XML Step by Step- P17 ppt

Displaying XML Documents Using Data Binding Data binding is the first technique that you’ll learn for displaying an XML document from within a conventional HTML page.. Displaying XML fro

Trang 1

292 XML Step by Step

■ The first and last verses in each stanza are placed in special elements named FIRSTVERSE and LASTVERSE This allows you to format these verses differently than the other verses (The first verse will have a larger first letter and the last verse will be right justified rather than left.)

2 Use your text editor’s Save command to save the document on your hard disk, assigning it the filename Raven04.xml

Raven04.xml

<?xml version=”1.0"?>

<! File Name: Raven04.xml >

<?xml-stylesheet type=”text/css” href=”Raven04.css”?>

<POEM>

<TITLE>The Raven</TITLE>

Edgar Allan Poe

<AUTHOR-BIO>

Edgar Allan Poe was an American writer who lived

from 1809 to 1849.

</AUTHOR-BIO>

</AUTHOR>

<FIRSTVERSE>Once upon a midnight dreary, while I

pondered, weak and weary,</FIRSTVERSE>

<VERSE>Over many a quaint and curious volume of

forgotten lore—</VERSE>

<VERSE>While I nodded, nearly napping,

suddenly there came a tapping,</VERSE>

<VERSE>As of some one gently rapping,

rapping at my chamber door.</VERSE>

<VERSE>”’Tis some visitor,” I muttered,

“tapping at my chamber door—</VERSE>

<LASTVERSE>Only this, and nothing more.”</LASTVERSE>

</STANZA>

<FIRSTVERSE>Ah, distinctly I remember it was in the

Trang 2

Chapter 9 Displaying XML Documents Using Advanced Cascading Style Sheets 293

bleak December,</FIRSTVERSE>

<VERSE>And each separate dying ember wrought its

ghost upon the floor.</VERSE>

<VERSE>Eagerly I wished the morrow;—vainly I had

sought to borrow</VERSE>

<VERSE>From my books surcease of sorrow—sorrow

for the lost Lenore—</VERSE>

<VERSE>For the rare and radiant maiden whom the angels

name Lenore—</VERSE>

<LASTVERSE>Nameless here for evermore.</LASTVERSE>

</STANZA>

<FIRSTVERSE>And the silken sad uncertain rustling

of each purple curtain</FIRSTVERSE>

<VERSE>Thrilled me—filled me with fantastic

terrors never felt before;</VERSE>

<VERSE>So that now, to still the beating of my heart,

I stood repeating:</VERSE>

<VERSE>”’Tis some visitor entreating entrance at

my chamber door—</VERSE>

<VERSE>Some late visitor entreating entrance

at my chamber door;</VERSE>

<LASTVERSE>This it is, and nothing more.”</LASTVERSE>

</STANZA>

<FIRSTVERSE>Presently my soul grew stronger;

hesitating then no longer,</FIRSTVERSE>

<VERSE>”Sir,” said I, “or Madam, truly your

forgiveness I implore;</VERSE>

<VERSE>But the fact is I was napping, and so

gently you came rapping,</VERSE>

<VERSE>And so faintly you came tapping,

tapping at my chamber door,</VERSE>

<VERSE>That I scarce was sure I heard you”—here

I opened wide the door;—</VERSE>

<LASTVERSE>Darkness there, and nothing more.</LASTVERSE>

</STANZA>

</POEM>

Listing 9-8

Trang 3

Chapter 9 Displaying XML Documents Using Advanced Cascading Style Sheets 295

AUTHOR

{word-spacing:.25em}

AUTHOR-BIO

{display:none}

DATE

{font-style:italic}

IMAGE

{background-image:url(RavShade.bmp);

background-repeat:no-repeat;

background-position:center;

width:89px;

height:58px;

float:left}

STANZA

{display:block;

margin-bottom:1em;

color:navy;

line-height:1.25em}

VERSE, FIRSTVERSE, LASTVERSE

{display:block}

FIRSTVERSE:first-letter

{font-size:large}

LASTVERSE

{text-align:right}

Listing 9-9

3 Display the document by opening the Raven04.xml file directly in Internet

Explorer:

Trang 4

Displaying XML

Documents Using

Data Binding

Data binding is the first technique that you’ll learn for displaying an XML

document from within a conventional HTML page Displaying XML from

within HTML pages gives you the best of both worlds: the ability to store

data using XML, with its capacity for describing and structuring virtually

any type of information, plus the ability to display and work with that

information using HTML, with its feature-rich elements (such as tables,

hyperlinks, images, frames, forms, buttons, and other controls) and its

dynamic programmability

In data binding, you link an XML document to an HTML page, and then

bind standard HTML elements, such as SPANs or TABLEs, to individual XML elements or attributes The HTML elements then automatically display the

contents of the XML elements or attributes to which they’re bound

Data binding and the related techniques you’ll learn in this chapter work

best with an XML document that is structured symmetrically, like a typical

database—namely, a document whose elements can be interpreted as a set of

records and fields In its simplest form, such a document consists of a root

element containing a series of elements of the same type (the records), each of which has the same set of child elements that all contain character data (the

fields) An example is the Inventory.xml document you’ll see in Listing 10-1,

in which the BOOK elements can be interpreted as records, and the elements

nested within each BOOK element (TITLE, AUTHOR, and so on) can be inter-preted as fields Later in the chapter, you’ll learn more about the specific docu-ment structures that are suitable for data binding For docudocu-ments that aren’t

suitable, you can use the scripting techniques you’ll explore in Chapter 11

CHAPTER

10

Trang 5

In this chapter, you’ll first gain an overview of the two main steps for data bind-ing You’ll then learn in detail how to link the XML document to the HTML page (the first main step), and how to bind HTML elements to XML elements and attributes (the second main step) Finally, you’ll learn how to program a Web page using scripts that employ the same underlying programming object as data binding (namely, the Data Source Object, or DSO) You can use these scripts in conjunction with data binding—or independently of it

In Chapter 11, you’ll learn an entirely different way to access, manage, and dis-play an XML document from within an HTML page The techniques given there will let you traverse the entire logical structure of an XML document, and you can use them with any type of XML document

tip

For more information on using data binding and the DSO with Microsoft Internet Explorer, see the topics “Binding the XML Data Source Object to Data,”

“Using the C++ XML Data Source Object,” and “Using the Master/Detail Feature with the C++ XML Data Source Object” in the Microsoft XML SDK 4.0 help file, or the same topics in the XML SDK documentation provided

by the MSDN (Microsoft Developer Network) Library on the Web at

http://msdn.microsoft.com/library/

The Main Steps

There are two main steps for using data binding:

1 Linking the XML document to the HTML page in which you want to

display the XML data This step is normally done by including an HTML

ment named XML within the HTML page For example, the following ele-ment in an HTML page links the XML docuele-ment Inventory.xml to the page:

2 Binding HTML elements to XML elements or attributes When you bind an

HTML element to an XML element or attribute, the HTML element auto-matically displays the content of the XML element or the value of the XML attribute For instance, the following SPAN element in an HTML page is bound to the AUTHOR element in the linked XML document:

As a result, the SPAN HTML element displays the contents of the AUTHOR XML element

Trang 6

Chapter 10 Displaying XML Documents Using Data Binding 299

The basic technique of data binding really is as simple as this, although you’ll learn many variations in the way you can use it The following sections cover these two steps in detail

The First Step: Linking the XML Document

to the HTML Page

To display an XML document in an HTML page, you must link the document

to the page The easiest way to do this with Microsoft Internet Explorer is to in-clude in the page an HTML element named XML, which is also known as a

data island You can use one of two different forms for a data island.

The first form of data island includes the entire text of the XML document be-tween the XML start-tag and end-tag The data island in the following HTML page is an example:

<HTML>

<HEAD>

<TITLE>Book Inventory</TITLE>

</HEAD>

<BODY>

<?xml version="1.0"?>

<BOOK>

<TITLE>The Adventures of Huckleberry Finn</TITLE>

<AUTHOR>Mark Twain</AUTHOR>

<BINDING>mass market paperback</BINDING>

</BOOK>

<BOOK>

<TITLE>Leaves of Grass</TITLE>

<AUTHOR>Walt Whitman</AUTHOR>

<BINDING>hardcover</BINDING>

</BOOK>

<BOOK>

<TITLE>The Legend of Sleepy Hollow</TITLE>

<AUTHOR>Washington Irving</AUTHOR>

Trang 7

<! File Name: Inventory.xml >

<BOOK>

</BOOK>

<BOOK>

</BOOK>

<BOOK>

</BOOK>

<! other BOOK elements >

</INVENTORY>

The second form of data island conforms more closely to the basic XML tenet

of keeping the data itself (the XML document) separate from the formatting

and processing information (the style sheet, or in this chapter, the HTML page) In particular, the second form makes it easier to maintain the XML document, espe-cially when a single document is displayed in several different HTML pages There-fore, you’ll see only the second form of data island in the examples in this book You should assign to the data island’s ID attribute a unique identifier, which you’ll use to access the XML document from within the HTML page (In the

previous example, I assigned ID the value dsoInventory.)

Trang 8

In the second form of data island, you assign to the SRC attribute the URL of the file containing the XML data You can use a fully qualified URL, as in this example:

<XML

ID=”dsoInventory”

SRC=”http://www.mjyOnline.com/documents/Inventory.xml”>

</XML>

More commonly, however, you use a partial URL that specifies a location rela-tive to the location of the HTML page containing the data island For example, the SRC attribute in the following data island indicates that Inventory.xml is in the same folder as the HTML page:

Relative URLs are more common because the XML document is typically con-tained in the same folder as the HTML page, or perhaps in one of its subfolders

How the XML Data Is Stored

When Internet Explorer opens the HTML page, its XML processor reads and parses the XML document Internet Explorer also creates a programming object

known as a Data Source Object (DSO), which stores, or caches, the XML data

and provides access to this data The DSO stores the XML data as a record set—that is, as a collection of records and their fields For example, if you were

to include the Inventory.xml document (shown in Listing 10-1) in a page as a data island, the DSO would store each BOOK element as a record, and each of the child elements within BOOK (TITLE, AUTHOR, and so on) as a field When you bind an HTML element to an XML element, the DSO automatically supplies the value of the XML element and handles all the details The DSO also lets you directly access and manipulate the stored record set through a collection

of methods, properties, and events Methods are functions that you can call

from the page to access or modify the record set (For example, you can use

methods to move through the records.) Properties are current feature settings

that you can read and sometimes modify from the page (For example, you can

read a property that tells you if you’ve reached the last record.) And events are

occurrences (such as a record value changing) that you can handle from a script function that you include in the page

In the page, the identifier that you assigned to the ID attribute in the data island represents the DSO (In the example in the previous section, this identifier is

dsoInventory.)

Trang 9

ment that contains a hierarchical record set (a more complex record structure that I’ll describe later in the chapter) The following sections explain both ap-proaches to displaying record sets

Using a Single HTML Table to Display a Simple Record Set

You can use a single HTML TABLE element to display an XML document in which the data is organized as a simple record set—that is, an XML document organized as follows:

■ The root element contains a series of record elements, all of the same

type (In this chapter, I sometimes call record elements simply

records.)

■ Each record element contains the same set of field elements, and in

this set a given element type occurs only once (In this chapter, I

sometimes call field elements simply fields.)

■ Each field element contains character data only

note

If a record element contains more than one child element of the same type, or

if a child element contains nested elements, the DSO interprets the child ele-ment as a nested record or record set, not as a field You’ll learn how to dis-play nested records in “Using a Nested Table to Disdis-play a Hierarchical Record Set” later in the chapter

An example of this type of XML document is Inventory.xml, which you’ve seen

in previous chapters It is given again in Listing 10-1 for convenient reference (You’ll find a copy of this file on the companion CD.) In this document, the root element (INVENTORY) contains a set of eight record elements (BOOK ele-ments), and each record element has the same set of field elements, which con-tain only character data (TITLE, AUTHOR, BINDING, PAGES, and PRICE)

Inventory.xml

<! File Name: Inventory.xml >

<BOOK>

Trang 10

</BOOK>

<BOOK>

</BOOK>

<BOOK>

</BOOK>

<BOOK>

<TITLE>The Marble Faun</TITLE>

<AUTHOR>Nathaniel Hawthorne</AUTHOR>

<BINDING>trade paperback</BINDING>

</BOOK>

<BOOK>

<AUTHOR>Herman Melville</AUTHOR>

</BOOK>

<BOOK>

<TITLE>The Portrait of a Lady</TITLE>

<AUTHOR>Henry James</AUTHOR>

</BOOK>

<BOOK>

Định dạng
Số trang	15
Dung lượng	305,61 KB