org.apache.commons.io
public class IOUtils extends Object
This class provides static utility methods for input/output operations.
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 $
Field Summary | |
---|---|
static int | DEFAULT_BUFFER_SIZE
The default buffer size to use. |
static char | DIR_SEPARATOR
The system directory separator character. |
static char | DIR_SEPARATOR_UNIX
The Unix directory separator character. |
static char | DIR_SEPARATOR_WINDOWS
The Windows directory separator character. |
static String | LINE_SEPARATOR
The system line separator string. |
static String | LINE_SEPARATOR_UNIX
The Unix line separator string. |
static String | LINE_SEPARATOR_WINDOWS
The Windows line separator string. |
Constructor Summary | |
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IOUtils()
Instances should NOT be constructed in standard programming. |
Method Summary | |
---|---|
static void | closeQuietly(Reader input)
Unconditionally close an Reader .
|
static void | closeQuietly(Writer output)
Unconditionally close a Writer .
|
static void | closeQuietly(InputStream input)
Unconditionally close an InputStream .
|
static void | closeQuietly(OutputStream output)
Unconditionally close an OutputStream .
|
static boolean | contentEquals(InputStream input1, InputStream input2)
Compare the contents of two Streams to determine if they are equal or
not.
|
static boolean | contentEquals(Reader input1, Reader input2)
Compare the contents of two Readers to determine if they are equal or
not.
|
static int | copy(InputStream input, OutputStream output)
Copy bytes from an InputStream to an
OutputStream .
|
static void | copy(InputStream input, Writer output)
Copy bytes from an InputStream to chars on a
Writer using the default character encoding of the platform.
|
static void | copy(InputStream input, Writer output, String encoding)
Copy bytes from an InputStream to chars on a
Writer using the specified character encoding.
|
static int | copy(Reader input, Writer output)
Copy chars from a Reader to a Writer .
|
static void | copy(Reader input, OutputStream output)
Copy chars from a Reader to bytes on an
OutputStream using the default character encoding of the
platform, and calling flush.
|
static void | copy(Reader input, OutputStream output, String encoding)
Copy chars from a Reader to bytes on an
OutputStream using the specified character encoding, and
calling flush.
|
static long | copyLarge(InputStream input, OutputStream output)
Copy bytes from a large (over 2GB) InputStream to an
OutputStream .
|
static long | copyLarge(Reader input, Writer output)
Copy chars from a large (over 2GB) Reader to a Writer .
|
static LineIterator | lineIterator(Reader reader)
Return an Iterator for the lines in a Reader .
|
static LineIterator | lineIterator(InputStream input, String encoding)
Return an Iterator for the lines in an InputStream , using
the character encoding specified (or default encoding if null).
|
static List | readLines(InputStream input)
Get the contents of an InputStream as a list of Strings,
one entry per line, using the default character encoding of the platform.
|
static List | readLines(InputStream input, String encoding)
Get the contents of an InputStream as a list of Strings,
one entry per line, using the specified character encoding.
|
static List | readLines(Reader input)
Get the contents of a Reader as a list of Strings,
one entry per line.
|
static byte[] | toByteArray(InputStream input)
Get the contents of an InputStream as a byte[] .
|
static byte[] | toByteArray(Reader input)
Get the contents of a Reader as a byte[]
using the default character encoding of the platform.
|
static byte[] | toByteArray(Reader input, String encoding)
Get the contents of a Reader as a byte[]
using the specified character encoding.
|
static byte[] | toByteArray(String input)
Get the contents of a String as a byte[]
using the default character encoding of the platform.
|
static char[] | toCharArray(InputStream is)
Get the contents of an InputStream as a character array
using the default character encoding of the platform.
|
static char[] | toCharArray(InputStream is, String encoding)
Get the contents of an InputStream as a character array
using the specified character encoding.
|
static char[] | toCharArray(Reader input)
Get the contents of a Reader as a character array.
|
static InputStream | toInputStream(String input)
Convert the specified string to an input stream, encoded as bytes
using the default character encoding of the platform.
|
static InputStream | toInputStream(String input, String encoding)
Convert the specified string to an input stream, encoded as bytes
using the specified character encoding.
|
static String | toString(InputStream input)
Get the contents of an InputStream as a String
using the default character encoding of the platform.
|
static String | toString(InputStream input, String encoding)
Get the contents of an InputStream as a String
using the specified character encoding.
|
static String | toString(Reader input)
Get the contents of a Reader as a String.
|
static String | toString(byte[] input)
Get the contents of a byte[] as a String
using the default character encoding of the platform.
|
static String | toString(byte[] input, String encoding)
Get the contents of a byte[] as a String
using the specified character encoding.
|
static void | write(byte[] data, OutputStream output)
Writes bytes from a byte[] to an OutputStream .
|
static void | write(byte[] data, Writer output)
Writes bytes from a byte[] to chars on a Writer
using the default character encoding of the platform.
|
static void | write(byte[] data, Writer output, String encoding)
Writes bytes from a byte[] to chars on a Writer
using the specified character encoding.
|
static void | write(char[] data, Writer output)
Writes chars from a char[] to a Writer
using the default character encoding of the platform.
|
static void | write(char[] data, OutputStream output)
Writes chars from a char[] to bytes on an
OutputStream .
|
static void | write(char[] data, OutputStream output, String encoding)
Writes chars from a char[] to bytes on an
OutputStream using the specified character encoding.
|
static void | write(String data, Writer output)
Writes chars from a String to a Writer .
|
static void | write(String data, OutputStream output)
Writes chars from a String to bytes on an
OutputStream using the default character encoding of the
platform.
|
static void | write(String data, OutputStream output, String encoding)
Writes chars from a String to bytes on an
OutputStream using the specified character encoding.
|
static void | write(StringBuffer data, Writer output)
Writes chars from a StringBuffer to a Writer .
|
static void | write(StringBuffer data, OutputStream output)
Writes chars from a StringBuffer to bytes on an
OutputStream using the default character encoding of the
platform.
|
static void | write(StringBuffer data, OutputStream output, String encoding)
Writes chars from a StringBuffer to bytes on an
OutputStream using the specified character encoding.
|
static void | writeLines(Collection lines, String lineEnding, OutputStream output)
Writes the toString() value of each item in a collection to
an OutputStream line by line, using the default character
encoding of the platform and the specified line ending.
|
static void | writeLines(Collection lines, String lineEnding, OutputStream output, String encoding)
Writes the toString() value of each item in a collection to
an OutputStream line by line, using the specified character
encoding and the specified line ending.
|
static void | writeLines(Collection lines, String lineEnding, Writer writer)
Writes the toString() value of each item in a collection to
a Writer line by line, using the specified line ending.
|
Reader
.
Equivalent to Reader#close(), except any exceptions will be ignored. This is typically used in finally blocks.
Parameters: input the Reader to close, may be null or already closed
Writer
.
Equivalent to Writer#close(), except any exceptions will be ignored. This is typically used in finally blocks.
Parameters: output the Writer to close, may be null or already closed
InputStream
.
Equivalent to InputStream#close(), except any exceptions will be ignored. This is typically used in finally blocks.
Parameters: input the InputStream to close, may be null or already closed
OutputStream
.
Equivalent to OutputStream#close(), except any exceptions will be ignored. This is typically used in finally blocks.
Parameters: output the OutputStream to close, may be null or already closed
This method buffers the input internally using
BufferedInputStream
if they are not already buffered.
Parameters: input1 the first stream input2 the second stream
Returns: true if the content of the streams are equal or they both don't exist, false otherwise
Throws: NullPointerException if either input is null IOException if an I/O error occurs
This method buffers the input internally using
BufferedReader
if they are not already buffered.
Parameters: input1 the first reader input2 the second reader
Returns: true if the content of the readers are equal or they both don't exist, false otherwise
Throws: NullPointerException if either input is null IOException if an I/O error occurs
Since: Commons IO 1.1
InputStream
to an
OutputStream
.
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 the copyLarge(InputStream, OutputStream)
method.
Parameters: input the InputStream
to read from output the OutputStream
to write to
Returns: the number of bytes copied
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs ArithmeticException if the byte count is too large
Since: Commons IO 1.1
InputStream
to chars on a
Writer
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 the InputStream
to read from output the Writer
to write to
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs
Since: Commons IO 1.1
InputStream
to chars on a
Writer
using the specified character encoding.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
Character encoding names can be found at IANA.
This method uses InputStreamReader.
Parameters: input the InputStream
to read from output the Writer
to write to encoding the encoding to use, null means platform default
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs
Since: Commons IO 1.1
Reader
to a Writer
.
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 the copyLarge(Reader, Writer)
method.
Parameters: input the Reader
to read from output the Writer
to write to
Returns: the number of characters copied
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs ArithmeticException if the character count is too large
Since: Commons IO 1.1
Reader
to bytes on an
OutputStream
using the default character encoding of the
platform, and calling flush.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Due to the implementation of OutputStreamWriter, this method performs a flush.
This method uses OutputStreamWriter.
Parameters: input the Reader
to read from output the OutputStream
to write to
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs
Since: Commons IO 1.1
Reader
to bytes on an
OutputStream
using the specified character encoding, and
calling flush.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Character encoding names can be found at IANA.
Due to the implementation of OutputStreamWriter, this method performs a flush.
This method uses OutputStreamWriter.
Parameters: input the Reader
to read from output the OutputStream
to write to encoding the encoding to use, null means platform default
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs
Since: Commons IO 1.1
InputStream
to an
OutputStream
.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
Parameters: input the InputStream
to read from output the OutputStream
to write to
Returns: the number of bytes copied
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs
Since: Commons IO 1.3
Reader
to a Writer
.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Parameters: input the Reader
to read from output the Writer
to write to
Returns: the number of characters copied
Throws: NullPointerException if the input or output is null IOException if an I/O error occurs
Since: Commons IO 1.3
Reader
.
LineIterator
holds a reference to the open
Reader
specified here. When you have finished with the
iterator you should close the reader to free internal resources.
This can be done by closing the reader directly, or by calling
close or closeQuietly.
The recommended usage pattern is:
try { LineIterator it = IOUtils.lineIterator(reader); while (it.hasNext()) { String line = it.nextLine(); /// do something with line } } finally { IOUtils.closeQuietly(reader); }
Parameters: reader the Reader
to read from, not null
Returns: an Iterator of the lines in the reader, never null
Throws: IllegalArgumentException if the reader is null
Since: Commons IO 1.2
InputStream
, using
the character encoding specified (or default encoding if null).
LineIterator
holds a reference to the open
InputStream
specified here. When you have finished with
the iterator you should close the stream to free internal resources.
This can be done by closing the stream directly, or by calling
close or closeQuietly.
The recommended usage pattern is:
try { LineIterator it = IOUtils.lineIterator(stream, "UTF-8"); while (it.hasNext()) { String line = it.nextLine(); /// do something with line } } finally { IOUtils.closeQuietly(stream); }
Parameters: input the InputStream
to read from, not null encoding the encoding to use, null means platform default
Returns: an Iterator of the lines in the reader, never null
Throws: IllegalArgumentException if the input is null IOException if an I/O error occurs, such as if the encoding is invalid
Since: Commons IO 1.2
InputStream
as a list of Strings,
one entry per line, 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 the InputStream
to read from, not null
Returns: the list of Strings, never null
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1
InputStream
as a list of Strings,
one entry per line, using the specified character encoding.
Character encoding names can be found at IANA.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
Parameters: input the InputStream
to read from, not null encoding the encoding to use, null means platform default
Returns: the list of Strings, never null
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1
Reader
as a list of Strings,
one entry per line.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Parameters: input the Reader
to read from, not null
Returns: the list of Strings, never null
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1
InputStream
as a byte[]
.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
Parameters: input the InputStream
to read from
Returns: the requested byte array
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Reader
as a byte[]
using the default character encoding of the platform.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Parameters: input the Reader
to read from
Returns: the requested byte array
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Reader
as a byte[]
using the specified character encoding.
Character encoding names can be found at IANA.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Parameters: input the Reader
to read from encoding the encoding to use, null means platform default
Returns: the requested byte array
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1
Deprecated: Use String#getBytes()
Get the contents of aString
as a byte[]
using the default character encoding of the platform.
This is the same as String#getBytes().
Parameters: input the String
to convert
Returns: the requested byte array
Throws: NullPointerException if the input is null IOException if an I/O error occurs (never occurs)
InputStream
as a character array
using the default character encoding of the platform.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
Parameters: is the InputStream
to read from
Returns: the requested character array
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1
InputStream
as a character array
using the specified character encoding.
Character encoding names can be found at IANA.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
Parameters: is the InputStream
to read from encoding the encoding to use, null means platform default
Returns: the requested character array
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1
Reader
as a character array.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Parameters: input the Reader
to read from
Returns: the requested character array
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1
Parameters: input the string to convert
Returns: an input stream
Since: Commons IO 1.1
Character encoding names can be found at IANA.
Parameters: input the string to convert encoding the encoding to use, null means platform default
Returns: an input stream
Throws: IOException if the encoding is invalid
Since: Commons IO 1.1
InputStream
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 the InputStream
to read from
Returns: the requested String
Throws: NullPointerException if the input is null IOException if an I/O error occurs
InputStream
as a String
using the specified character encoding.
Character encoding names can be found at IANA.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
Parameters: input the InputStream
to read from encoding the encoding to use, null means platform default
Returns: the requested String
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Reader
as a String.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
Parameters: input the Reader
to read from
Returns: the requested String
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Deprecated: Use String#String(byte[])
byte[]
as a String
using the default character encoding of the platform.
Parameters: input the byte array to read from
Returns: the requested String
Throws: NullPointerException if the input is null IOException if an I/O error occurs (never occurs)
Deprecated: Use String#String(byte[],String)
byte[]
as a String
using the specified character encoding.
Character encoding names can be found at IANA.
Parameters: input the byte array to read from encoding the encoding to use, null means platform default
Returns: the requested String
Throws: NullPointerException if the input is null IOException if an I/O error occurs (never occurs)
byte[]
to an OutputStream
.
Parameters: data the byte array to write, do not modify during output,
null ignored output the OutputStream
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
byte[]
to chars on a Writer
using the default character encoding of the platform.
This method uses String#String(byte[])
.
Parameters: data the byte array to write, do not modify during output,
null ignored output the Writer
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
byte[]
to chars on a Writer
using the specified character encoding.
Character encoding names can be found at IANA.
This method uses String#String(byte[], String)
.
Parameters: data the byte array to write, do not modify during output,
null ignored output the Writer
to write to encoding the encoding to use, null means platform default
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
char[]
to a Writer
using the default character encoding of the platform.
Parameters: data the char array to write, do not modify during output,
null ignored output the Writer
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
char[]
to bytes on an
OutputStream
.
This method uses String#String(char[])
and
String#getBytes().
Parameters: data the char array to write, do not modify during output,
null ignored output the OutputStream
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
char[]
to bytes on an
OutputStream
using the specified character encoding.
Character encoding names can be found at IANA.
This method uses String#String(char[])
and
String#getBytes(String).
Parameters: data the char array to write, do not modify during output,
null ignored output the OutputStream
to write to encoding the encoding to use, null means platform default
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
String
to a Writer
.
Parameters: data the String
to write, null ignored output the Writer
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
String
to bytes on an
OutputStream
using the default character encoding of the
platform.
This method uses String#getBytes().
Parameters: data the String
to write, null ignored output the OutputStream
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
String
to bytes on an
OutputStream
using the specified character encoding.
Character encoding names can be found at IANA.
This method uses String#getBytes(String).
Parameters: data the String
to write, null ignored output the OutputStream
to write to encoding the encoding to use, null means platform default
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
StringBuffer
to a Writer
.
Parameters: data the StringBuffer
to write, null ignored output the Writer
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
StringBuffer
to bytes on an
OutputStream
using the default character encoding of the
platform.
This method uses String#getBytes().
Parameters: data the StringBuffer
to write, null ignored output the OutputStream
to write to
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
StringBuffer
to bytes on an
OutputStream
using the specified character encoding.
Character encoding names can be found at IANA.
This method uses String#getBytes(String).
Parameters: data the StringBuffer
to write, null ignored output the OutputStream
to write to encoding the encoding to use, null means platform default
Throws: NullPointerException if output is null IOException if an I/O error occurs
Since: Commons IO 1.1
toString()
value of each item in a collection to
an OutputStream
line by line, using the default character
encoding of the platform and the specified line ending.
Parameters: lines the lines to write, null entries produce blank lines lineEnding the line separator to use, null is system default output the OutputStream
to write to, not null, not closed
Throws: NullPointerException if the output is null IOException if an I/O error occurs
Since: Commons IO 1.1
toString()
value of each item in a collection to
an OutputStream
line by line, using the specified character
encoding and the specified line ending.
Character encoding names can be found at IANA.
Parameters: lines the lines to write, null entries produce blank lines lineEnding the line separator to use, null is system default output the OutputStream
to write to, not null, not closed encoding the encoding to use, null means platform default
Throws: NullPointerException if the output is null IOException if an I/O error occurs
Since: Commons IO 1.1
toString()
value of each item in a collection to
a Writer
line by line, using the specified line ending.
Parameters: lines the lines to write, null entries produce blank lines lineEnding the line separator to use, null is system default writer the Writer
to write to, not null, not closed
Throws: NullPointerException if the input is null IOException if an I/O error occurs
Since: Commons IO 1.1