org.apache.commons.io.input

Class MemoryMappedFileInputStream

java.lang.Object

java.io.InputStream

org.apache.commons.io.input.MemoryMappedFileInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public final class MemoryMappedFileInputStream
extends java.io.InputStream

An InputStream that utilizes memory mapped files to improve performance. A sliding window of the file is mapped to memory to avoid mapping the entire file to memory at one time. The size of the sliding buffer is configurable.

For most operating systems, mapping a file into memory is more expensive than reading or writing a few tens of kilobytes of data. From the standpoint of performance. it is generally only worth mapping relatively large files into memory.

Note: Use of this class does not necessarily obviate the need to use a BufferedInputStream. Depending on the use case, the use of buffering may still further improve performance. For example:

To build an instance, see MemoryMappedFileInputStream.Builder.

 BufferedInputStream s = new BufferedInputStream(new GzipInputStream(
   MemoryMappedFileInputStream.builder()
     .setPath(path)
     .setBufferSize(256 * 1024)
     .get()));
 

should outperform:

 new GzipInputStream(new MemoryMappedFileInputStream(path))
 

 GzipInputStream s = new GzipInputStream(
   MemoryMappedFileInputStream.builder()
     .setPath(path)
     .setBufferSize(256 * 1024)
     .get());
 

Since:

2.12.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	MemoryMappedFileInputStream.Builder Builds a new MemoryMappedFileInputStream instance.

Method Summary

Modifier and Type	Method and Description
int	available()
static MemoryMappedFileInputStream.Builder	builder() Constructs a new MemoryMappedFileInputStream.Builder.
void	close()
int	read()
int	read(byte[] b, int off, int len)
long	skip(long n)

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset

Methods inherited from class java.lang.Object

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

Method Detail

builder

public static MemoryMappedFileInputStream.Builder builder()

Constructs a new MemoryMappedFileInputStream.Builder.

Returns:

a new MemoryMappedFileInputStream.Builder.

Since:

2.12.0

available

public int available()
              throws java.io.IOException

Overrides:

available in class java.io.InputStream

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

Overrides:

close in class java.io.InputStream

Throws:

java.io.IOException

read

public int read()
         throws java.io.IOException

Specified by:

read in class java.io.InputStream

Throws:

java.io.IOException

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Overrides:

read in class java.io.InputStream

Throws:

java.io.IOException

skip

public long skip(long n)
          throws java.io.IOException

Overrides:

skip in class java.io.InputStream

Throws:

java.io.IOException