| java.lang.Object | |
| ↳ | java.nio.charset.CharsetEncoder |
Transforms a sequence of 16-bit Java characters to a byte sequence in some encoding.
The input character sequence is a CharBuffer and the
output byte sequence is a ByteBuffer.
Use encode(CharBuffer) to encode an entire CharBuffer to a
new ByteBuffer, or encode(CharBuffer, ByteBuffer, boolean) for more
control. When using the latter method, the entire operation proceeds as follows:
Developers
reset() to reset the encoder if this instance has been used before.encode with the endOfInput
parameter set to false until additional input is not needed (as signaled by the return value).
The input buffer must be filled and the output buffer must be flushed between invocations.
The encode method will
convert as many characters as possible, and the process won't stop until the
input buffer has been exhausted, the output buffer has been filled, or an
error has occurred. A CoderResult instance will be
returned to indicate the current state. The caller should fill the input buffer, flush
the output buffer, or recovering from an error and try again, accordingly.
encode for the last time with
endOfInput set to true.flush(ByteBuffer) to flush remaining output.There are two classes of encoding error: malformed input signifies that the input character sequence is not legal, while unmappable character signifies that the input is legal but cannot be mapped to a byte sequence (because the charset cannot represent the character, for example).
Errors can be handled in three ways. The default is to
report the error to the caller. The alternatives are to
ignore the error or replace
the problematic input with the byte sequence returned by replacement(). The disposition
for each of the two kinds of error can be set independently using the onMalformedInput(CodingErrorAction)
and onUnmappableCharacter(CodingErrorAction) methods.
The default replacement bytes depend on the charset but can be overridden using the
replaceWith(byte[]) method.
This class is abstract and encapsulates many common operations of the
encoding process for all charsets. Encoders for a specific charset should
extend this class and need only to implement the
encodeLoop method for basic
encoding. If a subclass maintains internal state, it should also override the
implFlush and implReset methods.
This class is not thread-safe.
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Constructs a new
CharsetEncoder using the given parameters and
the replacement byte array { (byte) '?' }.
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Constructs a new
CharsetEncoder using the given
Charset, replacement byte array, average number and
maximum number of bytes created by this encoder for one input character.
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| Public Methods | |||||||||||
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Returns the average number of bytes created by this encoder for a single
input character.
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Tests whether the given
CharSequence can be encoded by this
encoder.
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Tests whether the given character can be encoded by this encoder.
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Returns the
Charset which this encoder uses.
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This is a facade method for the encoding operation.
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Encodes characters starting at the current position of the given input
buffer, and writes the equivalent byte sequence into the given output
buffer from its current position.
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Flushes this encoder.
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Tests whether the given argument is legal as this encoder's replacement byte
array.
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Returns this encoder's
CodingErrorAction when a malformed
input error occurred during the encoding process.
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Returns the maximum number of bytes which can be created by this encoder for
one input character, must be positive.
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Sets this encoder's action on malformed input error.
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Sets this encoder's action on unmappable character error.
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Sets the new replacement value.
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Returns the replacement byte array, which is never null or empty.
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Resets this encoder.
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Returns this encoder's
CodingErrorAction when unmappable
character occurred during encoding process.
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| Protected Methods | |||||||||||
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Encodes characters into bytes.
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Flushes this encoder.
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Notifies that this encoder's
CodingErrorAction specified
for malformed input error has been changed.
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Notifies that this encoder's
CodingErrorAction specified
for unmappable character error has been changed.
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Notifies that this encoder's replacement has been changed.
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Resets this encoder's charset related state.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
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Constructs a new CharsetEncoder using the given parameters and
the replacement byte array { (byte) '?' }.
Constructs a new CharsetEncoder using the given
Charset, replacement byte array, average number and
maximum number of bytes created by this encoder for one input character.
| cs | the Charset to be used by this encoder. |
|---|---|
| averageBytesPerChar | average number of bytes created by this encoder for one single input character, must be positive. |
| maxBytesPerChar | maximum number of bytes which can be created by this encoder for one single input character, must be positive. |
| replacement | the replacement byte array, cannot be null or empty, its
length cannot be larger than maxBytesPerChar,
and must be a legal replacement, which can be justified by
isLegalReplacement. |
| IllegalArgumentException | if any parameters are invalid. |
|---|
Returns the average number of bytes created by this encoder for a single input character.
Tests whether the given CharSequence can be encoded by this
encoder.
Note that this method may change the internal state of this encoder, so
it should not be called when another encode process is ongoing, otherwise
it will throw an IllegalStateException.
| IllegalStateException | if another encode process is ongoing. |
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Tests whether the given character can be encoded by this encoder.
Note that this method may change the internal state of this encoder, so
it should not be called when another encoding process is ongoing,
otherwise it will throw an IllegalStateException.
| IllegalStateException | if another encode process is ongoing. |
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This is a facade method for the encoding operation.
This method encodes the remaining character sequence of the given character buffer into a new byte buffer. This method performs a complete encoding operation, resets at first, then encodes, and flushes at last.
This method should not be invoked if another encode operation is ongoing.
| in | the input buffer. |
|---|
ByteBuffer containing the bytes produced by
this encoding operation. The buffer's limit will be the position
of the last byte in the buffer, and the position will be zero.| IllegalStateException | if another encoding operation is ongoing. |
|---|---|
| MalformedInputException | if an illegal input character sequence for this charset is
encountered, and the action for malformed error is
CodingErrorAction.REPORT |
| UnmappableCharacterException | if a legal but unmappable input character sequence for this
charset is encountered, and the action for unmappable
character error is
CodingErrorAction.REPORT.
Unmappable means the Unicode character sequence at the input
buffer's current position cannot be mapped to a equivalent
byte sequence. |
| CharacterCodingException | if other exception happened during the encode operation. |
Encodes characters starting at the current position of the given input buffer, and writes the equivalent byte sequence into the given output buffer from its current position.
The buffers' position will be changed with the reading and writing operation, but their limits and marks will be kept intact.
A CoderResult instance will be returned according to
following rules:
malformed input result
indicates that some malformed input error was encountered, and the
erroneous characters start at the input buffer's position and their
number can be got by result's length. This
kind of result can be returned only if the malformed action is
CodingErrorAction.REPORT.CoderResult.UNDERFLOW indicates that
as many characters as possible in the input buffer have been encoded. If
there is no further input and no characters left in the input buffer then
this task is complete. If this is not the case then the client should
call this method again supplying some more input characters.CoderResult.OVERFLOW indicates that the
output buffer has been filled, while there are still some characters
remaining in the input buffer. This method should be invoked again with a
non-full output buffer.unmappable character
result indicates that some unmappable character error was encountered,
and the erroneous characters start at the input buffer's position and
their number can be got by result's length.
This kind of result can be returned only on
CodingErrorAction.REPORT.
The endOfInput parameter indicates if the invoker can
provider further input. This parameter is true if and only if the
characters in the current input buffer are all inputs for this encoding
operation. Note that it is common and won't cause an error if the invoker
sets false and then has no more input available, while it may cause an
error if the invoker always sets true in several consecutive invocations.
This would make the remaining input to be treated as malformed input.
input.
This method invokes the
encodeLoop method to
implement the basic encode logic for a specific charset.
| in | the input buffer. |
|---|---|
| out | the output buffer. |
| endOfInput | true if all the input characters have been provided. |
CoderResult instance indicating the result.| IllegalStateException | if the encoding operation has already started or no more input is needed in this encoding process. |
|---|---|
| CoderMalfunctionError | If the encodeLoop
method threw an BufferUnderflowException or
BufferUnderflowException.
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Flushes this encoder.
This method will call implFlush. Some
encoders may need to write some bytes to the output buffer when they have
read all input characters. Subclasses can override
implFlush to perform any writes that are
required at the end of the output sequence, such as footers and other
metadata.
The maximum number of written bytes won't be larger than
out.remaining(). If the encoder wants to
write more bytes than the output buffer's available remaining space, then
it will return CoderResult.OVERFLOW. This method must then be
called again with a byte buffer that has free space.
If the encoder was asked to flush its output when its input is incomplete,
(because it ends with an unpaired surrogate, say) it may return
CodeResult.MALFORMED.
In all other cases the encoder will return CoderResult.UNDERFLOW,
which signifies that all the input so far has been successfully encoded.
During the flush, the output buffer's position will be changed accordingly, while its mark and limit will be intact.
This method is a no-op if the encoder has already been flushed.
| out | the given output buffer. |
|---|
CoderResult.UNDERFLOW or
CoderResult.OVERFLOW or
CoderResult.MALFORMED| IllegalStateException | if this encoder isn't already flushed or at end of input. |
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Tests whether the given argument is legal as this encoder's replacement byte array. The given byte array is legal if and only if it can be decoded into characters.
Returns this encoder's CodingErrorAction when a malformed
input error occurred during the encoding process.
Returns the maximum number of bytes which can be created by this encoder for one input character, must be positive.
Sets this encoder's action on malformed input error.
This method will call the
implOnMalformedInput
method with the given new action as argument.
| newAction | the new action on malformed input error. |
|---|
| IllegalArgumentException | if the given newAction is null. |
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Sets this encoder's action on unmappable character error.
This method will call the
implOnUnmappableCharacter
method with the given new action as argument.
| newAction | the new action on unmappable character error. |
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| IllegalArgumentException | if the given newAction is null. |
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Sets the new replacement value.
This method first checks the given replacement's validity, then changes
the replacement value and finally calls the
implReplaceWith method with the given
new replacement as argument.
| replacement | the replacement byte array, cannot be null or empty, its
length cannot be larger than maxBytesPerChar,
and it must be legal replacement, which can be justified by
calling isLegalReplacement(byte[] replacement). |
|---|
| IllegalArgumentException | if the given replacement cannot satisfy the requirement mentioned above. |
|---|
Returns the replacement byte array, which is never null or empty.
Resets this encoder. This method will reset the internal state and then
calls implReset() to reset any state related to the
specific charset.
Returns this encoder's CodingErrorAction when unmappable
character occurred during encoding process.
Encodes characters into bytes. This method is called by
encode.
This method will implement the essential encoding operation, and it won't
stop encoding until either all the input characters are read, the output
buffer is filled, or some exception is encountered. Then it will
return a CoderResult object indicating the result of the
current encoding operation. The rule to construct the
CoderResult is the same as for
encode. When an
exception is encountered in the encoding operation, most implementations
of this method will return a relevant result object to the
encode method, and
subclasses may handle the exception and
implement the error action themselves.
The buffers are scanned from their current positions, and their positions
will be modified accordingly, while their marks and limits will be
intact. At most in.remaining() characters
will be read, and out.remaining() bytes
will be written.
Note that some implementations may pre-scan the input buffer and return
CoderResult.UNDERFLOW until it receives sufficient input.
| in | the input buffer. |
|---|---|
| out | the output buffer. |
CoderResult instance indicating the result.
Flushes this encoder. The default implementation does nothing and always
returns CoderResult.UNDERFLOW; this method can be
overridden if needed.
| out | the output buffer. |
|---|
CoderResult.UNDERFLOW or
CoderResult.OVERFLOW.
Notifies that this encoder's CodingErrorAction specified
for malformed input error has been changed. The default implementation
does nothing; this method can be overridden if needed.
| newAction | the new action. |
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Notifies that this encoder's CodingErrorAction specified
for unmappable character error has been changed. The default
implementation does nothing; this method can be overridden if needed.
| newAction | the new action. |
|---|
Notifies that this encoder's replacement has been changed. The default implementation does nothing; this method can be overridden if needed.
| newReplacement | the new replacement string. |
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Resets this encoder's charset related state. The default implementation does nothing; this method can be overridden if needed.