XML文件代碼:
<?xml version="1.0"?>
<!DOCTYPE message[
<!ELEMENT message (header,body,(signature|footer))>
<!ELEMENT header (date,from,to+,subject,banner?)>
<!ELEMENT body (paragraph*)>
<!ELEMENT date (date,month,year)>
<!ELEMENT paragraph (#PCDATA)>
<!ATTLIST paragraph size CDATA #REQUIRED>
<!ELEMENT signature (#PCDATA)>
<!ELEMENT footer ANY>
<!ELEMENT day (#PCDATA)>
<!ELEMENT month (#PCDATA)>
<!ATTLIST month type (numberic|character) #REQUIRED>
<!ELEMENT year (#PCDATA)>
<!ATTLIST year format (numeric|character) "numeric" >
<!ELEMENT from (#PCDATA)>
<!ELEMENT to (#PCDATA)>
<!ATTLIST to relationship CDATA #IMPLIED>
<!ELEMENT subject (#PCDATA)>
<!ELEMENT banner (#PCDATA)>
]>
<message >
<header>
<date>
<day>12</day>
<month type="character">MAY</month>
<year>2006</year>
</date>
<from> luliuyan </from>
<to> luliuyan's wife</to>
<to relationship="very close">Your family</to>
<to relationship="not so close">Your friends</to>
<subject> Merry Christmas</subject>
<banner></banner>
</header>
<body>
<paragraph size="1 line">
Best wishes for Christmas
</paragraph>
<paragraph size="2 line">
I love you!!
</paragraph>
</body>
<footer>
<day>Christmas Day</day>
<from>The best for us</from>
</footer>
</message>
<!DOCTYPE message[
<!ELEMENT message (header,body,(signature|footer))>
<!ELEMENT header (date,from,to+,subject,banner?)>
<!ELEMENT body (paragraph*)>
<!ELEMENT date (date,month,year)>
<!ELEMENT paragraph (#PCDATA)>
<!ATTLIST paragraph size CDATA #REQUIRED>
<!ELEMENT signature (#PCDATA)>
<!ELEMENT footer ANY>
<!ELEMENT day (#PCDATA)>
<!ELEMENT month (#PCDATA)>
<!ATTLIST month type (numberic|character) #REQUIRED>
<!ELEMENT year (#PCDATA)>
<!ATTLIST year format (numeric|character) "numeric" >
<!ELEMENT from (#PCDATA)>
<!ELEMENT to (#PCDATA)>
<!ATTLIST to relationship CDATA #IMPLIED>
<!ELEMENT subject (#PCDATA)>
<!ELEMENT banner (#PCDATA)>
]>
<message >
<header>
<date>
<day>12</day>
<month type="character">MAY</month>
<year>2006</year>
</date>
<from> luliuyan </from>
<to> luliuyan's wife</to>
<to relationship="very close">Your family</to>
<to relationship="not so close">Your friends</to>
<subject> Merry Christmas</subject>
<banner></banner>
</header>
<body>
<paragraph size="1 line">
Best wishes for Christmas
</paragraph>
<paragraph size="2 line">
I love you!!
</paragraph>
</body>
<footer>
<day>Christmas Day</day>
<from>The best for us</from>
</footer>
</message>
分析:
看XML文件最重要的是要看它的結構:
從上面的示例我們可以知道，第一層次:message包含三個元素:header,body,signature或者footer(其中一個);
第二層次:
header又包含五個子元素:date,from,to("+"表示to元素出現次數爲一到多次),subject,banner("?"表示banner元素出現次數爲零到多次);
body有子元素paragraph("*"表示paragraph元素可以不出現，或出現一次或多次),而且paragraph有#PCDATA限制，表示不能包含其它元素，且只能是字符數據，另外paragraph含有屬性size, 且size屬性的類型是CDATA，表示是字符數據，#REQUIRED表示使用paragraph元素時必須使用size屬性;
signature元素 也爲字符類型;
footer元素類型爲任意類型ANY;(本例中是包含其它子元素的類型);
第三層次:
date元素又包含day,month(有type屬性),year(有format屬性)三個子元素;
from元素;
to元素有relationship屬性;
如果還有什麼不知道的可以看昨天的關於DTD的理論部分，其實我今天說了好多廢話的，只要把代碼貼出來就行了，大家好好學習了，不要偷懶
