Class NullInputStream
- java.lang.Object
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- java.io.InputStream
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- org.apache.commons.io.input.AbstractInputStream
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- org.apache.commons.io.input.NullInputStream
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- All Implemented Interfaces:
java.io.Closeable
,java.lang.AutoCloseable
public class NullInputStream extends AbstractInputStream
A light weightInputStream
that emulates a stream of a specified size.This implementation provides a light weight object for testing with an
InputStream
where the contents don't matter.One use case would be for testing the handling of large
InputStream
as it can emulate that scenario without the overhead of actually processing large numbers of bytes - significantly speeding up test execution times.This implementation returns zero from the method that reads a byte and leaves the array unchanged in the read methods that are passed a byte array. If alternative data is required the
processByte()
andprocessBytes()
methods can be implemented to generate data, for example:public class TestInputStream extends NullInputStream { public TestInputStream(int size) { super(size); } protected int processByte() { return ... // return required value here } protected void processBytes(byte[] bytes, int offset, int length) { for (int i = offset; i < length; i++) { bytes[i] = ... // set array value here } } }
- Since:
- 1.3
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Field Summary
Fields Modifier and Type Field Description static NullInputStream
INSTANCE
Deprecated.Not reusable without callinginit()
to reset state.
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Constructor Summary
Constructors Constructor Description NullInputStream()
Constructs anInputStream
that emulates a size 0 stream which supports marking and does not throw EOFException.NullInputStream(long size)
Constructs anInputStream
that emulates a specified size which supports marking and does not throw EOFException.NullInputStream(long size, boolean markSupported, boolean throwEofException)
Constructs anInputStream
that emulates a specified size with option settings.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
available()
void
close()
Closes this input stream.long
getPosition()
Gets the current position.long
getSize()
Gets the size thisInputStream
emulates.NullInputStream
init()
Initializes or re-initializes this instance for reuse.void
mark(int readLimit)
Marks the current position.boolean
markSupported()
Tests whether mark is supported.protected int
processByte()
Returns a byte value for theread()
method.protected void
processBytes(byte[] bytes, int offset, int length)
Processes the bytes for theread(byte[], offset, length)
method.int
read()
Reads a byte.int
read(byte[] bytes)
Reads some bytes into the specified array.int
read(byte[] bytes, int offset, int length)
Reads the specified number bytes into an array.void
reset()
Resets the stream to the point when mark was last called.long
skip(long numberOfBytes)
Skips a specified number of bytes.-
Methods inherited from class org.apache.commons.io.input.AbstractInputStream
isClosed, setClosed
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Field Detail
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INSTANCE
@Deprecated public static final NullInputStream INSTANCE
Deprecated.Not reusable without callinginit()
to reset state.The singleton instance.Since instances hold state, call
init()
to reuse.- Since:
- 2.12.0
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Constructor Detail
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NullInputStream
public NullInputStream()
Constructs anInputStream
that emulates a size 0 stream which supports marking and does not throw EOFException.This is an "empty" input stream.
- Since:
- 2.7
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NullInputStream
public NullInputStream(long size)
Constructs anInputStream
that emulates a specified size which supports marking and does not throw EOFException.- Parameters:
size
- The size of the input stream to emulate.
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NullInputStream
public NullInputStream(long size, boolean markSupported, boolean throwEofException)
Constructs anInputStream
that emulates a specified size with option settings.- Parameters:
size
- The size of the input stream to emulate.markSupported
- Whether this instance will support themark()
functionality.throwEofException
- Whether this implementation will throw anEOFException
or return -1 when the end of file is reached.
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Method Detail
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available
public int available()
- Overrides:
available
in classjava.io.InputStream
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close
public void close() throws java.io.IOException
Closes this input stream.- Specified by:
close
in interfacejava.lang.AutoCloseable
- Specified by:
close
in interfacejava.io.Closeable
- Overrides:
close
in classAbstractInputStream
- Throws:
java.io.IOException
- If an error occurs.
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getPosition
public long getPosition()
Gets the current position.- Returns:
- the current position.
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getSize
public long getSize()
Gets the size thisInputStream
emulates.- Returns:
- The size of the input stream to emulate.
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init
public NullInputStream init()
Initializes or re-initializes this instance for reuse.- Returns:
- this instance.
- Since:
- 2.17.0
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mark
public void mark(int readLimit)
Marks the current position.- Overrides:
mark
in classjava.io.InputStream
- Parameters:
readLimit
- The number of bytes before this marked position is invalid.- Throws:
java.lang.UnsupportedOperationException
- if mark is not supported.
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markSupported
public boolean markSupported()
Tests whether mark is supported.- Overrides:
markSupported
in classjava.io.InputStream
- Returns:
- Whether mark is supported or not.
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processByte
protected int processByte()
Returns a byte value for theread()
method.This implementation returns zero.
- Returns:
- This implementation always returns zero.
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processBytes
protected void processBytes(byte[] bytes, int offset, int length)
Processes the bytes for theread(byte[], offset, length)
method.This implementation leaves the byte array unchanged.
- Parameters:
bytes
- The byte arrayoffset
- The offset to start at.length
- The number of bytes.
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read
public int read() throws java.io.IOException
Reads a byte.- Specified by:
read
in classjava.io.InputStream
- Returns:
- Either The byte value returned by
processByte()
or-1
if the end of file has been reached andthrowEofException
is set tofalse
. - Throws:
java.io.EOFException
- if the end of file is reached andthrowEofException
is set totrue
.java.io.IOException
- if trying to read past the end of file.
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read
public int read(byte[] bytes) throws java.io.IOException
Reads some bytes into the specified array.- Overrides:
read
in classjava.io.InputStream
- Parameters:
bytes
- The byte array to read into- Returns:
- The number of bytes read or
-1
if the end of file has been reached andthrowEofException
is set tofalse
. - Throws:
java.io.EOFException
- if the end of file is reached andthrowEofException
is set totrue
.java.io.IOException
- if trying to read past the end of file.
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read
public int read(byte[] bytes, int offset, int length) throws java.io.IOException
Reads the specified number bytes into an array.- Overrides:
read
in classjava.io.InputStream
- Parameters:
bytes
- The byte array to read into.offset
- The offset to start reading bytes into.length
- The number of bytes to read.- Returns:
- The number of bytes read or
-1
if the end of file has been reached andthrowEofException
is set tofalse
. - Throws:
java.io.EOFException
- if the end of file is reached andthrowEofException
is set totrue
.java.io.IOException
- if trying to read past the end of file.
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reset
public void reset() throws java.io.IOException
Resets the stream to the point when mark was last called.- Overrides:
reset
in classjava.io.InputStream
- Throws:
java.lang.UnsupportedOperationException
- if mark is not supported.java.io.IOException
- If no position has been marked or the read limit has been exceeded since the last position was marked.
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skip
public long skip(long numberOfBytes) throws java.io.IOException
Skips a specified number of bytes.- Overrides:
skip
in classjava.io.InputStream
- Parameters:
numberOfBytes
- The number of bytes to skip.- Returns:
- The number of bytes skipped or
-1
if the end of file has been reached andthrowEofException
is set tofalse
. - Throws:
java.io.EOFException
- if the end of file is reached andthrowEofException
is set totrue
.java.io.IOException
- if trying to read past the end of file.
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