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.
| Modifier and Type | Field and Description |
|---|---|
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 and Description |
|---|
IOUtils()
Instances should NOT be constructed in standard programming.
|
| Modifier and Type | Method and Description |
|---|---|
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 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 LineIterator |
lineIterator(Reader reader)
Return an Iterator for the lines in a
Reader. |
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 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(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.
|
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(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 |
write(StringBuffer data,
Writer output)
Writes chars from a
StringBuffer 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(String data,
Writer output)
Writes chars from a
String to a Writer. |
static void |
writeLines(Collection<String> 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<String> 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<String> 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. |
public static final char DIR_SEPARATOR_UNIX
public static final char DIR_SEPARATOR_WINDOWS
public static final char DIR_SEPARATOR
public static final String LINE_SEPARATOR_UNIX
public static final String LINE_SEPARATOR_WINDOWS
public static final String LINE_SEPARATOR
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(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 occurspublic 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 occurspublic static String toString(byte[] input) throws IOException
String.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)public static String toString(byte[] input, String encoding) throws 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 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 LineIterator lineIterator(Reader reader)
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 LineIterator.close() or
LineIterator.closeQuietly(LineIterator).
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 );
}
reader - the Reader to read from, not nullIllegalArgumentException - if the reader is nullpublic static LineIterator lineIterator(InputStream input, String encoding) throws IOException
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 LineIterator.close() or
LineIterator.closeQuietly(LineIterator).
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 );
}
input - the InputStream to read from, not nullencoding - the encoding to use, null means platform defaultIllegalArgumentException - if the input is nullIOException - if an I/O error occurs, such as 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.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.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.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.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(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 occurspublic 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 occurspublic 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 occurspublic 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 void writeLines(Collection<String> lines, String lineEnding, OutputStream output) throws 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 closedNullPointerException - if the output is nullIOException - if an I/O error occurspublic static void writeLines(Collection<String> lines, String lineEnding, OutputStream output, String encoding) throws 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 defaultNullPointerException - if the output is nullIOException - if an I/O error occurspublic static void writeLines(Collection<String> lines, String lineEnding, Writer writer) throws 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 closedNullPointerException - if the input 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 occursCopyright © 2016. All Rights Reserved.