MACROMEDIA Director MX, Руководство пользователя

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Chapter 22 544
Using XML parser objects
The XML Parser Xtra lets Director developers access the nodes of an XML document. A node can
be a tag (similar to an HTML tag, also called an element), character data (text that does not
appear inside the angle brackets of a tag), or a processing instruction (a special type of tag that
passes data to the parsing application for special processing). You can extract information from
the XML document by looking at its nodes with Lingo. This access to XML data lets users
incorporate XML documents into their movies and selectively extract data from the documents.
An XML document is well formed if it has a coherent nesting structure and no misplaced angle
brackets. Some XML documents can be associated with a document type declaration (DTD) file
that describes specific rules for the XML tags the document uses. The XML parser of the Xtra
checks that the XML follows the general rules of creating and using XML tags to ensure that the
document is well formed. However, the Xtra does not check the DTD file to ensure that the tags
follow the specific rules for XML document tags, which is described by the DTD. For this reason,
the Xtra is called nonvalidating. The creator of the original XML document must follow the rules
described in the DTD. Your Director movie should also include Lingo that checks for errors in
the use of the XML document’s tags.
To use the XML Parser Xtra, create a parser object by using Lingo to assign a new instance of the
Xtra to a variable. This variable now contains the parser object. Use a global variable if you need
to access the XML data from anywhere in the Director movie.
global gParserObject
gParserObject = new(xtra "xmlparser")
The next step is to parse the XML data using the
parseString()
command. The data can come
from the text of a cast member or a string variable. To parse XML from a URL, use
parseURL()
instead.
ParseString()
and
parseURL()
return either
VOID
, which indicates that the command
is successful, or an error code that indicates a problem with the XML data.
The following Lingo statement sets the variable
errCode
to the return value of the
parseString()
command:
errCode = gParserObject.parseString(member("XMLtext").text)
After the XML Parser Xtra parses the data, the parser object contains all the data from the XML
document.
The XML data can be considered a tree structure because most documents have tags nested
within other tags, with each tag being like a branch of the tree.
The following example shows a short XML document:
<?xml version="1.0"?>
<e1><tagName attr1="val1" attr2="val2"/><e2>element 2</e2><e3>element 3</e3>
</e1>
The following example is the same XML with its tree structure shown more clearly:
<?xml version="1.0"?>
<e1>
<tagName attr1="val1" attr2="val2"/>
<e2>element 2</e2>
<e3>element 3</e3>
</e1>
There are two ways to access a parsed XML document. You can use the
makeList()
command to
convert the document into a nested property list and use Lingo’s list-access commands, or you can
use the special Lingo commands of XML Parser Xtra to access the parsed data directly.