteBuffer[] srcs, int offset, int length)`
`int`	`write(java.nio.ByteBuffer src, long position)`

Methods inherited from class java.nio.channels.FileChannel
lock, open, open, read, tryLock, write

Methods inherited from class java.nio.channels.spi.AbstractInterruptibleChannel
begin, close, end, isOpen

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.nio.channels.Channel
close, isOpen

- Field Detail
  - EMPTY_DATA
```
private static final byte[][] EMPTY_DATA
```
  - CHUNK_SIZE
```
private static final int CHUNK_SIZE
```
    See Also:
    
    Constant Field Values
  - INIT_CHUNKS
```
private static final int INIT_CHUNKS
```
    See Also:
    
    Constant Field Values
  - _position
```
private long _position
```
    current read/write position
  - _size
```
private long _size
```
    current amount of actual data in the file
  - _data
```
private byte[][] _data
```
    chunks containing the file data. the length of the chunk array is always a power of 2 and the chunks are always CHUNK_SIZE.
- Constructor Detail
  - MemFileChannel
```
private MemFileChannel()
```
  - MemFileChannel
```
private MemFileChannel(long position,
                       long size,
                       byte[][] data)
```
- Method Detail
  - newChannel
```
public static MemFileChannel newChannel()
```
    Creates a new read/write, empty MemFileChannel.
  - newChannel
```
public static MemFileChannel newChannel(java.io.File file)
                                 throws java.io.IOException
```
    Creates a new read/write MemFileChannel containing the contents of the given File. Note, modifications to the returned channel will not affect the original File source.
    
    Throws:
    
    java.io.IOException
  - newChannel
```
public static MemFileChannel newChannel(java.io.File file,
                                        java.lang.String mode)
                                 throws java.io.IOException
```
    Creates a new MemFileChannel containing the contents of the given File with the given mode (for mode details see RandomAccessFile(File,String)). Note, modifications to the returned channel will not affect the original File source.
    
    Throws:
    
    java.io.IOException
  - newChannel
```
public static MemFileChannel newChannel(java.io.InputStream in)
                                 throws java.io.IOException
```
    Creates a new read/write MemFileChannel containing the contents of the given InputStream.
    
    Throws:
    
    java.io.IOException
  - newChannel
```
public static MemFileChannel newChannel(java.io.InputStream in,
                                        java.lang.String mode)
                                 throws java.io.IOException
```
    Creates a new MemFileChannel containing the contents of the given InputStream with the given mode (for mode details see RandomAccessFile(File,String)).
    
    Throws:
    
    java.io.IOException
  - newChannel
```
public static MemFileChannel newChannel(java.nio.channels.ReadableByteChannel in)
                                 throws java.io.IOException
```
    Creates a new read/write MemFileChannel containing the contents of the given ReadableByteChannel.
    
    Throws:
    
    java.io.IOException
  - newChannel
```
public static MemFileChannel newChannel(java.nio.channels.ReadableByteChannel in,
                                        java.lang.String mode)
                                 throws java.io.IOException
```
    Creates a new MemFileChannel containing the contents of the given ReadableByteChannel with the given mode (for mode details see RandomAccessFile(File,String)).
    
    Throws:
    
    java.io.IOException
  - read
```
public int read(java.nio.ByteBuffer dst)
         throws java.io.IOException
```
    Specified by:
    
    read in interface java.nio.channels.ReadableByteChannel
    
    Specified by:
    
    read in interface java.nio.channels.SeekableByteChannel
    
    Specified by:
    
    read in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - read
```
public int read(java.nio.ByteBuffer dst,
                long position)
         throws java.io.IOException
```
    Specified by:
    
    read in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - write
```
public int write(java.nio.ByteBuffer src)
          throws java.io.IOException
```
    Specified by:
    
    write in interface java.nio.channels.SeekableByteChannel
    
    Specified by:
    
    write in interface java.nio.channels.WritableByteChannel
    
    Specified by:
    
    write in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - write
```
public int write(java.nio.ByteBuffer src,
                 long position)
          throws java.io.IOException
```
    Specified by:
    
    write in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - position
```
public long position()
              throws java.io.IOException
```
    Specified by:
    
    position in interface java.nio.channels.SeekableByteChannel
    
    Specified by:
    
    position in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - position
```
public java.nio.channels.FileChannel position(long newPosition)
                                       throws java.io.IOException
```
    Specified by:
    
    position in interface java.nio.channels.SeekableByteChannel
    
    Overrides:
    
    position in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - size
```
public long size()
          throws java.io.IOException
```
    Specified by:
    
    size in interface java.nio.channels.SeekableByteChannel
    
    Specified by:
    
    size in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - truncate
```
public java.nio.channels.FileChannel truncate(long newSize)
                                       throws java.io.IOException
```
    Specified by:
    
    truncate in interface java.nio.channels.SeekableByteChannel
    
    Overrides:
    
    truncate in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - force
```
public void force(boolean metaData)
           throws java.io.IOException
```
    Specified by:
    
    force in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - transferTo
```
public long transferTo(java.nio.channels.WritableByteChannel dst)
                throws java.io.IOException
```
    Convenience method for writing the entire contents of this channel to the given destination channel.
    
    Throws:
    
    java.io.IOException
    
    See Also:
    
    transferTo(long,long,WritableByteChannel)
  - transferTo
```
public long transferTo(long position,
                       long count,
                       java.nio.channels.WritableByteChannel dst)
                throws java.io.IOException
```
    Specified by:
    
    transferTo in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - transferTo
```
public long transferTo(java.io.OutputStream dst)
                throws java.io.IOException
```
    Convenience method for writing the entire contents of this channel to the given destination stream.
    
    Throws:
    
    java.io.IOException
    
    See Also:
    
    transferTo(long,long,WritableByteChannel)
  - transferTo
```
public long transferTo(long position,
                       long count,
                       java.io.OutputStream dst)
                throws java.io.IOException
```
    Convenience method for writing the selected portion of this channel to the given destination stream.
    
    Throws:
    
    java.io.IOException
    
    See Also:
    
    transferTo(long,long,WritableByteChannel)
  - transferFrom
```
public long transferFrom(java.nio.channels.ReadableByteChannel src,
                         long position,
                         long count)
                  throws java.io.IOException
```
    Specified by:
    
    transferFrom in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - implCloseChannel
```
protected void implCloseChannel()
                         throws java.io.IOException
```
    Specified by:
    
    implCloseChannel in class java.nio.channels.spi.AbstractInterruptibleChannel
    
    Throws:
    
    java.io.IOException
  - ensureCapacity
```
private void ensureCapacity(long newSize)
```
  - getChunkIndex
```
private static int getChunkIndex(long pos)
```
  - getChunkOffset
```
private static int getChunkOffset(long pos)
```
  - getNumChunks
```
private static int getNumChunks(long size)
```
  - write
```
public long write(java.nio.ByteBuffer[] srcs,
                  int offset,
                  int length)
           throws java.io.IOException
```
    Specified by:
    
    write in interface java.nio.channels.GatheringByteChannel
    
    Specified by:
    
    write in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - read
```
public long read(java.nio.ByteBuffer[] dsts,
                 int offset,
                 int length)
          throws java.io.IOException
```
    Specified by:
    
    read in interface java.nio.channels.ScatteringByteChannel
    
    Specified by:
    
    read in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - map
```
public java.nio.MappedByteBuffer map(java.nio.channels.FileChannel.MapMode mode,
                                     long position,
                                     long size)
                              throws java.io.IOException
```
    Specified by:
    
    map in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - lock
```
public java.nio.channels.FileLock lock(long position,
                                       long size,
                                       boolean shared)
                                throws java.io.IOException
```
    Specified by:
    
    lock in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException
  - tryLock
```
public java.nio.channels.FileLock tryLock(long position,
                                          long size,
                                          boolean shared)
                                   throws java.io.IOException
```
    Specified by:
    
    tryLock in class java.nio.channels.FileChannel
    
    Throws:
    
    java.io.IOException

Class MemFileChannel

Nested Class Summary

Nested classes/interfaces inherited from class java.nio.channels.FileChannel

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.nio.channels.FileChannel

Methods inherited from class java.nio.channels.spi.AbstractInterruptibleChannel

Methods inherited from class java.lang.Object

Methods inherited from interface java.nio.channels.Channel

Field Detail

EMPTY_DATA

CHUNK_SIZE

INIT_CHUNKS

_position

_size

_data

Constructor Detail

MemFileChannel

MemFileChannel

Method Detail

newChannel

newChannel

newChannel

newChannel

newChannel

newChannel

newChannel

read

read

write

write

position

position

size

truncate

force

transferTo

transferTo

transferTo

transferTo

transferFrom

implCloseChannel

ensureCapacity

getChunkIndex

getChunkOffset

getNumChunks

write

read

map

lock

tryLock