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.
Constructor and Description |
---|
IOUtils()
Instances should NOT be constructed in standard programming.
|
Modifier and Type | Method and Description |
---|---|
static void |
closeQuietly(Channel channel)
Unconditionally close a
Channel . |
static void |
closeQuietly(InputStream input)
Unconditionally close an
InputStream . |
static void |
closeQuietly(OutputStream output)
Unconditionally close an
OutputStream . |
static void |
closeQuietly(Reader input)
Unconditionally close an
Reader . |
static void |
closeQuietly(Writer output)
Unconditionally close a
Writer . |
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 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 int |
copy(Reader input,
Writer output)
Copy chars from a
Reader to a Writer . |
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 int |
read(InputStream input,
byte[] buffer,
int offset,
int length)
Reads bytes from an input stream.
|
static List<String> |
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<String> |
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<String> |
readLines(Reader input)
Get the contents of a
Reader as a list of Strings,
one entry per line. |
static long |
skip(InputStream input,
long toSkip)
Skips bytes from an input byte stream.
|
static long |
skip(InputStream input,
long toSkip,
byte[] buffer) |
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)
Deprecated.
|
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(CharSequence input)
Convert the specified CharSequence to an input stream, encoded as bytes
using the default character encoding of the platform.
|
static InputStream |
toInputStream(CharSequence input,
String encoding)
Convert the specified CharSequence to an input stream, encoded as bytes
using the specified character encoding.
|
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(byte[] input)
Deprecated.
Use
String(byte[]) |
static String |
toString(byte[] input,
String encoding)
Deprecated.
|
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 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,
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(char[] data,
Writer output)
Writes chars from a
char[] to a Writer
using the default character encoding of the platform. |
static void |
write(CharSequence data,
OutputStream output)
Writes chars from a
CharSequence to bytes on an
OutputStream using the default character encoding of the
platform. |
static void |
write(CharSequence data,
OutputStream output,
String encoding)
Writes chars from a
CharSequence to bytes on an
OutputStream using the specified character encoding. |
static void |
write(CharSequence data,
Writer output)
Writes chars from a
CharSequence to a Writer . |
static void |
write(StringBuffer data,
OutputStream output)
Deprecated.
replaced by write(CharSequence, OutputStream)
|
static void |
write(StringBuffer data,
OutputStream output,
String encoding)
Deprecated.
replaced by write(CharSequence, OutputStream, String)
|
static void |
write(StringBuffer data,
Writer output)
Deprecated.
replaced by write(CharSequence, 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(String data,
Writer output)
Writes chars from a
String to a Writer . |
public static final Charset UTF_8
public IOUtils()
public static void closeQuietly(Reader input)
Reader
.
Equivalent to Reader.close()
, except any exceptions will be ignored.
This is typically used in finally blocks.
input
- the Reader to close, may be null or already closedpublic static void closeQuietly(Channel channel)
Channel
.
Equivalent to Channel.close()
, except any exceptions will be ignored.
This is typically used in finally blocks.
channel
- the Channel to close, may be null or already closedpublic static void closeQuietly(Writer output)
Writer
.
Equivalent to Writer.close()
, except any exceptions will be ignored.
This is typically used in finally blocks.
output
- the Writer to close, may be null or already closedpublic static void closeQuietly(InputStream input)
InputStream
.
Equivalent to InputStream.close()
, except any exceptions will be ignored.
This is typically used in finally blocks.
input
- the InputStream to close, may be null or already closedpublic static void closeQuietly(OutputStream output)
OutputStream
.
Equivalent to OutputStream.close()
, except any exceptions will be ignored.
This is typically used in finally blocks.
output
- the OutputStream to close, may be null or already closedpublic static byte[] toByteArray(InputStream input) throws IOException
InputStream
as a byte[]
.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
input
- the InputStream
to read fromNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static byte[] toByteArray(Reader input) throws IOException
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
.
input
- the Reader
to read fromNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static byte[] toByteArray(Reader input, String encoding) throws IOException
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
.
input
- the Reader
to read fromencoding
- the encoding to use, null means platform defaultNullPointerException
- if the input is nullIOException
- if an I/O error occurs@Deprecated public static byte[] toByteArray(String input) throws IOException
String.getBytes()
String
as a byte[]
using the default character encoding of the platform.
This is the same as String.getBytes()
.
input
- the String
to convertNullPointerException
- if the input is nullIOException
- if an I/O error occurs (never occurs)public static char[] toCharArray(InputStream is) throws IOException
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
.
is
- the InputStream
to read fromNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static char[] toCharArray(InputStream is, String encoding) throws IOException
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
.
is
- the InputStream
to read fromencoding
- the encoding to use, null means platform defaultNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static char[] toCharArray(Reader input) throws IOException
Reader
as a character array.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
input
- the Reader
to read fromNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static String toString(InputStream input) throws IOException
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
.
input
- the InputStream
to read fromNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static String toString(InputStream input, String encoding) throws IOException
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
.
input
- the InputStream
to read fromencoding
- the encoding to use, null means platform defaultNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static String toString(Reader input) throws IOException
Reader
as a String.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
input
- the Reader
to read fromNullPointerException
- if the input is nullIOException
- if an I/O error occurs@Deprecated public static String toString(byte[] input) throws IOException
String(byte[])
byte[]
as a String
using the default character encoding of the platform.input
- the byte array to read fromNullPointerException
- if the input is nullIOException
- if an I/O error occurs (never occurs)@Deprecated public static String toString(byte[] input, String encoding) throws IOException
String(byte[],String)
byte[]
as a String
using the specified character encoding.
Character encoding names can be found at IANA.
input
- the byte array to read fromencoding
- the encoding to use, null means platform defaultNullPointerException
- if the input is nullIOException
- if an I/O error occurs (never occurs)public static List<String> readLines(InputStream input) throws IOException
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
.
input
- the InputStream
to read from, not nullNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static List<String> readLines(InputStream input, String encoding) throws IOException
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
.
input
- the InputStream
to read from, not nullencoding
- the encoding to use, null means platform defaultNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static List<String> readLines(Reader input) throws IOException
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
.
input
- the Reader
to read from, not nullNullPointerException
- if the input is nullIOException
- if an I/O error occurspublic static InputStream toInputStream(CharSequence input)
input
- the CharSequence to convertpublic static InputStream toInputStream(CharSequence input, String encoding) throws IOException
Character encoding names can be found at IANA.
input
- the CharSequence to convertencoding
- the encoding to use, null means platform defaultIOException
- if the encoding is invalidpublic static InputStream toInputStream(String input)
input
- the string to convertpublic static InputStream toInputStream(String input, String encoding) throws IOException
Character encoding names can be found at IANA.
input
- the string to convertencoding
- the encoding to use, null means platform defaultIOException
- if the encoding is invalidpublic static void write(byte[] data, OutputStream output) throws IOException
byte[]
to an OutputStream
.data
- the byte array to write, do not modify during output,
null ignoredoutput
- the OutputStream
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(byte[] data, Writer output) throws IOException
byte[]
to chars on a Writer
using the default character encoding of the platform.
This method uses String(byte[])
.
data
- the byte array to write, do not modify during output,
null ignoredoutput
- the Writer
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(byte[] data, Writer output, String encoding) throws IOException
byte[]
to chars on a Writer
using the specified character encoding.
Character encoding names can be found at IANA.
This method uses String(byte[], String)
.
data
- the byte array to write, do not modify during output,
null ignoredoutput
- the Writer
to write toencoding
- the encoding to use, null means platform defaultNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(char[] data, Writer output) throws IOException
char[]
to a Writer
using the default character encoding of the platform.data
- the char array to write, do not modify during output,
null ignoredoutput
- the Writer
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(char[] data, OutputStream output) throws IOException
char[]
to bytes on an
OutputStream
.
This method uses String(char[])
and
String.getBytes()
.
data
- the char array to write, do not modify during output,
null ignoredoutput
- the OutputStream
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(char[] data, OutputStream output, String encoding) throws IOException
char[]
to bytes on an
OutputStream
using the specified character encoding.
Character encoding names can be found at IANA.
This method uses String(char[])
and
String.getBytes(String)
.
data
- the char array to write, do not modify during output,
null ignoredoutput
- the OutputStream
to write toencoding
- the encoding to use, null means platform defaultNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(CharSequence data, Writer output) throws IOException
CharSequence
to a Writer
.data
- the CharSequence
to write, null ignoredoutput
- the Writer
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(CharSequence data, OutputStream output) throws IOException
CharSequence
to bytes on an
OutputStream
using the default character encoding of the
platform.
This method uses String.getBytes()
.
data
- the CharSequence
to write, null ignoredoutput
- the OutputStream
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(CharSequence data, OutputStream output, String encoding) throws IOException
CharSequence
to bytes on an
OutputStream
using the specified character encoding.
Character encoding names can be found at IANA.
This method uses String.getBytes(String)
.
data
- the CharSequence
to write, null ignoredoutput
- the OutputStream
to write toencoding
- the encoding to use, null means platform defaultNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(String data, Writer output) throws IOException
String
to a Writer
.data
- the String
to write, null ignoredoutput
- the Writer
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(String data, OutputStream output) throws IOException
String
to bytes on an
OutputStream
using the default character encoding of the
platform.
This method uses String.getBytes()
.
data
- the String
to write, null ignoredoutput
- the OutputStream
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static void write(String data, OutputStream output, String encoding) throws IOException
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)
.
data
- the String
to write, null ignoredoutput
- the OutputStream
to write toencoding
- the encoding to use, null means platform defaultNullPointerException
- if output is nullIOException
- if an I/O error occurs@Deprecated public static void write(StringBuffer data, Writer output) throws IOException
StringBuffer
to a Writer
.data
- the StringBuffer
to write, null ignoredoutput
- the Writer
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurs@Deprecated public static void write(StringBuffer data, OutputStream output) throws IOException
StringBuffer
to bytes on an
OutputStream
using the default character encoding of the
platform.
This method uses String.getBytes()
.
data
- the StringBuffer
to write, null ignoredoutput
- the OutputStream
to write toNullPointerException
- if output is nullIOException
- if an I/O error occurs@Deprecated public static void write(StringBuffer data, OutputStream output, String encoding) throws IOException
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)
.
data
- the StringBuffer
to write, null ignoredoutput
- the OutputStream
to write toencoding
- the encoding to use, null means platform defaultNullPointerException
- if output is nullIOException
- if an I/O error occurspublic static int copy(InputStream input, OutputStream output) throws IOException
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.
input
- the InputStream
to read fromoutput
- the OutputStream
to write toNullPointerException
- if the input or output is nullIOException
- if an I/O error occursArithmeticException
- if the byte count is too largepublic static long copyLarge(InputStream input, OutputStream output) throws IOException
InputStream
to an
OutputStream
.
This method buffers the input internally, so there is no need to use a
BufferedInputStream
.
input
- the InputStream
to read fromoutput
- the OutputStream
to write toNullPointerException
- if the input or output is nullIOException
- if an I/O error occurspublic static void copy(InputStream input, Writer output) throws IOException
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
.
input
- the InputStream
to read fromoutput
- the Writer
to write toNullPointerException
- if the input or output is nullIOException
- if an I/O error occurspublic static void copy(InputStream input, Writer output, String encoding) throws IOException
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
.
input
- the InputStream
to read fromoutput
- the Writer
to write toencoding
- the encoding to use, null means platform defaultNullPointerException
- if the input or output is nullIOException
- if an I/O error occurspublic static int copy(Reader input, Writer output) throws IOException
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.
input
- the Reader
to read fromoutput
- the Writer
to write toNullPointerException
- if the input or output is nullIOException
- if an I/O error occursArithmeticException
- if the character count is too largepublic static long copyLarge(Reader input, Writer output) throws IOException
Reader
to a Writer
.
This method buffers the input internally, so there is no need to use a
BufferedReader
.
input
- the Reader
to read fromoutput
- the Writer
to write toNullPointerException
- if the input or output is nullIOException
- if an I/O error occurspublic static void copy(Reader input, OutputStream output) throws IOException
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
.
input
- the Reader
to read fromoutput
- the OutputStream
to write toNullPointerException
- if the input or output is nullIOException
- if an I/O error occurspublic static void copy(Reader input, OutputStream output, String encoding) throws IOException
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
.
input
- the Reader
to read fromoutput
- the OutputStream
to write toencoding
- the encoding to use, null means platform defaultNullPointerException
- if the input or output is nullIOException
- if an I/O error occurspublic static boolean contentEquals(InputStream input1, InputStream input2) throws IOException
This method buffers the input internally using
BufferedInputStream
if they are not already buffered.
input1
- the first streaminput2
- the second streamNullPointerException
- if either input is nullIOException
- if an I/O error occurspublic static boolean contentEquals(Reader input1, Reader input2) throws IOException
This method buffers the input internally using
BufferedReader
if they are not already buffered.
input1
- the first readerinput2
- the second readerNullPointerException
- if either input is nullIOException
- if an I/O error occurspublic static int read(InputStream input, byte[] buffer, int offset, int length) throws IOException
InputStream
.input
- where to read input frombuffer
- destinationoffset
- initial offset into bufferlength
- length to read, must be >= 0IOException
- if a read error occurspublic static long skip(InputStream input, long toSkip) throws IOException
InputStream
.
Note that the implementation uses InputStream.read(byte[], int, int)
rather
than delegating to InputStream.skip(long)
.
This means that the method may be considerably less efficient than using the actual skip implementation,
this is done to guarantee that the correct number of bytes are skipped.
input
- byte stream to skiptoSkip
- number of bytes to skip.IOException
- if there is a problem reading the fileIllegalArgumentException
- if toSkip is negativeInputStream.skip(long)
,
IO-203 - Add skipFully() method for InputStreamspublic static long skip(InputStream input, long toSkip, byte[] buffer) throws IOException
IOException
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