Class HandlerBase

  • All Implemented Interfaces:
    XmlHandler
    Direct Known Subclasses:
    DocManager, MoMLParser, MultipageParser, PlotBoxMLParser, PtalonMLHandler

    public class HandlerBase
    extends java.lang.Object
    implements XmlHandler
    Convenience base class for AElfred handlers.

    This base class implements the XmlHandler interface with (mostly empty) default handlers. You are not required to use this, but if you need to handle only a few events, you might find it convenient to extend this class rather than implementing the entire interface. This example overrides only the charData method, using the defaults for the others:

     import com.microstar.xml.HandlerBase;
    
     public class MyHandler extends HandlerBase {
       public void charData (char ch[], int start, int length)
       {
         System.out.println("Data: " + new String (ch, start, length));
       }
     }
     

    This class is optional, but if you use it, you must also include the XmlException class.

    Do not extend this if you are using SAX; extend org.xml.sax.HandlerBase instead.

    Since:
    Ptolemy II 0.2
    Version:
    1.1
    Author:
    Copyright (c) 1998 by Microstar Software Ltd., written by David Megginson <dmeggins@microstar.com>
    See Also:
    XmlHandler, XmlException
    • Constructor Summary

      Constructors 
      Constructor Description
      HandlerBase()  
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void attribute​(java.lang.String aname, java.lang.String value, boolean isSpecified)
      Handle an attribute assignment.
      void charData​(char[] ch, int start, int length)
      Handle character data.
      void doctypeDecl​(java.lang.String name, java.lang.String publicId, java.lang.String systemId)
      Handle a document type declaration.
      void endDocument()
      Handle the end of the document.
      void endElement​(java.lang.String elname)
      Handle the end of an element.
      void endExternalEntity​(java.lang.String systemId)
      Handle the end of an external entity.
      void error​(java.lang.String message, java.lang.String systemId, int line, int column)
      Throw an exception for a fatal error.
      void ignorableWhitespace​(char[] ch, int start, int length)
      Handle ignorable whitespace.
      void processingInstruction​(java.lang.String target, java.lang.String data)
      Handle a processing instruction.
      java.lang.Object resolveEntity​(java.lang.String publicId, java.lang.String systemId)
      Resolve an external entity.
      void startDocument()
      Handle the start of the document.
      void startElement​(java.lang.String elname)
      Handle the start of an element.
      void startExternalEntity​(java.lang.String systemId)
      Handle the start of an external entity.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • HandlerBase

        public HandlerBase()
    • Method Detail

      • startDocument

        public void startDocument()
                           throws java.lang.Exception
        Handle the start of the document.

        The default implementation does nothing.

        Specified by:
        startDocument in interface XmlHandler
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.startDocument()
      • endDocument

        public void endDocument()
                         throws java.lang.Exception
        Handle the end of the document.

        The default implementation does nothing.

        Specified by:
        endDocument in interface XmlHandler
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.endDocument()
      • resolveEntity

        public java.lang.Object resolveEntity​(java.lang.String publicId,
                                              java.lang.String systemId)
                                       throws java.lang.Exception
        Resolve an external entity.

        The default implementation simply returns the supplied system identifier.

        Specified by:
        resolveEntity in interface XmlHandler
        Parameters:
        publicId - The public identifier, or null if none was supplied.
        systemId - The system identifier.
        Returns:
        The replacement system identifier, or null to use the default.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.resolveEntity(java.lang.String, java.lang.String)
      • startExternalEntity

        public void startExternalEntity​(java.lang.String systemId)
                                 throws java.lang.Exception
        Handle the start of an external entity.

        The default implementation does nothing.

        Specified by:
        startExternalEntity in interface XmlHandler
        Parameters:
        systemId - The URI of the external entity that is starting.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.startExternalEntity(java.lang.String)
      • endExternalEntity

        public void endExternalEntity​(java.lang.String systemId)
                               throws java.lang.Exception
        Handle the end of an external entity.

        The default implementation does nothing.

        Specified by:
        endExternalEntity in interface XmlHandler
        Parameters:
        systemId - The URI of the external entity that is ending.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.endExternalEntity(java.lang.String)
      • doctypeDecl

        public void doctypeDecl​(java.lang.String name,
                                java.lang.String publicId,
                                java.lang.String systemId)
                         throws java.lang.Exception
        Handle a document type declaration.

        The default implementation does nothing.

        Specified by:
        doctypeDecl in interface XmlHandler
        Parameters:
        name - The document type name.
        publicId - The public identifier, or null if unspecified.
        systemId - The system identifier, or null if unspecified.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.doctypeDecl(java.lang.String, java.lang.String, java.lang.String)
      • attribute

        public void attribute​(java.lang.String aname,
                              java.lang.String value,
                              boolean isSpecified)
                       throws java.lang.Exception
        Handle an attribute assignment.

        The default implementation does nothing.

        Specified by:
        attribute in interface XmlHandler
        Parameters:
        aname - The name of the attribute.
        value - The value of the attribute, or null if the attribute is #IMPLIED.
        isSpecified - True if the value was specified, false if it was defaulted from the DTD.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.attribute(java.lang.String, java.lang.String, boolean)
      • startElement

        public void startElement​(java.lang.String elname)
                          throws java.lang.Exception
        Handle the start of an element.

        The default implementation does nothing.

        Specified by:
        startElement in interface XmlHandler
        Parameters:
        elname - The element type name.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.startElement(java.lang.String)
      • endElement

        public void endElement​(java.lang.String elname)
                        throws java.lang.Exception
        Handle the end of an element.

        The default implementation does nothing.

        Specified by:
        endElement in interface XmlHandler
        Parameters:
        elname - The element type name.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.endElement(java.lang.String)
      • charData

        public void charData​(char[] ch,
                             int start,
                             int length)
                      throws java.lang.Exception
        Handle character data.

        The default implementation does nothing.

        Specified by:
        charData in interface XmlHandler
        Parameters:
        ch - The character data.
        start - The starting position in the array.
        length - The number of characters available.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.charData(char[], int, int)
      • ignorableWhitespace

        public void ignorableWhitespace​(char[] ch,
                                        int start,
                                        int length)
                                 throws java.lang.Exception
        Handle ignorable whitespace.

        The default implementation does nothing.

        Specified by:
        ignorableWhitespace in interface XmlHandler
        Parameters:
        ch - The literal whitespace characters.
        start - The starting position in the array.
        length - The number of whitespace characters available.
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.ignorableWhitespace(char[], int, int)
      • processingInstruction

        public void processingInstruction​(java.lang.String target,
                                          java.lang.String data)
                                   throws java.lang.Exception
        Handle a processing instruction.

        The default implementation does nothing.

        Specified by:
        processingInstruction in interface XmlHandler
        Parameters:
        target - The target (the name at the start of the PI).
        data - The data, if any (the rest of the PI).
        Throws:
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.processingInstruction(java.lang.String, java.lang.String)
      • error

        public void error​(java.lang.String message,
                          java.lang.String systemId,
                          int line,
                          int column)
                   throws XmlException,
                          java.lang.Exception
        Throw an exception for a fatal error.

        The default implementation throws XmlException.

        Specified by:
        error in interface XmlHandler
        Parameters:
        message - The error message.
        systemId - The system identifier of the entity that contains the error.
        line - The approximate line number of the error.
        column - The approximate column number of the error.
        Throws:
        XmlException - A specific parsing error.
        java.lang.Exception - Derived methods may throw exceptions.
        See Also:
        XmlHandler.error(java.lang.String, java.lang.String, int, int)