diva.util.aelfred

Interface XmlHandler

All Known Implementing Classes:

HandlerBase, MSTrainingParser, MultipageParser, SSTrainingParser, XmlReader.Handler, XmlReader.Handler

public interface XmlHandler

XML Processing Interface.

Whenever you parse an XML document, you must provide an object from a class that implements this interface to receive the parsing events.

If you do not want to implement this entire interface, you can extend the HandlerBase convenience class and then implement only what you need.

If you are using SAX, you should implement the SAX handler interfaces rather than this one.

Version:

1.1

Author:

Copyright (c) 1997, 1998 by Microstar Software Ltd., written by David Megginson <dmeggins@microstar.com>

See Also:

XmlParser, HandlerBase, EntityHandler, DocumentHandler, ErrorHandler

Method Summary

Modifier and Type	Method and Description
void	attribute(String aname, String value, boolean isSpecified) Attribute.
void	charData(char[] ch, int start, int length) Character data.
void	doctypeDecl(String name, String publicId, String systemId) Document type declaration.
void	endDocument() End the document.
void	endElement(String elname) End an element.
void	endExternalEntity(String systemId) End an external entity.
void	error(String message, String systemId, int line, int column) Fatal XML parsing error.
void	ignorableWhitespace(char[] ch, int start, int length) Ignorable whitespace.
void	processingInstruction(String target, String data) Processing instruction.
Object	resolveEntity(String publicId, String systemId) Resolve an External Entity.
void	startDocument() Start the document.
void	startElement(String elname) Start an element.
void	startExternalEntity(String systemId) Begin an external entity.

Method Detail

startDocument

void startDocument()
            throws Exception

Start the document.

Ælfred will call this method just before it attempts to read the first entity (the root of the document). It is guaranteed that this will be the first method called.

Throws:

Exception - The handler may throw any exception.

See Also:

endDocument()

endDocument

void endDocument()
          throws Exception

End the document.

Ælfred will call this method once, when it has finished parsing the XML document. It is guaranteed that this will be the last method called.

Throws:

Exception - The handler may throw any exception.

See Also:

startDocument()

resolveEntity

Object resolveEntity(String publicId,
                     String systemId)
              throws Exception

Resolve an External Entity.

Give the handler a chance to redirect external entities to different URIs. Ælfred will call this method for the top-level document entity, for external text (XML) entities, and the external DTD subset (if any).

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:

Exception - The handler may throw any exception.

See Also:

startExternalEntity(java.lang.String), endExternalEntity(java.lang.String)

startExternalEntity

void startExternalEntity(String systemId)
                  throws Exception

Begin an external entity.

Ælfred will call this method at the beginning of each external entity, including the top-level document entity and the external DTD subset (if any).

If necessary, you can use this method to track the location of the current entity so that you can resolve relative URIs correctly.

Parameters:

systemId - The URI of the external entity that is starting.

Throws:

Exception - The handler may throw any exception.

See Also:

endExternalEntity(java.lang.String), resolveEntity(java.lang.String, java.lang.String)

endExternalEntity

void endExternalEntity(String systemId)
                throws Exception

End an external entity.

Ælfred will call this method at the end of each external entity, including the top-level document entity and the external DTD subset.

If necessary, you can use this method to track the location of the current entity so that you can resolve relative URIs correctly.

Parameters:

systemId - The URI of the external entity that is ending.

Throws:

Exception - The handler may throw any exception.

See Also:

startExternalEntity(java.lang.String), resolveEntity(java.lang.String, java.lang.String)

doctypeDecl

void doctypeDecl(String name,
                 String publicId,
                 String systemId)
          throws Exception

Document type declaration.

Ælfred will call this method when or if it encounters the document type (DOCTYPE) declaration.

Please note that the public and system identifiers will not always be a reliable indication of the DTD in use.

Parameters:

name - The document type name.

publicId - The public identifier, or null if unspecified.

systemId - The system identifier, or null if unspecified.

Throws:

Exception - The handler may throw any exception.

attribute

void attribute(String aname,
               String value,
               boolean isSpecified)
        throws Exception

Attribute.

Ælfred will call this method once for each attribute (specified or defaulted) before reporting a startElement event. It is up to your handler to collect the attributes, if necessary.

You may use XmlParser.getAttributeType() to find the attribute's declared type.

Parameters:

name - The name of the attribute.

type - The type of the attribute (see below).

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:

Exception - The handler may throw any exception.

See Also:

startElement(java.lang.String), XmlParser.declaredAttributes(java.lang.String), XmlParser.getAttributeType(java.lang.String, java.lang.String), XmlParser.getAttributeDefaultValue(java.lang.String, java.lang.String)

startElement

void startElement(String elname)
           throws Exception

Start an element.

Ælfred will call this method at the beginning of each element. By the time this is called, all of the attributes for the element will already have been reported using the attribute method.

Parameters:

elname - The element type name.

Throws:

Exception - The handler may throw any exception.

See Also:

attribute(java.lang.String, java.lang.String, boolean), endElement(java.lang.String), XmlParser.declaredElements(), XmlParser.getElementContentType(java.lang.String)

endElement

void endElement(String elname)
         throws Exception

End an element.

Ælfred will call this method at the end of each element (including EMPTY elements).

Parameters:

elname - The element type name.

Throws:

Exception - The handler may throw any exception.

See Also:

startElement(java.lang.String), XmlParser.declaredElements(), XmlParser.getElementContentType(java.lang.String)

charData

void charData(char[] ch,
              int start,
              int length)
       throws Exception

Character data.

Ælfred will call this method once for each chunk of character data found in the contents of elements. Note that the parser may break up a long sequence of characters into smaller chunks and call this method once for each chunk.

Do not attempt to read more than length characters from the array, or to read before the start position.

Parameters:

ch - The character data.

start - The starting position in the array.

length - The number of characters available.

Throws:

Exception - The handler may throw any exception.

ignorableWhitespace

void ignorableWhitespace(char[] ch,
                         int start,
                         int length)
                  throws Exception

Ignorable whitespace.

Ælfred will call this method once for each sequence of ignorable whitespace in element content (never in mixed content).

For details, see section 2.10 of the XML 1.0 recommendation.

Do not attempt to read more than length characters from the array or to read before the start position.

Parameters:

ch - The literal whitespace characters.

start - The starting position in the array.

length - The number of whitespace characters available.

Throws:

Exception - The handler may throw any exception.

processingInstruction

void processingInstruction(String target,
                           String data)
                    throws Exception

Processing instruction.

Ælfred will call this method once for each processing instruction. Note that processing instructions may appear outside of the top-level element. The

Parameters:

target - The target (the name at the start of the PI).

data - The data, if any (the rest of the PI).

Throws:

Exception - The handler may throw any exception.

error

void error(String message,
           String systemId,
           int line,
           int column)
    throws Exception

Fatal XML parsing error.

Ælfred will call this method whenever it encounters a serious error. The parser will attempt to continue past this point so that you can find more possible error points, but if this method is called you should assume that the document is corrupt and you should not try to use its contents.

Note that you can use the XmlException class to encapsulate all of the information provided, though the use of the class is not mandatory.

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:

Exception - The handler may throw any exception.

See Also:

XmlException