gov.lbl.dsd.p2pio.util.IOUtils
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java.lang.Object
General IO Stream manipulation.
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
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).
Behold, intrepid explorers; a map of this class:
Method Input Output Dependency
------ ----- ------ -------
1 copy InputStream OutputStream (primitive)
2 copy Reader Writer (primitive)
3 copy InputStream Writer 2
4 toString InputStream String 3
5 toByteArray InputStream byte[] 1
6 copy Reader OutputStream 2
7 toString Reader String 2
8 toByteArray Reader byte[] 6
9 copy String OutputStream 2
10 copy String Writer (trivial)
11 toByteArray String byte[] 9
12 copy byte[] Writer 3
13 toString byte[] String 12
14 copy byte[] OutputStream (trivial)
Note that only the first two methods shuffle bytes; the rest use these two, or (if possible) copy using native Java copy methods. As there are method variants to specify buffer size and encoding, each row may correspond to up to 4 methods.
Origin of code: Apache Avalon (Excalibur)
| Constructor Summary | |
IOUtils()
|
|
| Method Summary | |
static boolean |
contentEquals(InputStream input1,
InputStream input2)
Compare the contents of two Streams to determine if they are equal or not. |
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 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 int |
copy(InputStream input,
OutputStream output)
Copy bytes from an InputStream to an OutputStream. |
static int |
copy(InputStream input,
OutputStream output,
int bufferSize)
Copy bytes from an InputStream to an OutputStream. |
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 int |
copy(Reader input,
Writer output)
Copy chars from a Reader to a Writer. |
static int |
copy(Reader input,
Writer output,
int bufferSize)
Copy chars from a Reader to a Writer. |
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 |
shutdownReader(Reader input)
Unconditionally close an Reader. |
static void |
shutdownStream(InputStream input)
Unconditionally close an InputStream. |
static void |
shutdownStream(OutputStream output)
Unconditionally close an OutputStream. |
static void |
shutdownWriter(Writer output)
Unconditionally close an Writer. |
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(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. |
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. |
| Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
public IOUtils()
| Method Detail |
public static void shutdownReader(Reader input)
Reader.
Equivalent to Reader.close(), except any exceptions will be ignored.
input - A (possibly null) Readerpublic static void shutdownWriter(Writer output)
Writer.
Equivalent to Writer.close(), except any exceptions will be ignored.
output - A (possibly null) Writerpublic static void shutdownStream(OutputStream output)
OutputStream.
Equivalent to OutputStream.close(), except any exceptions will be ignored.
output - A (possibly null) OutputStreampublic static void shutdownStream(InputStream input)
InputStream.
Equivalent to InputStream.close(), except any exceptions will be ignored.
input - A (possibly null) InputStream
public static int copy(InputStream input,
OutputStream output)
throws IOException
InputStream to an OutputStream.
input - the InputStream to read fromoutput - the OutputStream to write to
IOException - In case of an I/O problem
public static int copy(InputStream input,
OutputStream output,
int bufferSize)
throws IOException
InputStream to an OutputStream.
input - the InputStream to read fromoutput - the OutputStream to write tobufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static int copy(Reader input,
Writer output)
throws IOException
Reader to a Writer.
input - the Reader to read fromoutput - the Writer to write to
IOException - In case of an I/O problem
public static int copy(Reader input,
Writer output,
int bufferSize)
throws IOException
Reader to a Writer.
input - the Reader to read fromoutput - the Writer to write tobufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static void copy(InputStream input,
Writer output)
throws IOException
InputStream to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
input - the InputStream to read fromoutput - the Writer to write to
IOException - In case of an I/O problem
public static void copy(InputStream input,
Writer output,
int bufferSize)
throws IOException
InputStream to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
input - the InputStream to read fromoutput - the Writer to write tobufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static void copy(InputStream input,
Writer output,
String encoding)
throws IOException
InputStream to chars on a
Writer, using the specified encoding.
input - the InputStream to read fromoutput - the Writer to write toencoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
IOException - In case of an I/O problem
public static void copy(InputStream input,
Writer output,
String encoding,
int bufferSize)
throws IOException
InputStream to chars on a
Writer, using the specified encoding.
input - the InputStream to read fromoutput - the Writer to write toencoding - 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.
IOException - In case of an I/O problem
public static String toString(InputStream input)
throws IOException
InputStream as a String.
The platform's default encoding is used for the byte-to-char conversion.
input - the InputStream to read from
String
IOException - In case of an I/O problem
public static String toString(InputStream input,
int bufferSize)
throws IOException
InputStream as a String.
The platform's default encoding is used for the byte-to-char conversion.
input - the InputStream to read frombufferSize - Size of internal buffer to use.
String
IOException - In case of an I/O problem
public static String toString(InputStream input,
String encoding)
throws IOException
InputStream as a String.
input - the InputStream to read fromencoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
String
IOException - In case of an I/O problem
public static String toString(InputStream input,
String encoding,
int bufferSize)
throws IOException
InputStream as a String.
input - the InputStream to read fromencoding - 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.
String
IOException - In case of an I/O problem
public static byte[] toByteArray(InputStream input)
throws IOException
InputStream as a byte[].
input - the InputStream to read from
IOException - In case of an I/O problem
public static byte[] toByteArray(InputStream input,
int bufferSize)
throws IOException
InputStream as a byte[].
input - the InputStream to read frombufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static void copy(Reader input,
OutputStream output)
throws IOException
Reader to bytes on an OutputStream, and
flush the OutputStream.
input - the Reader to read fromoutput - the OutputStream to write to
IOException - In case of an I/O problem
public static void copy(Reader input,
OutputStream output,
int bufferSize)
throws IOException
Reader to bytes on an OutputStream, and
flush the OutputStream.
input - the Reader to read fromoutput - the OutputStream to write tobufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static String toString(Reader input)
throws IOException
Reader as a String.
input - the Reader to read from
String
IOException - In case of an I/O problem
public static String toString(Reader input,
int bufferSize)
throws IOException
Reader as a String.
input - the Reader to read frombufferSize - Size of internal buffer to use.
String
IOException - In case of an I/O problem
public static byte[] toByteArray(Reader input)
throws IOException
Reader as a byte[].
input - the Reader to read from
IOException - In case of an I/O problem
public static byte[] toByteArray(Reader input,
int bufferSize)
throws IOException
Reader as a byte[].
input - the Reader to read frombufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static void copy(String input,
OutputStream output)
throws IOException
String to bytes on an OutputStream, and
flush the OutputStream.
input - the String to read fromoutput - the OutputStream to write to
IOException - In case of an I/O problem
public static void copy(String input,
OutputStream output,
int bufferSize)
throws IOException
String to bytes on an OutputStream, and
flush the OutputStream.
input - the String to read fromoutput - the OutputStream to write tobufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static void copy(String input,
Writer output)
throws IOException
String to a Writer.
input - the String to read fromoutput - the Writer to write to
IOException - In case of an I/O problem
public static byte[] toByteArray(String input)
throws IOException
String as a byte[].
input - the String to convert
IOException - In case of an I/O problem
public static byte[] toByteArray(String input,
int bufferSize)
throws IOException
String as a byte[].
input - the String to convertbufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static void copy(byte[] input,
Writer output)
throws IOException
byte[] to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
input - the byte array to read fromoutput - the Writer to write to
IOException - In case of an I/O problem
public static void copy(byte[] input,
Writer output,
int bufferSize)
throws IOException
byte[] to chars on a
Writer.
The platform's default encoding is used for the byte-to-char conversion.
input - the byte array to read fromoutput - the Writer to write tobufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static void copy(byte[] input,
Writer output,
String encoding)
throws IOException
byte[] to chars on a
Writer, using the specified encoding.
input - the byte array to read fromoutput - the Writer to write toencoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
IOException - In case of an I/O problem
public static void copy(byte[] input,
Writer output,
String encoding,
int bufferSize)
throws IOException
byte[] to chars on a
Writer, using the specified encoding.
input - the byte array to read fromoutput - the Writer to write toencoding - 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.
IOException - In case of an I/O problem
public static String toString(byte[] input)
throws IOException
byte[] as a String.
The platform's default encoding is used for the byte-to-char conversion.
input - the byte array to read from
String
IOException - In case of an I/O problem
public static String toString(byte[] input,
int bufferSize)
throws IOException
byte[] as a String.
The platform's default encoding is used for the byte-to-char conversion.
input - the byte array to read frombufferSize - Size of internal buffer to use.
String
IOException - In case of an I/O problem
public static String toString(byte[] input,
String encoding)
throws IOException
byte[] as a String.
input - the byte array to read fromencoding - The name of a supported character encoding. See the
IANA
Charset Registry for a list of valid encoding types.
String
IOException - In case of an I/O problem
public static String toString(byte[] input,
String encoding,
int bufferSize)
throws IOException
byte[] as a String.
input - the byte array to read fromencoding - 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.
String
IOException - In case of an I/O problem
public static void copy(byte[] input,
OutputStream output)
throws IOException
byte[] to an OutputStream.
input - the byte array to read fromoutput - the OutputStream to write to
IOException - In case of an I/O problem
public static void copy(byte[] input,
OutputStream output,
int bufferSize)
throws IOException
byte[] to an OutputStream.
input - the byte array to read fromoutput - the OutputStream to write tobufferSize - Size of internal buffer to use.
IOException - In case of an I/O problem
public static boolean contentEquals(InputStream input1,
InputStream input2)
throws IOException
input1 - the first streaminput2 - the second stream
IOException - In case of an I/O problem
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