Class IOUtils
This class provides static utility methods for input/output operations.
- closeQuietly - these methods close a stream ignoring nulls and exceptions
- toXxx/read - these methods read data from a stream
- write - these methods write data to a stream
- copy - these methods copy all the data from one stream to another
- contentEquals - these methods compare the content of two streams
The byte-to-char methods and char-to-byte methods involve a conversion step. Two methods are provided in each case, one that uses the platform default encoding and the other which allows you to specify an encoding. You are encouraged to always specify an encoding because relying on the platform default can lead to unexpected results, for example when moving from development to production.
All the methods in this class that read a stream are buffered internally.
This means that there is no cause to use a BufferedInputStream
or BufferedReader
. The default buffer size of 4K has been shown
to be efficient in tests.
Wherever possible, the methods in this class do not flush or close the stream. This is to avoid making non-portable assumptions about the streams' origin and further use. Thus the caller is still responsible for closing streams after use.
Origin of code: Excalibur.
- Version:
- $Id: IOUtils.java 481854 2006-12-03 18:30:07Z scolebourne $ Code copied from apache commons io source. Changes made (mostly removal of methods) by Per Wendel.
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate static final int
The default buffer size to use.static final String
The system line separator string. -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic int
copy
(InputStream input, OutputStream output) Copies bytes from anInputStream
to anOutputStream
.static void
copy
(InputStream input, Writer output) Copy bytes from anInputStream
to chars on aWriter
using the default character encoding of the platform.static int
Copy chars from aReader
to aWriter
.static long
copyLarge
(InputStream input, OutputStream output) Copies bytes from a large (over 2GB)InputStream
to anOutputStream
.static long
Copy chars from a large (over 2GB)Reader
to aWriter
.static byte[]
toByteArray
(InputStream input) Get the contents of anInputStream
as a ByteArraystatic String
toString
(InputStream input) Get the contents of anInputStream
as a String using the default character encoding of the platform.
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Field Details
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LINE_SEPARATOR
The system line separator string. -
DEFAULT_BUFFER_SIZE
private static final int DEFAULT_BUFFER_SIZEThe default buffer size to use.- See Also:
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Constructor Details
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IOUtils
private IOUtils()
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Method Details
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toString
Get the contents of anInputStream
as a String using the default character encoding of the platform.This method buffers the input internally, so there is no need to use a
BufferedInputStream
.- Parameters:
input
- theInputStream
to read from- Returns:
- the requested String
- Throws:
NullPointerException
- if the input is nullIOException
- if an I/O error occurs
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toByteArray
Get the contents of anInputStream
as a ByteArrayThis method buffers the input internally, so there is no need to use a
BufferedInputStream
.- Parameters:
input
- theInputStream
to read from- Returns:
- the byte array
- Throws:
NullPointerException
- if the input is nullIOException
- if an I/O error occurs
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copy
Copies bytes from anInputStream
to anOutputStream
.This method buffers the input internally, so there is no need to use a
BufferedInputStream
.Large streams (over 2GB) will return a bytes copied value of
-1
after the copy has completed since the correct number of bytes cannot be returned as an int. For large streams use thecopyLarge(InputStream, OutputStream)
method.- Parameters:
input
- theInputStream
to read fromoutput
- theOutputStream
to write to- Returns:
- the number of bytes copied, or -1 if > Integer.MAX_VALUE
- Throws:
NullPointerException
- if the input or output is nullIOException
- if an I/O error occurs- Since:
- Commons IO 1.1
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copyLarge
Copies bytes from a large (over 2GB)InputStream
to anOutputStream
.This method uses the provided buffer, so there is no need to use a
BufferedInputStream
.- Parameters:
input
- theInputStream
to read fromoutput
- theOutputStream
to write to- Returns:
- the number of bytes copied
- Throws:
NullPointerException
- if the input or output is nullIOException
- if an I/O error occurs- Since:
- Commons IO 2.2
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copy
Copy bytes from anInputStream
to chars on aWriter
using the default character encoding of the platform.This method buffers the input internally, so there is no need to use a
BufferedInputStream
.This method uses
InputStreamReader
.- Parameters:
input
- theInputStream
to read fromoutput
- theWriter
to write to- Throws:
NullPointerException
- if the input or output is nullIOException
- if an I/O error occurs- Since:
- Commons IO 1.1
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copy
Copy chars from aReader
to aWriter
.This method buffers the input internally, so there is no need to use a
BufferedReader
.Large streams (over 2GB) will return a chars copied value of
-1
after the copy has completed since the correct number of chars cannot be returned as an int. For large streams use thecopyLarge(Reader, Writer)
method.- Parameters:
input
- theReader
to read fromoutput
- theWriter
to write to- Returns:
- the number of characters copied
- Throws:
NullPointerException
- if the input or output is nullIOException
- if an I/O error occursArithmeticException
- if the character count is too large- Since:
- Commons IO 1.1
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copyLarge
Copy chars from a large (over 2GB)Reader
to aWriter
.This method buffers the input internally, so there is no need to use a
BufferedReader
.- Parameters:
input
- theReader
to read fromoutput
- theWriter
to write to- Returns:
- the number of characters copied
- Throws:
NullPointerException
- if the input or output is nullIOException
- if an I/O error occurs- Since:
- Commons IO 1.3
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