Interface CharStreamSource
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- All Known Subinterfaces:
OutputSegment
- All Known Implementing Classes:
OutputDocument
,Renderer
,SourceCompactor
,SourceFormatter
,TextExtractor
public interface CharStreamSource
Represents a character stream source. The purpose of a class that implements this interface is to output text.For small amounts of data, or when memory usage isn't a prime concern (e.g. in client-side applications), the simplest way to obtain the data is by calling the
toString()
method. If the character stream might contain a large amount of data it is recommended to use thewriteTo(Writer)
method to access the data, especially if running in a multi-user server environment.The advantage of providing textual data via this interface is that it gives the user the choice as to whether they would like to receive the data as a stream of characters, or all as a single string. Furthermore, it allows the "active" stream source (see below) to be easily converted into a "passive" stream source if required.
An active stream source is a stream source that actively outputs to a passive receiver ("sink"). The
writeTo(Writer)
method in this interface signifies an active source as the transmission of the entire data stream takes place when this method is executed. In this case the sink is the object that supplies theWriter
object, and would typically contain agetWriter()
method. The sink is passive because it just supplies aWriter
object to be written to by the code in some other class.A passive stream source is a stream source that is read from by an active sink. For character streams, a passive stream source simply supplies a
Reader
object. The active sink would typically contain areadFrom(Reader)
method which actively reads the entire data stream from theReader
object.The
CharStreamSourceUtil.getReader(CharStreamSource)
method converts aCharStreamSource
into aReader
, allowing the data from the activeCharStreamSource
to be consumed by an active sink with areadFrom(Reader)
method.Every implementing class must override the
toString()
method to return the output as a string.An easy way to implement this is by calling the
CharStreamSourceUtil.toString(this)
method, which buffers the output from thewriteTo(Writer)
method into a string.- See Also:
OutputDocument
,SourceFormatter
,Renderer
,TextExtractor
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
appendTo(java.lang.Appendable appendable)
Appends the output to the specifiedAppendable
object.long
getEstimatedMaximumOutputLength()
Returns the estimated maximum number of characters in the output, or-1
if no estimate is available.java.lang.String
toString()
Returns the output as a string.void
writeTo(java.io.Writer writer)
Writes the output to the specifiedWriter
.
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Method Detail
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writeTo
void writeTo(java.io.Writer writer) throws java.io.IOException
Writes the output to the specifiedWriter
.- Parameters:
writer
- the destinationjava.io.Writer
for the output.- Throws:
java.io.IOException
- if an I/O exception occurs.
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appendTo
void appendTo(java.lang.Appendable appendable) throws java.io.IOException
Appends the output to the specifiedAppendable
object.- Parameters:
appendable
- the destinationjava.lang.Appendable
object for the output.- Throws:
java.io.IOException
- if an I/O exception occurs.
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getEstimatedMaximumOutputLength
long getEstimatedMaximumOutputLength()
Returns the estimated maximum number of characters in the output, or-1
if no estimate is available.The returned value should be used as a guide for efficiency purposes only, for example to set an initial
StringBuilder
capacity. There is no guarantee that the length of the output is indeed less than this value, as classes implementing this method often use assumptions based on typical usage to calculate the estimate.Although implementations of this method should never return a value less than -1, users of this method must not assume that this will always be the case. Standard practice is to interpret any negative value as meaning that no estimate is available.
- Returns:
- the estimated maximum number of characters in the output, or
-1
if no estimate is available.
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toString
java.lang.String toString()
Returns the output as a string.- Overrides:
toString
in classjava.lang.Object
- Returns:
- the output as a string.
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