org.codehaus.plexus.util
public final class IOUtil extends Object
This class provides static utility methods for input/output operations, particularly buffered
copying between sources (InputStream
, Reader
, String
and
byte[]
) and destinations (OutputStream
, Writer
,
String
and byte[]
).
Unless otherwise noted, these copy
methods do not flush or close the
streams. Often, doing so would require making non-portable assumptions about the streams' origin
and further use. This means that both streams' close()
methods must be called after
copying. if one omits this step, then the stream resources (sockets, file descriptors) are
released when the associated Stream is garbage-collected. It is not a good idea to rely on this
mechanism. For a good overview of the distinction between "memory management" and "resource
management", see this
UnixReview article
For each copy
method, a variant is provided that allows the caller to specify the
buffer size (the default is 4k). As the buffer size can have a fairly large impact on speed, this
may be worth tweaking. Often "large buffer -> faster" does not hold, even for large data
transfers.
For byte-to-char methods, a copy
variant allows the encoding to be selected
(otherwise the platform default is used).
The copy
methods use an internal buffer when copying. It is therefore advisable
not to deliberately wrap the stream arguments to the copy
methods in
Buffered*
streams. For example, don't do the
following:
copy( new BufferedInputStream( in ), new BufferedOutputStream( out ) );
The rationale is as follows:
Imagine that an InputStream's read() is a very expensive operation, which would usually suggest
wrapping in a BufferedInputStream. The BufferedInputStream works by issuing infrequent
java.io.InputStream#read(byte[] b, int off, int len)
requests on the underlying InputStream, to
fill an internal buffer, from which further read
requests can inexpensively get
their data (until the buffer runs out).
However, the copy
methods do the same thing, keeping an internal buffer,
populated by InputStream#read(byte[] b, int off, int len)
requests. Having two buffers
(or three if the destination stream is also buffered) is pointless, and the unnecessary buffer
management hurts performance slightly (about 3%, according to some simple experiments).
Since: 4.0
Version: $Id: IOUtil.java 5958 2007-02-28 10:29:55Z olamy $
Field Summary | |
---|---|
static int | DEFAULT_BUFFER_SIZE |
Constructor Summary | |
---|---|
IOUtil()
Private constructor to prevent instantiation. |
Method Summary | |
---|---|
static void | bufferedCopy(InputStream input, OutputStream output)
Copy bytes from an InputStream to an
OutputStream , with buffering.
|
static void | close(InputStream inputStream)
Closes the input stream. |
static void | close(OutputStream outputStream)
Closes the output stream. |
static void | close(Reader reader)
Closes the reader. |
static void | close(Writer writer)
Closes the writer. |
static boolean | contentEquals(InputStream input1, InputStream input2)
Compare the contents of two Streams to determine if they are equal or not.
|
static void | copy(InputStream input, OutputStream output)
Copy bytes from an InputStream to an OutputStream . |
static void | copy(InputStream input, OutputStream output, int bufferSize)
Copy bytes from an InputStream to an OutputStream . |
static void | copy(Reader input, Writer output)
Copy chars from a Reader to a Writer . |
static void | copy(Reader input, Writer output, int bufferSize)
Copy chars from a Reader to a Writer . |
static void | copy(InputStream input, Writer output)
Copy and convert bytes from an InputStream to chars on a
Writer .
|
static void | copy(InputStream input, Writer output, int bufferSize)
Copy and convert bytes from an InputStream to chars on a
Writer .
|
static void | copy(InputStream input, Writer output, String encoding)
Copy and convert bytes from an InputStream to chars on a
Writer , using the specified encoding. |
static void | copy(InputStream input, Writer output, String encoding, int bufferSize)
Copy and convert bytes from an InputStream to chars on a
Writer , using the specified encoding. |
static void | copy(Reader input, OutputStream output)
Serialize chars from a Reader to bytes on an OutputStream , and
flush the OutputStream . |
static void | copy(Reader input, OutputStream output, int bufferSize)
Serialize chars from a Reader to bytes on an OutputStream , and
flush the OutputStream . |
static void | copy(String input, OutputStream output)
Serialize chars from a String to bytes on an OutputStream , and
flush the OutputStream . |
static void | copy(String input, OutputStream output, int bufferSize)
Serialize chars from a String to bytes on an OutputStream , and
flush the OutputStream . |
static void | copy(String input, Writer output)
Copy chars from a String to a Writer . |
static void | copy(byte[] input, Writer output)
Copy and convert bytes from a byte[] to chars on a
Writer .
|
static void | copy(byte[] input, Writer output, int bufferSize)
Copy and convert bytes from a byte[] to chars on a
Writer .
|
static void | copy(byte[] input, Writer output, String encoding)
Copy and convert bytes from a byte[] to chars on a
Writer , using the specified encoding. |
static void | copy(byte[] input, Writer output, String encoding, int bufferSize)
Copy and convert bytes from a byte[] to chars on a
Writer , using the specified encoding. |
static void | copy(byte[] input, OutputStream output)
Copy bytes from a byte[] to an OutputStream . |
static void | copy(byte[] input, OutputStream output, int bufferSize)
Copy bytes from a byte[] to an OutputStream . |
static byte[] | toByteArray(InputStream input)
Get the contents of an InputStream as a byte[] . |
static byte[] | toByteArray(InputStream input, int bufferSize)
Get the contents of an InputStream as a byte[] . |
static byte[] | toByteArray(Reader input)
Get the contents of a Reader as a byte[] . |
static byte[] | toByteArray(Reader input, int bufferSize)
Get the contents of a Reader as a byte[] . |
static byte[] | toByteArray(String input)
Get the contents of a String as a byte[] . |
static byte[] | toByteArray(String input, int bufferSize)
Get the contents of a String as a byte[] . |
static String | toString(InputStream input)
Get the contents of an InputStream as a String.
|
static String | toString(InputStream input, int bufferSize)
Get the contents of an InputStream as a String.
|
static String | toString(InputStream input, String encoding)
Get the contents of an InputStream as a String. |
static String | toString(InputStream input, String encoding, int bufferSize)
Get the contents of an InputStream as a String. |
static String | toString(Reader input)
Get the contents of a Reader as a String. |
static String | toString(Reader input, int bufferSize)
Get the contents of a Reader as a String. |
static String | toString(byte[] input)
Get the contents of a byte[] as a String.
|
static String | toString(byte[] input, int bufferSize)
Get the contents of a byte[] as a String.
|
static String | toString(byte[] input, String encoding)
Get the contents of a byte[] as a String. |
static String | toString(byte[] input, String encoding, int bufferSize)
Get the contents of a byte[] as a String. |
Deprecated: Buffering streams is actively harmful! See the class description as to why. Use IOUtil instead.
Copy bytes from anInputStream
to an
OutputStream
, with buffering.
This is equivalent to passing a
java.io.BufferedInputStream and
java.io.BufferedOutputStream to IOUtil,
and flushing the output stream afterwards. The streams are not closed
after the copy.Parameters: inputStream The stream to close.
Parameters: outputStream The stream to close.
Parameters: reader The reader to close.
Parameters: wrtier The writer to close.
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
InputStream
to an OutputStream
.InputStream
to an OutputStream
.Parameters: bufferSize Size of internal buffer to use.
Reader
to a Writer
.Reader
to a Writer
.Parameters: bufferSize Size of internal buffer to use.
InputStream
to chars on a
Writer
.
The platform's default encoding is used for the byte-to-char conversion.InputStream
to chars on a
Writer
.
The platform's default encoding is used for the byte-to-char conversion.Parameters: bufferSize Size of internal buffer to use.
InputStream
to chars on a
Writer
, using the specified encoding.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
InputStream
to chars on a
Writer
, using the specified encoding.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types. bufferSize Size of internal buffer to use.
Reader
to bytes on an OutputStream
, and
flush the OutputStream
.Reader
to bytes on an OutputStream
, and
flush the OutputStream
.Parameters: bufferSize Size of internal buffer to use.
String
to bytes on an OutputStream
, and
flush the OutputStream
.String
to bytes on an OutputStream
, and
flush the OutputStream
.Parameters: bufferSize Size of internal buffer to use.
String
to a Writer
.byte[]
to chars on a
Writer
.
The platform's default encoding is used for the byte-to-char conversion.byte[]
to chars on a
Writer
.
The platform's default encoding is used for the byte-to-char conversion.Parameters: bufferSize Size of internal buffer to use.
byte[]
to chars on a
Writer
, using the specified encoding.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
byte[]
to chars on a
Writer
, using the specified encoding.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types. bufferSize Size of internal buffer to use.
byte[]
to an OutputStream
.byte[]
to an OutputStream
.Parameters: bufferSize Size of internal buffer to use.
InputStream
as a byte[]
.InputStream
as a byte[]
.Parameters: bufferSize Size of internal buffer to use.
Reader
as a byte[]
.Reader
as a byte[]
.Parameters: bufferSize Size of internal buffer to use.
String
as a byte[]
.String
as a byte[]
.Parameters: bufferSize Size of internal buffer to use.
InputStream
as a String.
The platform's default encoding is used for the byte-to-char conversion.InputStream
as a String.
The platform's default encoding is used for the byte-to-char conversion.Parameters: bufferSize Size of internal buffer to use.
InputStream
as a String.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
InputStream
as a String.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types. bufferSize Size of internal buffer to use.
Reader
as a String.Reader
as a String.Parameters: bufferSize Size of internal buffer to use.
byte[]
as a String.
The platform's default encoding is used for the byte-to-char conversion.byte[]
as a String.
The platform's default encoding is used for the byte-to-char conversion.Parameters: bufferSize Size of internal buffer to use.
byte[]
as a String.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
byte[]
as a String.Parameters: encoding The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types. bufferSize Size of internal buffer to use.