Class CopyUtils
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 byte-to-char methods, a copy variant allows the encoding
to be selected (otherwise the platform default is used). We would like to
encourage you to always specify the encoding because relying on the platform
default can lead to unexpected results.
We don't provide special variants for the copy methods that
let you specify the buffer size because in modern VMs the impact on speed
seems to be minimal. We're using a default buffer size of 4 KB.
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 copy Reader OutputStream 2
5 copy String OutputStream 2
6 copy String Writer (trivial)
7 copy byte[] Writer 3
8 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 the encoding, each row may correspond to up to 2 methods.
Provenance: Excalibur.
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionstatic voidcopy(byte[] input, OutputStream output) Deprecated.Copies bytes from abyte[]to anOutputStream.static voidDeprecated.Usecopy(byte[], Writer, String)insteadstatic voidDeprecated.Copies and convert bytes from abyte[]to chars on aWriter, using the specified encoding.static intcopy(InputStream input, OutputStream output) Deprecated.Copies bytes from anInputStreamto anOutputStream.static voidcopy(InputStream input, Writer output) Deprecated.Usecopy(InputStream, Writer, String)insteadstatic voidcopy(InputStream input, Writer output, String encoding) Deprecated.Copies and convert bytes from anInputStreamto chars on aWriter, using the specified encoding.static voidcopy(Reader input, OutputStream output) Deprecated.Usecopy(Reader, OutputStream, String)insteadstatic voidcopy(Reader input, OutputStream output, String encoding) Deprecated.static intstatic voidcopy(String input, OutputStream output) Deprecated.Usecopy(String, OutputStream, String)insteadstatic voidcopy(String input, OutputStream output, String encoding) Deprecated.static void
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Constructor Details
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CopyUtils
Deprecated.TODO Make private in 3.0.Instances should NOT be constructed in standard programming.
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Method Details
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copy
Deprecated.Copies bytes from abyte[]to anOutputStream.- Parameters:
input- the byte array to read fromoutput- theOutputStreamto write to- Throws:
IOException- In case of an I/O problem
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copy
Deprecated.Usecopy(byte[], Writer, String)insteadCopies and convert bytes from abyte[]to chars on aWriter. The platform's default encoding is used for the byte-to-char conversion.- Parameters:
input- the byte array to read fromoutput- theWriterto write to- Throws:
IOException- In case of an I/O problem
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copy
Deprecated.Copies and convert bytes from abyte[]to chars on aWriter, using the specified encoding.- Parameters:
input- the byte array to read fromoutput- theWriterto write toencoding- 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
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copy
Deprecated.Copies bytes from anInputStreamto anOutputStream.- Parameters:
input- theInputStreamto read fromoutput- theOutputStreamto write to- Returns:
- the number of bytes copied
- Throws:
IOException- In case of an I/O problem
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copy
Deprecated.Usecopy(InputStream, Writer, String)insteadCopies and convert bytes from anInputStreamto chars on aWriter. The platform's default encoding is used for the byte-to-char conversion.- Parameters:
input- theInputStreamto read fromoutput- theWriterto write to- Throws:
IOException- In case of an I/O problem
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copy
Deprecated.Copies and convert bytes from anInputStreamto chars on aWriter, using the specified encoding.- Parameters:
input- theInputStreamto read fromoutput- theWriterto write toencoding- 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
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copy
Deprecated.Usecopy(Reader, OutputStream, String)insteadSerialize chars from aReaderto bytes on anOutputStream, and flush theOutputStream. Uses the default platform encoding.- Parameters:
input- theReaderto read fromoutput- theOutputStreamto write to- Throws:
IOException- In case of an I/O problem
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copy
Deprecated.- Parameters:
input- theReaderto read fromoutput- theOutputStreamto write toencoding- 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- Since:
- 2.5
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copy
Deprecated.- Parameters:
input- theReaderto read fromoutput- theWriterto write to- Returns:
- the number of characters copied
- Throws:
IOException- In case of an I/O problem
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copy
Deprecated.Usecopy(String, OutputStream, String)insteadSerialize chars from aStringto bytes on anOutputStream, and flush theOutputStream. Uses the platform default encoding.- Parameters:
input- theStringto read fromoutput- theOutputStreamto write to- Throws:
IOException- In case of an I/O problem
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copy
Deprecated.- Parameters:
input- theStringto read fromoutput- theOutputStreamto write toencoding- 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- Since:
- 2.5
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copy
Deprecated.- Parameters:
input- theStringto read fromoutput- theWriterto write to- Throws:
IOException- In case of an I/O problem
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