Package org.apache.commons.io.input
Class MemoryMappedFileInputStream
- java.lang.Object
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- java.io.InputStream
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- org.apache.commons.io.input.MemoryMappedFileInputStream
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public final class MemoryMappedFileInputStream extends java.io.InputStream
AnInputStream
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
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
MemoryMappedFileInputStream.Builder
Builds a newMemoryMappedFileInputStream
instance.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description int
available()
static MemoryMappedFileInputStream.Builder
builder()
Constructs a newMemoryMappedFileInputStream.Builder
.void
close()
int
read()
int
read(byte[] b, int off, int len)
long
skip(long n)
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Method Detail
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builder
public static MemoryMappedFileInputStream.Builder builder()
Constructs a newMemoryMappedFileInputStream.Builder
.- Returns:
- a new
MemoryMappedFileInputStream.Builder
. - Since:
- 2.12.0
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available
public int available() throws java.io.IOException
- Overrides:
available
in classjava.io.InputStream
- Throws:
java.io.IOException
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close
public void close() throws java.io.IOException
- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Overrides:
close
in classjava.io.InputStream
- Throws:
java.io.IOException
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read
public int read() throws java.io.IOException
- Specified by:
read
in classjava.io.InputStream
- Throws:
java.io.IOException
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read
public int read(byte[] b, int off, int len) throws java.io.IOException
- Overrides:
read
in classjava.io.InputStream
- Throws:
java.io.IOException
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skip
public long skip(long n) throws java.io.IOException
- Overrides:
skip
in classjava.io.InputStream
- Throws:
java.io.IOException
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