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java.lang.ObjectOutputDocument
public final class OutputDocument
Represents a modified version of an original Source
document.
An OutputDocument
represents an original source document that
has been modified by substituting segments of it with other text.
Each of these substitutions must be registered in the output document,
which is most commonly done using the various replace
, remove
or insert
methods in this class.
These methods internally register one or more OutputSegment
objects to define each substitution.
After all of the substitutions have been registered, the modified text can be retrieved using the
writeTo(Writer)
or toString()
methods.
The registered output segments may be adjacent and may also overlap. An output segment that is completely enclosed by another output segment is not included in the output.
If unexpected results are being generated from an OutputDocument
, the getDebugInfo()
method provides information on each
registered output segment, which should provide enough information to determine the cause of the problem.
In most cases the problem will be caused by overlapping output segments.
The following example converts all externally referenced style sheets to internal style sheets:
URL sourceUrl=new URL(sourceUrlString); String htmlText=Util.getString(new InputStreamReader(sourceUrl.openStream())); Source source=new Source(htmlText); OutputDocument outputDocument=new OutputDocument(source); StringBuffer sb=new StringBuffer(); List linkStartTags=source.findAllStartTags(Tag.LINK); for (Iterator i=linkStartTags.iterator(); i.hasNext();) { StartTag startTag=(StartTag)i.next(); Attributes attributes=startTag.getAttributes(); String rel=attributes.getValue("rel"); if (!"stylesheet".equalsIgnoreCase(rel)) continue; String href=attributes.getValue("href"); if (href==null) continue; String styleSheetContent; try { styleSheetContent=Util.getString(new InputStreamReader(new URL(sourceUrl,href).openStream())); } catch (Exception ex) { continue; // don't convert if URL is invalid } sb.setLength(0); sb.append("<style"); Attribute typeAttribute=attributes.get("type"); if (typeAttribute!=null) sb.append(' ').append(typeAttribute); sb.append(">\n").append(styleSheetContent).append("\n</style>"); outputDocument.replace(startTag,sb); } String convertedHtmlText=outputDocument.toString();
OutputSegment
Constructor Summary | |
---|---|
OutputDocument(Source source)
Constructs a new output document based on the specified source document. |
Method Summary | |
---|---|
java.lang.String |
getDebugInfo()
Returns a string representation of this object useful for debugging purposes. |
long |
getEstimatedMaximumOutputLength()
Returns the estimated maximum number of characters in the output, or -1 if no estimate is available. |
java.util.List |
getRegisteredOutputSegments()
Returns a list all of the registered OutputSegment objects in this output document. |
java.lang.CharSequence |
getSourceText()
Returns the original source text upon which this output document is based. |
void |
insert(int pos,
java.lang.CharSequence text)
Inserts the specified text at the specified character position in this output document. |
void |
register(OutputSegment outputSegment)
Registers the specified output segment in this output document. |
void |
remove(java.util.Collection segments)
Removes all the segments from this output document represented by the specified source Segment objects. |
void |
remove(Segment segment)
Removes the specified segment from this output document. |
java.util.Map |
replace(Attributes attributes,
boolean convertNamesToLowerCase)
Replaces the specified Attributes segment in this output document with the name/value entries
in the returned Map . |
void |
replace(Attributes attributes,
java.util.Map map)
Replaces the specified attributes segment in this source document with the name/value entries in the specified Map . |
void |
replace(FormControl formControl)
Replaces the specified FormControl in this output document. |
void |
replace(FormFields formFields)
Replaces all the constituent form controls from the specified FormFields in this output document. |
void |
replace(int begin,
int end,
char ch)
Replaces the specified segment of this output document with the specified character. |
void |
replace(int begin,
int end,
java.lang.CharSequence text)
Replaces the specified segment of this output document with the specified text. |
void |
replace(Segment segment,
java.lang.CharSequence text)
Replaces the specified segment in this output document with the specified text. |
void |
replaceWithSpaces(int begin,
int end)
Replaces the specified segment of this output document with a string of spaces of the same length. |
java.lang.String |
toString()
Returns the final content of this output document as a String . |
void |
writeTo(java.io.Writer writer)
Writes the final content of this output document to the specified Writer . |
void |
writeTo(java.io.Writer writer,
int begin,
int end)
Writes the specified portion of the final content of this output document to the specified Writer . |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public OutputDocument(Source source)
source
- the source document.Method Detail |
---|
public java.lang.CharSequence getSourceText()
public void remove(Segment segment)
This is equivalent to replace
(segment,null)
.
segment
- the segment to remove.public void remove(java.util.Collection segments)
This is equivalent to the following code:
for (Iterator i=segments.iterator(); i.hasNext();)
remove
((Segment)i.next());
segments
- a collection of segments to remove, represented by source Segment
objects.public void insert(int pos, java.lang.CharSequence text)
pos
- the character position at which to insert the text.text
- the replacement text.public void replace(Segment segment, java.lang.CharSequence text)
Specifying a null
argument to the text
parameter is exactly equivalent to specifying an empty string,
and results in the segment being completely removed from the output document.
segment
- the segment to replace.text
- the replacement text, or null
to remove the segment.public void replace(int begin, int end, java.lang.CharSequence text)
Specifying a null
argument to the text
parameter is exactly equivalent to specifying an empty string,
and results in the segment being completely removed from the output document.
begin
- the character position at which to begin the replacement.end
- the character position at which to end the replacement.text
- the replacement text, or null
to remove the segment.public void replace(int begin, int end, char ch)
begin
- the character position at which to begin the replacement.end
- the character position at which to end the replacement.ch
- the replacement character.public void replace(FormControl formControl)
FormControl
in this output document.
The effect of this method is to register zero or more output segments in the output document as required to reflect previous modifications to the control's state. The state of a control includes its submission value, output style, and whether it has been disabled.
The state of the form control should not be modified after this method is called, as there is no guarantee that subsequent changes either will or will not be reflected in the final output. A second call to this method with the same parameter is not allowed. It is therefore recommended to call this method as the last action before the output is generated.
Although the specifics of the number and nature of the output segments added in any particular circumstance is not defined in the specification, it can generally be assumed that only the minimum changes necessary are made to the original document. If the state of the control has not been modified, calling this method has no effect at all.
formControl
- the form control to replace.replace(FormFields)
public void replace(FormFields formFields)
FormFields
in this output document.
This is equivalent to the following code:
for (Iterator i=formFields.getFormControls()
.iterator(); i.hasNext();)replace
((FormControl)i.next());
The state of any of the form controls in the specified form fields should not be modified after this method is called, as there is no guarantee that subsequent changes either will or will not be reflected in the final output. A second call to this method with the same parameter is not allowed. It is therefore recommended to call this method as the last action before the output is generated.
formFields
- the form fields to replace.replace(FormControl)
public java.util.Map replace(Attributes attributes, boolean convertNamesToLowerCase)
Attributes
segment in this output document with the name/value entries
in the returned Map
.
The returned map initially contains entries representing the attributes from the source document,
which can be modified before output.
The documentation of the replace(Attributes,Map)
method contains more information about the requirements
of the map entries.
Specifying a value of true
as an argument to the convertNamesToLowerCase
parameter
causes all original attribute names to be converted to lower case in the map.
This simplifies the process of finding/updating specific attributes since map keys are case sensitive.
Attribute values are automatically decoded before being loaded into the map.
This method is logically equivalent to:
replace
(attributes, attributes.
populateMap(new LinkedHashMap(),convertNamesToLowerCase)
)
The use of LinkedHashMap
to implement the map ensures (probably unnecessarily) that
existing attributes are output in the same order as they appear in the source document, and new
attributes are output in the same order as they are added.
Source source=new Source(htmlDocument); Attributes bodyAttributes =source.findNextStartTag(0,Tag.BODY).getAttributes(); OutputDocument outputDocument=new OutputDocument(source); Map attributesMap=outputDocument.replace(bodyAttributes,true); attributesMap.put("bgcolor","green"); String htmlDocumentWithGreenBackground=outputDocument.toString();
attributes
- the Attributes
segment defining the span of the segment and initial name/value entries of the returned map.convertNamesToLowerCase
- specifies whether all attribute names are converted to lower case in the map.
Map
containing the name/value entries to be output.replace(Attributes,Map)
public void replace(Attributes attributes, java.util.Map map)
Map
.
This method might be used if the Map
containing the new attribute values
should not be preloaded with the same entries as the source attributes, or a map implementation
other than LinkedHashMap
is required.
Otherwise, the replace(Attributes, boolean convertNamesToLowerCase)
method is generally more useful.
Keys in the map must be String
objects, and values must implement the CharSequence
interface.
An attribute with no value is represented by a map entry with a null
value.
Attribute values are stored unencoded in the map, and are automatically encoded if necessary during output.
The use of invalid characters in attribute names results in unspecified behaviour.
Note that methods in the Attributes
class treat attribute names as case insensitive,
whereas the Map
treats them as case sensitive.
attributes
- the Attributes
object defining the span of the segment to replace.map
- the Map
containing the name/value entries.replace(Attributes, boolean convertNamesToLowerCase)
public void replaceWithSpaces(int begin, int end)
This method is most commonly used to remove segments of the document without affecting the character positions of the remaining elements.
It is used internally to implement the functionality available through the Segment.ignoreWhenParsing()
method.
To remove a segment from the output document completely, use the remove(Segment)
method instead.
begin
- the character position at which to begin the replacement.end
- the character position at which to end the replacement.public void register(OutputSegment outputSegment)
Use this method if you want to use a customised OutputSegment
class.
outputSegment
- the output segment to register.public void writeTo(java.io.Writer writer) throws java.io.IOException
Writer
.
The writeTo(Writer, int begin, int end)
method allows the output of a portion of the output document.
If the output is required in the form of a Reader
, use CharStreamSourceUtil.getReader(this)
instead.
writeTo
in interface CharStreamSource
writer
- the destination java.io.Writer
for the output.
java.io.IOException
- if an I/O exception occurs.toString()
public void writeTo(java.io.Writer writer, int begin, int end) throws java.io.IOException
Writer
.
Any zero-length output segments located at begin
or end
are included in the output.
writer
- the destination java.io.Writer
for the output.begin
- the character position at which to start the output, inclusive.end
- the character position at which to end the output, exclusive.
java.io.IOException
- if an I/O exception occurs.writeTo(Writer)
public long getEstimatedMaximumOutputLength()
CharStreamSource
-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 StringBuffer
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.
getEstimatedMaximumOutputLength
in interface CharStreamSource
-1
if no estimate is available.public java.lang.String toString()
String
.
toString
in interface CharStreamSource
toString
in class java.lang.Object
String
.writeTo(Writer)
public java.lang.String getDebugInfo()
The output includes details of all the registered output segments
.
public java.util.List getRegisteredOutputSegments()
OutputSegment
objects in this output document.
The output segments are sorted in order of their starting position in the document.
The returned list is modifiable and any changes will affect the output generated by this OutputDocument
.
OutputSegment
objects in this output document.
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