public class IOUtils
extends java.lang.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.
限定符和类型 | 字段和说明 |
---|---|
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 java.lang.String |
LINE_SEPARATOR
The system line separator string.
|
static java.lang.String |
LINE_SEPARATOR_UNIX
The Unix line separator string.
|
static java.lang.String |
LINE_SEPARATOR_WINDOWS
The Windows line separator string.
|
构造器和说明 |
---|
IOUtils()
Instances should NOT be constructed in standard programming.
|
限定符和类型 | 方法和说明 |
---|---|
static void |
closeQuietly(java.io.InputStream input)
Unconditionally close an
InputStream . |
static void |
closeQuietly(java.io.OutputStream output)
Unconditionally close an
OutputStream . |
static void |
closeQuietly(java.io.Reader input)
Unconditionally close an
Reader . |
static void |
closeQuietly(java.io.Writer output)
Unconditionally close a
Writer . |
static boolean |
contentEquals(java.io.InputStream input1,
java.io.InputStream input2)
Compare the contents of two Streams to determine if they are equal or
not.
|
static boolean |
contentEquals(java.io.Reader input1,
java.io.Reader input2)
Compare the contents of two Readers to determine if they are equal or
not.
|
static int |
copy(java.io.InputStream input,
java.io.OutputStream output)
Copy bytes from an
InputStream to an
OutputStream . |
static void |
copy(java.io.InputStream input,
java.io.Writer output)
Copy bytes from an
InputStream to chars on a
Writer using the default character encoding of the platform. |
static void |
copy(java.io.InputStream input,
java.io.Writer output,
java.lang.String encoding)
Copy bytes from an
InputStream to chars on a
Writer using the specified character encoding. |
static void |
copy(java.io.Reader input,
java.io.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(java.io.Reader input,
java.io.OutputStream output,
java.lang.String encoding)
Copy chars from a
Reader to bytes on an
OutputStream using the specified character encoding, and
calling flush. |
static int |
copy(java.io.Reader input,
java.io.Writer output)
Copy chars from a
Reader to a Writer . |
static long |
copyLarge(java.io.InputStream input,
java.io.OutputStream output)
Copy bytes from a large (over 2GB)
InputStream to an
OutputStream . |
static long |
copyLarge(java.io.Reader input,
java.io.Writer output)
Copy chars from a large (over 2GB)
Reader to a Writer . |
static java.util.List |
readLines(java.io.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 java.util.List |
readLines(java.io.InputStream input,
java.lang.String encoding)
Get the contents of an
InputStream as a list of Strings,
one entry per line, using the specified character encoding. |
static java.util.List |
readLines(java.io.Reader input)
Get the contents of a
Reader as a list of Strings,
one entry per line. |
static byte[] |
toByteArray(java.lang.String input)
已过时。
Use
String.getBytes() |
static char[] |
toCharArray(java.io.InputStream is)
Get the contents of an
InputStream as a character array
using the default character encoding of the platform. |
static char[] |
toCharArray(java.io.InputStream is,
java.lang.String encoding)
Get the contents of an
InputStream as a character array
using the specified character encoding. |
static char[] |
toCharArray(java.io.Reader input)
Get the contents of a
Reader as a character array. |
static java.io.InputStream |
toInputStream(java.lang.String input)
Convert the specified string to an input stream, encoded as bytes
using the default character encoding of the platform.
|
static java.io.InputStream |
toInputStream(java.lang.String input,
java.lang.String encoding)
Convert the specified string to an input stream, encoded as bytes
using the specified character encoding.
|
static java.lang.String |
toString(byte[] input)
已过时。
Use
String.String(byte[]) |
static java.lang.String |
toString(byte[] input,
java.lang.String encoding)
已过时。
Use
String.String(byte[],String) |
static java.lang.String |
toString(java.io.InputStream input)
Get the contents of an
InputStream as a String
using the default character encoding of the platform. |
static java.lang.String |
toString(java.io.InputStream input,
java.lang.String encoding)
Get the contents of an
InputStream as a String
using the specified character encoding. |
static java.lang.String |
toString(java.io.Reader input)
Get the contents of a
Reader as a String. |
static void |
write(byte[] data,
java.io.OutputStream output)
Writes bytes from a
byte[] to an OutputStream . |
static void |
write(byte[] data,
java.io.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,
java.io.Writer output,
java.lang.String encoding)
Writes bytes from a
byte[] to chars on a Writer
using the specified character encoding. |
static void |
write(char[] data,
java.io.OutputStream output)
Writes chars from a
char[] to bytes on an
OutputStream . |
static void |
write(char[] data,
java.io.OutputStream output,
java.lang.String encoding)
Writes chars from a
char[] to bytes on an
OutputStream using the specified character encoding. |
static void |
write(char[] data,
java.io.Writer output)
Writes chars from a
char[] to a Writer
using the default character encoding of the platform. |
static void |
write(java.lang.StringBuffer data,
java.io.OutputStream output)
Writes chars from a
StringBuffer to bytes on an
OutputStream using the default character encoding of the
platform. |
static void |
write(java.lang.StringBuffer data,
java.io.OutputStream output,
java.lang.String encoding)
Writes chars from a
StringBuffer to bytes on an
OutputStream using the specified character encoding. |
static void |
write(java.lang.StringBuffer data,
java.io.Writer output)
Writes chars from a
StringBuffer to a Writer . |
static void |
write(java.lang.String data,
java.io.OutputStream output)
Writes chars from a
String to bytes on an
OutputStream using the default character encoding of the
platform. |
static void |
write(java.lang.String data,
java.io.OutputStream output,
java.lang.String encoding)
Writes chars from a
String to bytes on an
OutputStream using the specified character encoding. |
static void |
write(java.lang.String data,
java.io.Writer output)
Writes chars from a
String to a Writer . |
static void |
writeLines(java.util.Collection lines,
java.lang.String lineEnding,
java.io.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(java.util.Collection lines,
java.lang.String lineEnding,
java.io.OutputStream output,
java.lang.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(java.util.Collection lines,
java.lang.String lineEnding,
java.io.Writer writer)
Writes the
toString() value of each item in a collection to
a Writer line by line, using the specified line ending. |
public static final char DIR_SEPARATOR_UNIX
public static final char DIR_SEPARATOR_WINDOWS
public static final char DIR_SEPARATOR
public static final java.lang.String LINE_SEPARATOR_UNIX
public static final java.lang.String LINE_SEPARATOR_WINDOWS
public static final java.lang.String LINE_SEPARATOR
public static void closeQuietly(java.io.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(java.io.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(java.io.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(java.io.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(java.lang.String input) throws java.io.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 convertjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurs (never occurs)public static char[] toCharArray(java.io.InputStream is) throws java.io.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 fromjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static char[] toCharArray(java.io.InputStream is, java.lang.String encoding) throws java.io.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 defaultjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static char[] toCharArray(java.io.Reader input) throws java.io.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 fromjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static java.lang.String toString(java.io.InputStream input) throws java.io.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 fromjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static java.lang.String toString(java.io.InputStream input, java.lang.String encoding) throws java.io.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 defaultjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static java.lang.String toString(java.io.Reader input) throws java.io.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 fromjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static java.lang.String toString(byte[] input) throws java.io.IOException
String.String(byte[])
byte[]
as a String
using the default character encoding of the platform.input
- the byte array to read fromjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurs (never occurs)public static java.lang.String toString(byte[] input, java.lang.String encoding) throws java.io.IOException
String.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 defaultjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurs (never occurs)public static java.util.List readLines(java.io.InputStream input) throws java.io.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 nulljava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static java.util.List readLines(java.io.InputStream input, java.lang.String encoding) throws java.io.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 defaultjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static java.util.List readLines(java.io.Reader input) throws java.io.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 nulljava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static java.io.InputStream toInputStream(java.lang.String input)
input
- the string to convertpublic static java.io.InputStream toInputStream(java.lang.String input, java.lang.String encoding) throws java.io.IOException
Character encoding names can be found at IANA.
input
- the string to convertencoding
- the encoding to use, null means platform defaultjava.io.IOException
- if the encoding is invalidpublic static void write(byte[] data, java.io.OutputStream output) throws java.io.IOException
byte[]
to an OutputStream
.data
- the byte array to write, do not modify during output,
null ignoredoutput
- the OutputStream
to write tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(byte[] data, java.io.Writer output) throws java.io.IOException
byte[]
to chars on a Writer
using the default character encoding of the platform.
This method uses String.String(byte[])
.
data
- the byte array to write, do not modify during output,
null ignoredoutput
- the Writer
to write tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(byte[] data, java.io.Writer output, java.lang.String encoding) throws java.io.IOException
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)
.
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 defaultjava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(char[] data, java.io.Writer output) throws java.io.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 tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(char[] data, java.io.OutputStream output) throws java.io.IOException
char[]
to bytes on an
OutputStream
.
This method uses String.String(char[])
and
String.getBytes()
.
data
- the char array to write, do not modify during output,
null ignoredoutput
- the OutputStream
to write tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(char[] data, java.io.OutputStream output, java.lang.String encoding) throws java.io.IOException
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)
.
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 defaultjava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(java.lang.String data, java.io.Writer output) throws java.io.IOException
String
to a Writer
.data
- the String
to write, null ignoredoutput
- the Writer
to write tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(java.lang.String data, java.io.OutputStream output) throws java.io.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 tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(java.lang.String data, java.io.OutputStream output, java.lang.String encoding) throws java.io.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 defaultjava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(java.lang.StringBuffer data, java.io.Writer output) throws java.io.IOException
StringBuffer
to a Writer
.data
- the StringBuffer
to write, null ignoredoutput
- the Writer
to write tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(java.lang.StringBuffer data, java.io.OutputStream output) throws java.io.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 tojava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void write(java.lang.StringBuffer data, java.io.OutputStream output, java.lang.String encoding) throws java.io.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 defaultjava.lang.NullPointerException
- if output is nulljava.io.IOException
- if an I/O error occurspublic static void writeLines(java.util.Collection lines, java.lang.String lineEnding, java.io.OutputStream output) throws java.io.IOException
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.lines
- the lines to write, null entries produce blank lineslineEnding
- the line separator to use, null is system defaultoutput
- the OutputStream
to write to, not null, not closedjava.lang.NullPointerException
- if the output is nulljava.io.IOException
- if an I/O error occurspublic static void writeLines(java.util.Collection lines, java.lang.String lineEnding, java.io.OutputStream output, java.lang.String encoding) throws java.io.IOException
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.
lines
- the lines to write, null entries produce blank lineslineEnding
- the line separator to use, null is system defaultoutput
- the OutputStream
to write to, not null, not closedencoding
- the encoding to use, null means platform defaultjava.lang.NullPointerException
- if the output is nulljava.io.IOException
- if an I/O error occurspublic static void writeLines(java.util.Collection lines, java.lang.String lineEnding, java.io.Writer writer) throws java.io.IOException
toString()
value of each item in a collection to
a Writer
line by line, using the specified line ending.lines
- the lines to write, null entries produce blank lineslineEnding
- the line separator to use, null is system defaultwriter
- the Writer
to write to, not null, not closedjava.lang.NullPointerException
- if the input is nulljava.io.IOException
- if an I/O error occurspublic static int copy(java.io.InputStream input, java.io.OutputStream output) throws java.io.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 tojava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occursjava.lang.ArithmeticException
- if the byte count is too largepublic static long copyLarge(java.io.InputStream input, java.io.OutputStream output) throws java.io.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 tojava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occurspublic static void copy(java.io.InputStream input, java.io.Writer output) throws java.io.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 tojava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occurspublic static void copy(java.io.InputStream input, java.io.Writer output, java.lang.String encoding) throws java.io.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 defaultjava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occurspublic static int copy(java.io.Reader input, java.io.Writer output) throws java.io.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 tojava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occursjava.lang.ArithmeticException
- if the character count is too largepublic static long copyLarge(java.io.Reader input, java.io.Writer output) throws java.io.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 tojava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occurspublic static void copy(java.io.Reader input, java.io.OutputStream output) throws java.io.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 tojava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occurspublic static void copy(java.io.Reader input, java.io.OutputStream output, java.lang.String encoding) throws java.io.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 defaultjava.lang.NullPointerException
- if the input or output is nulljava.io.IOException
- if an I/O error occurspublic static boolean contentEquals(java.io.InputStream input1, java.io.InputStream input2) throws java.io.IOException
This method buffers the input internally using
BufferedInputStream
if they are not already buffered.
input1
- the first streaminput2
- the second streamjava.lang.NullPointerException
- if either input is nulljava.io.IOException
- if an I/O error occurspublic static boolean contentEquals(java.io.Reader input1, java.io.Reader input2) throws java.io.IOException
This method buffers the input internally using
BufferedReader
if they are not already buffered.
input1
- the first readerinput2
- the second readerjava.lang.NullPointerException
- if either input is nulljava.io.IOException
- if an I/O error occurs