Firefish 0.5.10

gov.lbl.dsd.p2pio.util
Class IOUtils

java.lang.Object
  extended bygov.lbl.dsd.p2pio.util.IOUtils

public final class IOUtils
extends 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)

Version:
CVS $Revision: 1.1 $ $Date: 2004/01/16 23:52:19 $

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

IOUtils

public IOUtils()
Method Detail

shutdownReader

public static void shutdownReader(Reader input)
Unconditionally close an Reader. Equivalent to Reader.close(), except any exceptions will be ignored.

Parameters:
input - A (possibly null) Reader

shutdownWriter

public static void shutdownWriter(Writer output)
Unconditionally close an Writer. Equivalent to Writer.close(), except any exceptions will be ignored.

Parameters:
output - A (possibly null) Writer

shutdownStream

public static void shutdownStream(OutputStream output)
Unconditionally close an OutputStream. Equivalent to OutputStream.close(), except any exceptions will be ignored.

Parameters:
output - A (possibly null) OutputStream

shutdownStream

public static void shutdownStream(InputStream input)
Unconditionally close an InputStream. Equivalent to InputStream.close(), except any exceptions will be ignored.

Parameters:
input - A (possibly null) InputStream

copy

public static int copy(InputStream input,
                       OutputStream output)
                throws IOException
Copy bytes from an InputStream to an OutputStream.

Parameters:
input - the InputStream to read from
output - the OutputStream to write to
Returns:
the number of bytes copied
Throws:
IOException - In case of an I/O problem

copy

public static int copy(InputStream input,
                       OutputStream output,
                       int bufferSize)
                throws IOException
Copy bytes from an InputStream to an OutputStream.

Parameters:
input - the InputStream to read from
output - the OutputStream to write to
bufferSize - Size of internal buffer to use.
Returns:
the number of bytes copied
Throws:
IOException - In case of an I/O problem

copy

public static int copy(Reader input,
                       Writer output)
                throws IOException
Copy chars from a Reader to a Writer.

Parameters:
input - the Reader to read from
output - the Writer to write to
Returns:
the number of characters copied
Throws:
IOException - In case of an I/O problem

copy

public static int copy(Reader input,
                       Writer output,
                       int bufferSize)
                throws IOException
Copy chars from a Reader to a Writer.

Parameters:
input - the Reader to read from
output - the Writer to write to
bufferSize - Size of internal buffer to use.
Returns:
the number of characters copied
Throws:
IOException - In case of an I/O problem

copy

public static void copy(InputStream input,
                        Writer output)
                 throws IOException
Copy and convert bytes from an InputStream to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the InputStream to read from
output - the Writer to write to
Throws:
IOException - In case of an I/O problem

copy

public static void copy(InputStream input,
                        Writer output,
                        int bufferSize)
                 throws IOException
Copy and convert bytes from an InputStream to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the InputStream to read from
output - the Writer to write to
bufferSize - Size of internal buffer to use.
Throws:
IOException - In case of an I/O problem

copy

public static void copy(InputStream input,
                        Writer output,
                        String encoding)
                 throws IOException
Copy and convert bytes from an InputStream to chars on a Writer, using the specified encoding.

Parameters:
input - the InputStream to read from
output - the Writer to write to
encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
Throws:
IOException - In case of an I/O problem

copy

public static void copy(InputStream input,
                        Writer output,
                        String encoding,
                        int bufferSize)
                 throws IOException
Copy and convert bytes from an InputStream to chars on a Writer, using the specified encoding.

Parameters:
input - the InputStream to read from
output - the Writer to write to
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.
Throws:
IOException - In case of an I/O problem

toString

public static String toString(InputStream input)
                       throws IOException
Get the contents of an InputStream as a String. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the InputStream to read from
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toString

public static String toString(InputStream input,
                              int bufferSize)
                       throws IOException
Get the contents of an InputStream as a String. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the InputStream to read from
bufferSize - Size of internal buffer to use.
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toString

public static String toString(InputStream input,
                              String encoding)
                       throws IOException
Get the contents of an InputStream as a String.

Parameters:
input - the InputStream to read from
encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toString

public static String toString(InputStream input,
                              String encoding,
                              int bufferSize)
                       throws IOException
Get the contents of an InputStream as a String.

Parameters:
input - the InputStream to read from
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.
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toByteArray

public static byte[] toByteArray(InputStream input)
                          throws IOException
Get the contents of an InputStream as a byte[].

Parameters:
input - the InputStream to read from
Returns:
the requested byte array
Throws:
IOException - In case of an I/O problem

toByteArray

public static byte[] toByteArray(InputStream input,
                                 int bufferSize)
                          throws IOException
Get the contents of an InputStream as a byte[].

Parameters:
input - the InputStream to read from
bufferSize - Size of internal buffer to use.
Returns:
the requested byte array
Throws:
IOException - In case of an I/O problem

copy

public static void copy(Reader input,
                        OutputStream output)
                 throws IOException
Serialize chars from a Reader to bytes on an OutputStream, and flush the OutputStream.

Parameters:
input - the Reader to read from
output - the OutputStream to write to
Throws:
IOException - In case of an I/O problem

copy

public static void copy(Reader input,
                        OutputStream output,
                        int bufferSize)
                 throws IOException
Serialize chars from a Reader to bytes on an OutputStream, and flush the OutputStream.

Parameters:
input - the Reader to read from
output - the OutputStream to write to
bufferSize - Size of internal buffer to use.
Throws:
IOException - In case of an I/O problem

toString

public static String toString(Reader input)
                       throws IOException
Get the contents of a Reader as a String.

Parameters:
input - the Reader to read from
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toString

public static String toString(Reader input,
                              int bufferSize)
                       throws IOException
Get the contents of a Reader as a String.

Parameters:
input - the Reader to read from
bufferSize - Size of internal buffer to use.
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toByteArray

public static byte[] toByteArray(Reader input)
                          throws IOException
Get the contents of a Reader as a byte[].

Parameters:
input - the Reader to read from
Returns:
the requested byte array
Throws:
IOException - In case of an I/O problem

toByteArray

public static byte[] toByteArray(Reader input,
                                 int bufferSize)
                          throws IOException
Get the contents of a Reader as a byte[].

Parameters:
input - the Reader to read from
bufferSize - Size of internal buffer to use.
Returns:
the requested byte array
Throws:
IOException - In case of an I/O problem

copy

public static void copy(String input,
                        OutputStream output)
                 throws IOException
Serialize chars from a String to bytes on an OutputStream, and flush the OutputStream.

Parameters:
input - the String to read from
output - the OutputStream to write to
Throws:
IOException - In case of an I/O problem

copy

public static void copy(String input,
                        OutputStream output,
                        int bufferSize)
                 throws IOException
Serialize chars from a String to bytes on an OutputStream, and flush the OutputStream.

Parameters:
input - the String to read from
output - the OutputStream to write to
bufferSize - Size of internal buffer to use.
Throws:
IOException - In case of an I/O problem

copy

public static void copy(String input,
                        Writer output)
                 throws IOException
Copy chars from a String to a Writer.

Parameters:
input - the String to read from
output - the Writer to write to
Throws:
IOException - In case of an I/O problem

toByteArray

public static byte[] toByteArray(String input)
                          throws IOException
Get the contents of a String as a byte[].

Parameters:
input - the String to convert
Returns:
the requested byte array
Throws:
IOException - In case of an I/O problem

toByteArray

public static byte[] toByteArray(String input,
                                 int bufferSize)
                          throws IOException
Get the contents of a String as a byte[].

Parameters:
input - the String to convert
bufferSize - Size of internal buffer to use.
Returns:
the requested byte array
Throws:
IOException - In case of an I/O problem

copy

public static void copy(byte[] input,
                        Writer output)
                 throws IOException
Copy and convert bytes from a byte[] to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the byte array to read from
output - the Writer to write to
Throws:
IOException - In case of an I/O problem

copy

public static void copy(byte[] input,
                        Writer output,
                        int bufferSize)
                 throws IOException
Copy and convert bytes from a byte[] to chars on a Writer. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the byte array to read from
output - the Writer to write to
bufferSize - Size of internal buffer to use.
Throws:
IOException - In case of an I/O problem

copy

public static void copy(byte[] input,
                        Writer output,
                        String encoding)
                 throws IOException
Copy and convert bytes from a byte[] to chars on a Writer, using the specified encoding.

Parameters:
input - the byte array to read from
output - the Writer to write to
encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
Throws:
IOException - In case of an I/O problem

copy

public static void copy(byte[] input,
                        Writer output,
                        String encoding,
                        int bufferSize)
                 throws IOException
Copy and convert bytes from a byte[] to chars on a Writer, using the specified encoding.

Parameters:
input - the byte array to read from
output - the Writer to write to
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.
Throws:
IOException - In case of an I/O problem

toString

public static String toString(byte[] input)
                       throws IOException
Get the contents of a byte[] as a String. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the byte array to read from
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toString

public static String toString(byte[] input,
                              int bufferSize)
                       throws IOException
Get the contents of a byte[] as a String. The platform's default encoding is used for the byte-to-char conversion.

Parameters:
input - the byte array to read from
bufferSize - Size of internal buffer to use.
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toString

public static String toString(byte[] input,
                              String encoding)
                       throws IOException
Get the contents of a byte[] as a String.

Parameters:
input - the byte array to read from
encoding - The name of a supported character encoding. See the IANA Charset Registry for a list of valid encoding types.
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

toString

public static String toString(byte[] input,
                              String encoding,
                              int bufferSize)
                       throws IOException
Get the contents of a byte[] as a String.

Parameters:
input - the byte array to read from
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.
Returns:
the requested String
Throws:
IOException - In case of an I/O problem

copy

public static void copy(byte[] input,
                        OutputStream output)
                 throws IOException
Copy bytes from a byte[] to an OutputStream.

Parameters:
input - the byte array to read from
output - the OutputStream to write to
Throws:
IOException - In case of an I/O problem

copy

public static void copy(byte[] input,
                        OutputStream output,
                        int bufferSize)
                 throws IOException
Copy bytes from a byte[] to an OutputStream.

Parameters:
input - the byte array to read from
output - the OutputStream to write to
bufferSize - Size of internal buffer to use.
Throws:
IOException - In case of an I/O problem

contentEquals

public static boolean contentEquals(InputStream input1,
                                    InputStream input2)
                             throws IOException
Compare the contents of two Streams to determine if they are equal or not.

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
Throws:
IOException - In case of an I/O problem

Firefish 0.5.10

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