public class

HTMLDocument

extends DefaultStyledDocument
java.lang.Object
   ↳ javax.swing.text.AbstractDocument
     ↳ javax.swing.text.DefaultStyledDocument
       ↳ javax.swing.text.html.HTMLDocument

Class Overview

A document that models HTML. The purpose of this model is to support both browsing and editing. As a result, the structure described by an HTML document is not exactly replicated by default. The element structure that is modeled by default, is built by the class HTMLDocument.HTMLReader, which implements the HTMLEditorKit.ParserCallback protocol that the parser expects. To change the structure one can subclass HTMLReader, and reimplement the method getReader(int) to return the new reader implementation. The documentation for HTMLReader should be consulted for the details of the default structure created. The intent is that the document be non-lossy (although reproducing the HTML format may result in a different format).

The document models only HTML, and makes no attempt to store view attributes in it. The elements are identified by the StyleContext.NameAttribute attribute, which should always have a value of type HTML.Tag that identifies the kind of element. Some of the elements (such as comments) are synthesized. The HTMLFactory uses this attribute to determine what kind of view to build.

This document supports incremental loading. The TokenThreshold property controls how much of the parse is buffered before trying to update the element structure of the document. This property is set by the EditorKit so that subclasses can disable it.

The Base property determines the URL against which relative URLs are resolved. By default, this will be the Document.StreamDescriptionProperty if the value of the property is a URL. If a <BASE> tag is encountered, the base will become the URL specified by that tag. Because the base URL is a property, it can of course be set directly.

The default content storage mechanism for this document is a gap buffer (GapContent). Alternatives can be supplied by using the constructor that takes a Content implementation.

Modifying HTMLDocument

In addition to the methods provided by Document and StyledDocument for mutating an HTMLDocument, HTMLDocument provides a number of convenience methods. The following methods can be used to insert HTML content into an existing document.

The following examples illustrate using these methods. Each example assumes the HTML document is initialized in the following way:

 JEditorPane p = new JEditorPane();
 p.setContentType("text/html");
 p.setText("..."); // Document text is provided below.
 HTMLDocument d = (HTMLDocument) p.getDocument();

With the following HTML content:

 <html>
   <head>
     <title>An example HTMLDocument</title>
     <style type="text/css">
       div { background-color: silver; }
       ul { color: red; }
     </style>
   </head>
   <body>
     <div id="BOX">
       <p>Paragraph 1</p>
       <p>Paragraph 2</p>
     </div>
   </body>
 </html>

All the methods for modifying an HTML document require an Element. Elements can be obtained from an HTML document by using the method getElement(Element, Object, Object). It returns the first descendant element that contains the specified attribute with the given value, in depth-first order. For example, d.getElement(d.getDefaultRootElement(), StyleConstants.NameAttribute, HTML.Tag.P) returns the first paragraph element.

A convenient shortcut for locating elements is the method getElement(String); returns an element whose ID attribute matches the specified value. For example, d.getElement("BOX") returns the DIV element.

The getIterator(HTML.Tag) method can also be used for finding all occurrences of the specified HTML tag in the document.

Inserting elements

Elements can be inserted before or after the existing children of any non-leaf element by using the methods insertAfterStart and insertBeforeEnd. For example, if e is the DIV element, d.insertAfterStart(e, "<ul><li>List Item</li></ul>") inserts the list before the first paragraph, and d.insertBeforeEnd(e, "<ul><li>List Item</li></ul>") inserts the list after the last paragraph. The DIV block becomes the parent of the newly inserted elements.

Sibling elements can be inserted before or after any element by using the methods insertBeforeStart and insertAfterEnd. For example, if e is the DIV element, d.insertBeforeStart(e, "<ul><li>List Item</li></ul>") inserts the list before the DIV element, and d.insertAfterEnd(e, "<ul><li>List Item</li></ul>") inserts the list after the DIV element. The newly inserted elements become siblings of the DIV element.

Replacing elements

Elements and all their descendants can be replaced by using the methods setInnerHTML and setOuterHTML. For example, if e is the DIV element, d.setInnerHTML(e, "<ul><li>List Item</li></ul>") replaces all children paragraphs with the list, and d.setOuterHTML(e, "<ul><li>List Item</li></ul>") replaces the DIV element itself. In latter case the parent of the list is the BODY element.

Summary

The following table shows the example document and the results of various methods described above.

Example insertAfterStart insertBeforeEnd insertBeforeStart insertAfterEnd setInnerHTML setOuterHTML

Paragraph 1

Paragraph 2
  • List Item

Paragraph 1

Paragraph 2

Paragraph 1

Paragraph 2

  • List Item
  • List Item

Paragraph 1

Paragraph 2

Paragraph 1

Paragraph 2

  • List Item
  • List Item
  • List Item

Warning: Serialized objects of this class will not be compatible with future Swing releases. The current serialization support is appropriate for short term storage or RMI between applications running the same version of Swing. As of 1.4, support for long term storage of all JavaBeansTM has been added to the java.beans package. Please see XMLEncoder.

Summary

Nested Classes
class HTMLDocument.BlockElement An element that represents a structural block of HTML. 
class HTMLDocument.HTMLReader An HTML reader to load an HTML document with an HTML element structure. 
class HTMLDocument.Iterator An iterator to iterate over a particular type of tag. 
class HTMLDocument.RunElement An element that represents a chunk of text that has a set of HTML character level attributes assigned to it. 
Constants
String AdditionalComments Document property key value.
[Expand]
Inherited Constants
From class javax.swing.text.DefaultStyledDocument
From class javax.swing.text.AbstractDocument
From interface javax.swing.text.Document
[Expand]
Inherited Fields
From class javax.swing.text.DefaultStyledDocument
From class javax.swing.text.AbstractDocument
Public Constructors
HTMLDocument()
Constructs an HTML document using the default buffer size and a default StyleSheet.
HTMLDocument(StyleSheet styles)
Constructs an HTML document with the default content storage implementation and the specified style/attribute storage mechanism.
HTMLDocument(AbstractDocument.Content c, StyleSheet styles)
Constructs an HTML document with the given content storage implementation and the given style/attribute storage mechanism.
Public Methods
URL getBase()
Returns the location to resolve relative URLs against.
Element getElement(String id)
Returns the element that has the given id Attribute.
Element getElement(Element e, Object attribute, Object value)
Returns the child element of e that contains the attribute, attribute with value value, or null if one isn't found.
HTMLDocument.Iterator getIterator(HTML.Tag t)
Fetches an iterator for the specified HTML tag.
HTMLEditorKit.Parser getParser()
Returns the parser that is used when inserting HTML into the existing document.
boolean getPreservesUnknownTags()
Returns the behavior the parser observes when encountering unknown tags.
HTMLEditorKit.ParserCallback getReader(int pos, int popDepth, int pushDepth, HTML.Tag insertTag)
Returns the reader for the parser to use to load the document with HTML.
HTMLEditorKit.ParserCallback getReader(int pos)
Fetches the reader for the parser to use when loading the document with HTML.
StyleSheet getStyleSheet()
Fetches the StyleSheet with the document-specific display rules (CSS) that were specified in the HTML document itself.
int getTokenThreshold()
Gets the number of tokens to buffer before trying to update the documents element structure.
void insertAfterEnd(Element elem, String htmlText)
Inserts the HTML specified as a string after the the end of the given element.
void insertAfterStart(Element elem, String htmlText)
Inserts the HTML specified as a string at the start of the element.
void insertBeforeEnd(Element elem, String htmlText)
Inserts the HTML specified as a string at the end of the element.
void insertBeforeStart(Element elem, String htmlText)
Inserts the HTML specified as a string before the start of the given element.
void processHTMLFrameHyperlinkEvent(HTMLFrameHyperlinkEvent e)
Processes HyperlinkEvents that are generated by documents in an HTML frame.
void setBase(URL u)
Sets the location to resolve relative URLs against.
void setInnerHTML(Element elem, String htmlText)
Replaces the children of the given element with the contents specified as an HTML string.
void setOuterHTML(Element elem, String htmlText)
Replaces the given element in the parent with the contents specified as an HTML string.
void setParagraphAttributes(int offset, int length, AttributeSet s, boolean replace)
Sets attributes for a paragraph.
void setParser(HTMLEditorKit.Parser parser)
Sets the parser that is used by the methods that insert html into the existing document, such as setInnerHTML, and setOuterHTML.
void setPreservesUnknownTags(boolean preservesTags)
Determines how unknown tags are handled by the parser.
void setTokenThreshold(int n)
Sets the number of tokens to buffer before trying to update the documents element structure.
Protected Methods
void create(ElementSpec[] data)
Replaces the contents of the document with the given element specifications.
Element createBranchElement(Element parent, AttributeSet a)
Creates a document branch element, that can contain other elements.
AbstractDocument.AbstractElement createDefaultRoot()
Creates the root element to be used to represent the default document structure.
Element createLeafElement(Element parent, AttributeSet a, int p0, int p1)
Creates a document leaf element that directly represents text (doesn't have any children).
void fireChangedUpdate(DocumentEvent e)
Notifies all listeners that have registered interest for notification on this event type.
void fireUndoableEditUpdate(UndoableEditEvent e)
Notifies all listeners that have registered interest for notification on this event type.
void insert(int offset, ElementSpec[] data)
Inserts new elements in bulk.
void insertUpdate(AbstractDocument.DefaultDocumentEvent chng, AttributeSet attr)
Updates document structure as a result of text insertion.
[Expand]
Inherited Methods
From class javax.swing.text.DefaultStyledDocument
From class javax.swing.text.AbstractDocument
From class java.lang.Object
From interface javax.swing.text.Document
From interface javax.swing.text.StyledDocument

Constants

public static final String AdditionalComments

Document property key value. The value for the key will be a Vector of Strings that are comments not found in the body.

Constant Value: "AdditionalComments"

Public Constructors

public HTMLDocument ()

Constructs an HTML document using the default buffer size and a default StyleSheet. This is a convenience method for the constructor HTMLDocument(Content, StyleSheet).

public HTMLDocument (StyleSheet styles)

Constructs an HTML document with the default content storage implementation and the specified style/attribute storage mechanism. This is a convenience method for the constructor HTMLDocument(Content, StyleSheet).

Parameters
styles the styles

public HTMLDocument (AbstractDocument.Content c, StyleSheet styles)

Constructs an HTML document with the given content storage implementation and the given style/attribute storage mechanism.

Parameters
c the container for the content
styles the styles

Public Methods

public URL getBase ()

Returns the location to resolve relative URLs against. By default this will be the document's URL if the document was loaded from a URL. If a base tag is found and can be parsed, it will be used as the base location.

Returns
  • the base location

public Element getElement (String id)

Returns the element that has the given id Attribute. If the element can't be found, null is returned. Note that this method works on an Attribute, not a character tag. In the following HTML snippet: <a id="HelloThere"> the attribute is 'id' and the character tag is 'a'. This is a convenience method for getElement(RootElement, HTML.Attribute.id, id). This is not thread-safe.

Parameters
id the string representing the desired Attribute
Returns
  • the element with the specified Attribute or null if it can't be found, or null if id is null
See Also

public Element getElement (Element e, Object attribute, Object value)

Returns the child element of e that contains the attribute, attribute with value value, or null if one isn't found. This is not thread-safe.

Parameters
e the root element where the search begins
attribute the desired Attribute
value the values for the specified Attribute
Returns
  • the element with the specified Attribute and the specified value, or null if it can't be found
See Also

public HTMLDocument.Iterator getIterator (HTML.Tag t)

Fetches an iterator for the specified HTML tag. This can be used for things like iterating over the set of anchors contained, or iterating over the input elements.

Parameters
t the requested HTML.Tag
Returns
  • the Iterator for the given HTML tag
See Also

public HTMLEditorKit.Parser getParser ()

Returns the parser that is used when inserting HTML into the existing document.

Returns
  • the parser used for text insertion

public boolean getPreservesUnknownTags ()

Returns the behavior the parser observes when encountering unknown tags.

Returns
  • true if unknown tags are to be preserved when parsing
See Also

public HTMLEditorKit.ParserCallback getReader (int pos, int popDepth, int pushDepth, HTML.Tag insertTag)

Returns the reader for the parser to use to load the document with HTML. This is implemented to return an instance of HTMLDocument.HTMLReader. Subclasses can reimplement this method to change how the document gets structured if desired. (For example, to handle custom tags, or structurally represent character style elements.)

This is a convenience method for getReader(int, int, int, HTML.Tag, TRUE).

Parameters
popDepth the number of ElementSpec.EndTagTypes to generate before inserting
pushDepth the number of ElementSpec.StartTagTypes with a direction of ElementSpec.JoinNextDirection that should be generated before inserting, but after the end tags have been generated
insertTag the first tag to start inserting into document
Returns
  • the reader used by the parser to load the document

public HTMLEditorKit.ParserCallback getReader (int pos)

Fetches the reader for the parser to use when loading the document with HTML. This is implemented to return an instance of HTMLDocument.HTMLReader. Subclasses can reimplement this method to change how the document gets structured if desired. (For example, to handle custom tags, or structurally represent character style elements.)

Parameters
pos the starting position
Returns
  • the reader used by the parser to load the document

public StyleSheet getStyleSheet ()

Fetches the StyleSheet with the document-specific display rules (CSS) that were specified in the HTML document itself.

Returns
  • the StyleSheet

public int getTokenThreshold ()

Gets the number of tokens to buffer before trying to update the documents element structure. The default value is Integer.MAX_VALUE.

Returns
  • the number of tokens to buffer

public void insertAfterEnd (Element elem, String htmlText)

Inserts the HTML specified as a string after the the end of the given element.

Consider the following structure (the elem parameter is in bold).

     <body>
       |
     <div>
      /  \
    <p>   <p>

Invoking insertAfterEnd(elem, "<ul><li>") results in the following structure (new elements are in red).

        <body>
         /  \
      <div> <ul>
       / \    \
     <p> <p>  <li>

Unlike the insertBeforeEnd method, new elements become siblings of the specified element, not children.

If either elem or htmlText parameter is null, no changes are made to the document.

For this to work correcty, the document must have an HTMLEditorKit.Parser set. This will be the case if the document was created from an HTMLEditorKit via the createDefaultDocument method.

Parameters
elem the element the content is inserted after
htmlText the string to be parsed and inserted after elem
Throws
IllegalStateException if an HTMLEditorKit.Parser has not been set on the document
BadLocationException
IOException

public void insertAfterStart (Element elem, String htmlText)

Inserts the HTML specified as a string at the start of the element.

Consider the following structure (the elem parameter is in bold).

     <body>
       |
     <div>
      /  \
    <p>   <p>

Invoking insertAfterStart(elem, "<ul><li>") results in the following structure (new elements are in red).

        <body>
          |
        <div>
       /  |  \
    <ul> <p> <p>
     /
  <li>

Unlike the insertBeforeStart method, new elements become children of the specified element, not siblings.

Parameter elem must not be a leaf element, otherwise an IllegalArgumentException is thrown. If either elem or htmlText parameter is null, no changes are made to the document.

For this to work correcty, the document must have an HTMLEditorKit.Parser set. This will be the case if the document was created from an HTMLEditorKit via the createDefaultDocument method.

Parameters
elem the branch element to be the root for the new text
htmlText the string to be parsed and assigned to elem
Throws
IllegalArgumentException if elem is a leaf
IllegalStateException if an HTMLEditorKit.Parser has not been set on the document
BadLocationException
IOException

public void insertBeforeEnd (Element elem, String htmlText)

Inserts the HTML specified as a string at the end of the element.

If elem's children are leaves, and the character at a elem.getEndOffset() - 1 is a newline, this will insert before the newline so that there isn't text after the newline.

Consider the following structure (the elem parameter is in bold).

     <body>
       |
     <div>
      /  \
    <p>   <p>

Invoking insertBeforeEnd(elem, "<ul><li>") results in the following structure (new elements are in red).

        <body>
          |
        <div>
       /  |  \
     <p> <p> <ul>
               \
               <li>

Unlike the insertAfterEnd method, new elements become children of the specified element, not siblings.

Parameter elem must not be a leaf element, otherwise an IllegalArgumentException is thrown. If either elem or htmlText parameter is null, no changes are made to the document.

For this to work correcty, the document must have an HTMLEditorKit.Parser set. This will be the case if the document was created from an HTMLEditorKit via the createDefaultDocument method.

Parameters
elem the element to be the root for the new text
htmlText the string to be parsed and assigned to elem
Throws
IllegalArgumentException if elem is a leaf
IllegalStateException if an HTMLEditorKit.Parser has not been set on the document
BadLocationException
IOException

public void insertBeforeStart (Element elem, String htmlText)

Inserts the HTML specified as a string before the start of the given element.

Consider the following structure (the elem parameter is in bold).

     <body>
       |
     <div>
      /  \
    <p>   <p>

Invoking insertBeforeStart(elem, "<ul><li>") results in the following structure (new elements are in red).

        <body>
         /  \
      <ul> <div>
       /    /  \
     <li> <p>  <p>

Unlike the insertAfterStart method, new elements become siblings of the specified element, not children.

If either elem or htmlText parameter is null, no changes are made to the document.

For this to work correcty, the document must have an HTMLEditorKit.Parser set. This will be the case if the document was created from an HTMLEditorKit via the createDefaultDocument method.

Parameters
elem the element the content is inserted before
htmlText the string to be parsed and inserted before elem
Throws
IllegalStateException if an HTMLEditorKit.Parser has not been set on the document
BadLocationException
IOException

public void processHTMLFrameHyperlinkEvent (HTMLFrameHyperlinkEvent e)

Processes HyperlinkEvents that are generated by documents in an HTML frame. The HyperlinkEvent type, as the parameter suggests, is HTMLFrameHyperlinkEvent. In addition to the typical information contained in a HyperlinkEvent, this event contains the element that corresponds to the frame in which the click happened (the source element) and the target name. The target name has 4 possible values:

  • _self
  • _parent
  • _top
  • a named frame
If target is _self, the action is to change the value of the HTML.Attribute.SRC attribute and fires a ChangedUpdate event.

If the target is _parent, then it deletes the parent element, which is a <FRAMESET> element, and inserts a new <FRAME> element, and sets its HTML.Attribute.SRC attribute to have a value equal to the destination URL and fire a RemovedUpdate and InsertUpdate.

If the target is _top, this method does nothing. In the implementation of the view for a frame, namely the FrameView, the processing of _top is handled. Given that _top implies replacing the entire document, it made sense to handle this outside of the document that it will replace.

If the target is a named frame, then the element hierarchy is searched for an element with a name equal to the target, its HTML.Attribute.SRC attribute is updated and a ChangedUpdate event is fired.

Parameters
e the event

public void setBase (URL u)

Sets the location to resolve relative URLs against. By default this will be the document's URL if the document was loaded from a URL. If a base tag is found and can be parsed, it will be used as the base location.

This also sets the base of the StyleSheet to be u as well as the base of the document.

Parameters
u the desired base URL

public void setInnerHTML (Element elem, String htmlText)

Replaces the children of the given element with the contents specified as an HTML string.

This will be seen as at least two events, n inserts followed by a remove.

Consider the following structure (the elem parameter is in bold).

     <body>
       |
     <div>
      /  \
    <p>   <p>

Invoking setInnerHTML(elem, "<ul><li>") results in the following structure (new elements are in red).

     <body>
       |
     <div>
         \
         <ul>
           \
           <li>

Parameter elem must not be a leaf element, otherwise an IllegalArgumentException is thrown. If either elem or htmlText parameter is null, no changes are made to the document.

For this to work correcty, the document must have an HTMLEditorKit.Parser set. This will be the case if the document was created from an HTMLEditorKit via the createDefaultDocument method.

Parameters
elem the branch element whose children will be replaced
htmlText the string to be parsed and assigned to elem
Throws
IllegalArgumentException if elem is a leaf
IllegalStateException if an HTMLEditorKit.Parser has not been defined
BadLocationException
IOException

public void setOuterHTML (Element elem, String htmlText)

Replaces the given element in the parent with the contents specified as an HTML string.

This will be seen as at least two events, n inserts followed by a remove.

When replacing a leaf this will attempt to make sure there is a newline present if one is needed. This may result in an additional element being inserted. Consider, if you were to replace a character element that contained a newline with <img> this would create two elements, one for the image, ane one for the newline.

If you try to replace the element at length you will most likely end up with two elements, eg setOuterHTML(getCharacterElement (getLength()), "blah") will result in two leaf elements at the end, one representing 'blah', and the other representing the end element.

Consider the following structure (the elem parameter is in bold).

     <body>
       |
     <div>
      /  \
    <p>   <p>

Invoking setOuterHTML(elem, "<ul><li>") results in the following structure (new elements are in red).

    <body>
      |
     <ul>
       \
       <li>

If either elem or htmlText parameter is null, no changes are made to the document.

For this to work correcty, the document must have an HTMLEditorKit.Parser set. This will be the case if the document was created from an HTMLEditorKit via the createDefaultDocument method.

Parameters
elem the element to replace
htmlText the string to be parsed and inserted in place of elem
Throws
IllegalStateException if an HTMLEditorKit.Parser has not been set
BadLocationException
IOException

public void setParagraphAttributes (int offset, int length, AttributeSet s, boolean replace)

Sets attributes for a paragraph.

This method is thread safe, although most Swing methods are not. Please see How to Use Threads for more information.

Parameters
offset the offset into the paragraph (must be at least 0)
length the number of characters affected (must be at least 0)
s the attributes
replace whether to replace existing attributes, or merge them

public void setParser (HTMLEditorKit.Parser parser)

Sets the parser that is used by the methods that insert html into the existing document, such as setInnerHTML, and setOuterHTML.

HTMLEditorKit.createDefaultDocument will set the parser for you. If you create an HTMLDocument by hand, be sure and set the parser accordingly.

Parameters
parser the parser to be used for text insertion

public void setPreservesUnknownTags (boolean preservesTags)

Determines how unknown tags are handled by the parser. If set to true, unknown tags are put in the model, otherwise they are dropped.

Parameters
preservesTags true if unknown tags should be saved in the model, otherwise tags are dropped
See Also

public void setTokenThreshold (int n)

Sets the number of tokens to buffer before trying to update the documents element structure.

Parameters
n the number of tokens to buffer

Protected Methods

protected void create (ElementSpec[] data)

Replaces the contents of the document with the given element specifications. This is called before insert if the loading is done in bursts. This is the only method called if loading the document entirely in one burst.

Parameters
data the new contents of the document

protected Element createBranchElement (Element parent, AttributeSet a)

Creates a document branch element, that can contain other elements. This is implemented to return an element of type HTMLDocument.BlockElement.

Parameters
parent the parent element
a the attributes
Returns
  • the element

protected AbstractDocument.AbstractElement createDefaultRoot ()

Creates the root element to be used to represent the default document structure.

Returns
  • the element base

protected Element createLeafElement (Element parent, AttributeSet a, int p0, int p1)

Creates a document leaf element that directly represents text (doesn't have any children). This is implemented to return an element of type HTMLDocument.RunElement.

Parameters
parent the parent element
a the attributes for the element
p0 the beginning of the range (must be at least 0)
p1 the end of the range (must be at least p0)
Returns
  • the new element

protected void fireChangedUpdate (DocumentEvent e)

Notifies all listeners that have registered interest for notification on this event type. The event instance is lazily created using the parameters passed into the fire method.

Parameters
e the event
See Also

protected void fireUndoableEditUpdate (UndoableEditEvent e)

Notifies all listeners that have registered interest for notification on this event type. The event instance is lazily created using the parameters passed into the fire method.

Parameters
e the event
See Also

protected void insert (int offset, ElementSpec[] data)

Inserts new elements in bulk. This is how elements get created in the document. The parsing determines what structure is needed and creates the specification as a set of tokens that describe the edit while leaving the document free of a write-lock. This method can then be called in bursts by the reader to acquire a write-lock for a shorter duration (i.e. while the document is actually being altered).

Parameters
offset the starting offset
data the element data
Throws
BadLocationException if the given position does not represent a valid location in the associated document.

protected void insertUpdate (AbstractDocument.DefaultDocumentEvent chng, AttributeSet attr)

Updates document structure as a result of text insertion. This will happen within a write lock. This implementation simply parses the inserted content for line breaks and builds up a set of instructions for the element buffer.

Parameters
chng a description of the document change
attr the attributes