IT. Expert System.

Java Standard Edition (SE)

HTMLDocument


javax.swing.text.html

Class HTMLDocument

  • All Implemented Interfaces:
    Serializable, Document, StyledDocument


    public class HTMLDocument
    extends DefaultStyledDocument
    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 e, Object attribute, Object value). 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 t) 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 JavaBeans™ has been added to the java.beans package. Please see XMLEncoder.

    • Field Detail

      • AdditionalComments

        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.
        See Also:
        Constant Field Values
    • Constructor Detail

      • HTMLDocument

        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).
      • HTMLDocument

        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
      • HTMLDocument

        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
    • Method Detail

      • getReader

        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
      • getReader

        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
      • getBase

        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
      • setBase

        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
      • insert

        protected void insert(int offset,
                              DefaultStyledDocument.ElementSpec[] data)
                       throws BadLocationException
        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).
        Overrides:
        insert in class DefaultStyledDocument
        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.
      • insertUpdate

        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.
        Overrides:
        insertUpdate in class DefaultStyledDocument
        Parameters:
        chng - a description of the document change
        attr - the attributes
      • create

        protected void create(DefaultStyledDocument.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.
        Overrides:
        create in class DefaultStyledDocument
        Parameters:
        data - the new contents of the document
      • setParagraphAttributes

        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 Concurrency in Swing for more information.

        Specified by:
        setParagraphAttributes in interface StyledDocument
        Overrides:
        setParagraphAttributes in class DefaultStyledDocument
        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
      • getStyleSheet

        public StyleSheet getStyleSheet()
        Fetches the StyleSheet with the document-specific display rules (CSS) that were specified in the HTML document itself.
        Returns:
        the StyleSheet
      • getIterator

        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:
        HTML.Tag
      • createLeafElement

        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.
        Overrides:
        createLeafElement in class AbstractDocument
        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
      • createBranchElement

        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.
        Overrides:
        createBranchElement in class AbstractDocument
        Parameters:
        parent - the parent element
        a - the attributes
        Returns:
        the element
      • setTokenThreshold

        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
      • getTokenThreshold

        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
      • setPreservesUnknownTags

        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:
        HTML.Tag
      • getPreservesUnknownTags

        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:
        HTML.Tag
      • processHTMLFrameHyperlinkEvent

        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
      • setParser

        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
        Since:
        1.3
      • getParser

        public HTMLEditorKit.Parser getParser()
        Returns the parser that is used when inserting HTML into the existing document.
        Returns:
        the parser used for text insertion
        Since:
        1.3
      • setInnerHTML

        public void setInnerHTML(Element elem,
                                 String htmlText)
                          throws BadLocationException,
                                 IOException
        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 correctly, 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
        Since:
        1.3
      • setOuterHTML

        public void setOuterHTML(Element elem,
                                 String htmlText)
                          throws BadLocationException,
                                 IOException
        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, and 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 correctly, 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
        Since:
        1.3
      • insertAfterStart

        public void insertAfterStart(Element elem,
                                     String htmlText)
                              throws BadLocationException,
                                     IOException
        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 correctly, 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
        Since:
        1.3
      • insertBeforeEnd

        public void insertBeforeEnd(Element elem,
                                    String htmlText)
                             throws BadLocationException,
                                    IOException
        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 correctly, 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
        Since:
        1.3
      • insertBeforeStart

        public void insertBeforeStart(Element elem,
                                      String htmlText)
                               throws BadLocationException,
                                      IOException
        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 correctly, 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
        Since:
        1.3
      • insertAfterEnd

        public void insertAfterEnd(Element elem,
                                   String htmlText)
                            throws BadLocationException,
                                   IOException
        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 correctly, 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
        Since:
        1.3
      • getElement

        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
        Since:
        1.3
        See Also:
        HTML.Attribute
      • getElement

        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
        Since:
        1.3
        See Also:
        HTML.Attribute
      • fireChangedUpdate

        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.
        Overrides:
        fireChangedUpdate in class AbstractDocument
        Parameters:
        e - the event
        See Also:
        EventListenerList
      • fireUndoableEditUpdate

        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.
        Overrides:
        fireUndoableEditUpdate in class AbstractDocument
        Parameters:
        e - the event
        See Also:
        EventListenerList


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