jaxpxslt6.html

j2eePDF格式的电子书

<a name="wp65076"> </a><p class="pDefinition">
The <code class="cCode">&lt;xsl:text&gt;</code> function lets you add any text you want, including whitespace. So, it could conceivably be used to output indentation space. The problem is to vary the <span style="font-style: italic">amount</span> of indentation space. XSLT variables seem like a good idea, but they don't work here. The reason is that when you assign a value to a variable in a template, the value is only known <span style="font-style: italic">within</span> that template (statically, at compile time value). Even if the variable is defined globally, the assigned value is not stored in a way that lets it be dynamically known by other templates at runtime. Once <code class="cCode">&lt;apply-templates/&gt;</code> invokes other templates, they are unaware of any variable settings made in other templates. 
</p>
<a name="wp65077"> </a><p class="pDefinitionTerm">
Parameterized templates
</p>
<a name="wp65078"> </a><p class="pDefinition">
Using a &quot;parameterized template&quot; is another way to modify a template's behavior. But determining the amount of indentation space to pass as the parameter remains the crux of the problem! 
</p>
<a name="wp65079"> </a><p class="pBody">
At the moment, then, there does not appear to be any good way to control the indentation of HTML-formatted output. That would be inconvenient if you needed to display or edit the HTML as plain text. But it's not a problem if you do your editing on the XML form, only use the HTML version for display in a browser. (When you view <code class="cCode">stylizer1c.html</code>, for example, you see the results you expect.)
</p>
<a name="wp65081"> </a><h3 class="pHeading2">
Processing the Remaining Structure Elements
</h3>
<a name="wp65082"> </a><p class="pBody">
In this section, you'll process the <code class="cCode">LIST</code> and <code class="cCode">NOTE</code> elements that add additional structure to an article. 
</p>
<hr>
<a name="wp65083"> </a><p class="pNote">
Note: The sample document described in this section is <code class="cCode"><a  href="../examples/jaxp/xslt/samples/article2.xml" target="_blank">article2.xml</a></code>, and the stylesheet used to manipulate it is<code class="cCode"><a  href="../examples/jaxp/xslt/samples/article2.xsl" target="_blank"> article2.xsl</a></code>. The result is <code class="cCode"><a  href="../examples/jaxp/xslt/samples/stylizer2.html" target="_blank">stylizer2.html</a></code>. (The browser-displayable versions are <code class="cCode"><a  href="../examples/jaxp/xslt/samples/article2-xml.html" target="_blank">article2-xml.html</a></code>, <code class="cCode"><a  href="../examples/jaxp/xslt/samples/article2-xsl.html" target="_blank">article2-xsl.html</a></code>, and <code class="cCode"><a  href="../examples/jaxp/xslt/samples/stylizer2-src.html" target="_blank">stylizer2-src.html</a></code>.)
</p>
<hr><a name="wp65084"> </a><p class="pBody">
Start by adding some test data to the sample document:
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
&lt;?xml version=&quot;1.0&quot;?&gt;
&lt;ARTICLE&gt;
&nbsp;&nbsp;&lt;TITLE&gt;A Sample Article&lt;/TITLE&gt;
&nbsp;&nbsp;&lt;SECT&gt;The First Major Section
&nbsp;&nbsp;&nbsp;&nbsp;...
&nbsp;&nbsp;&lt;/SECT&gt;
<code class="cCodeBold">&nbsp;&nbsp;&lt;SECT&gt;The Second Major Section
&nbsp;&nbsp;&nbsp;&nbsp;&lt;PARA&gt;This section adds a LIST and a NOTE.
&nbsp;&nbsp;&nbsp;&nbsp;&lt;PARA&gt;Here is the LIST:
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;LIST type=&quot;ordered&quot;&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;ITEM&gt;Pears&lt;/ITEM&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;ITEM&gt;Grapes&lt;/ITEM&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;/LIST&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/PARA&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;PARA&gt;And here is the NOTE:
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;NOTE&gt;Don&#39;t forget to go to the hardware store 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;on your way to the grocery!
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;/NOTE&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/PARA&gt;
&nbsp;&nbsp;&lt;/SECT&gt; 
</code>&lt;/ARTICLE&gt; <a name="wp65085"> </a>
</pre></div>
<hr>
<a name="wp65086"> </a><p class="pNote">
Note: Although the list and note in the XML file are contained in their respective paragraphs, it really makes no difference whether they are contained or not--the generated HTML will be the same, either way. But having them contained will make them easier to deal with in an outline-oriented editor. 
</p>
<hr><a name="wp65087"> </a><h4 class="pHeading3">
Modify &lt;PARA&gt; handling
</h4>
<a name="wp65088"> </a><p class="pBody">
Next, modify the <code class="cCode">PARA</code> template to account for the fact that we are now allowing some of the structure elements to be embedded with a paragraph:
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
&lt;xsl:template match=&quot;PARA&quot;&gt;
<code class="cCodeStruck">&nbsp;&nbsp;&lt;p&gt;&lt;xsl:apply-templates/&gt;&lt;/p&gt;
</code><code class="cCodeBold">&nbsp;&nbsp;&lt;p&gt; &lt;xsl:apply-templates select=&quot;text()|B|I|U|DEF|LINK&quot;/&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/p&gt;
&nbsp;&nbsp;&lt;xsl:apply-templates select=&quot;PARA|LIST|NOTE&quot;/&gt;
</code>&lt;/xsl:template&gt;<a name="wp65089"> </a>
</pre></div>
<a name="wp65090"> </a><p class="pBody">
This modification uses the same technique you used for section headings. The only difference is that <code class="cCode">SECT</code> elements are not expected within a paragraph. (However, a paragraph could easily exist inside another paragraph, as quoted material, for example.)
</p>
<a name="wp65091"> </a><h4 class="pHeading3">
Process &lt;LIST&gt; and &lt;ITEM&gt; elements
</h4>
<a name="wp65092"> </a><p class="pBody">
Now you're ready to add a template to process <code class="cCode">LIST</code> elements:
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
<code class="cCodeBold">&nbsp;&nbsp;&lt;xsl:template match=&quot;LIST&quot;&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;xsl:if test=&quot;@type=&#39;ordered&#39;&quot;&gt; 
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;ol&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;xsl:apply-templates/&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;/ol&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/xsl:if&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;xsl:if test=&quot;@type=&#39;unordered&#39;&quot;&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;ul&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;xsl:apply-templates/&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;/ul&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/xsl:if&gt;
&nbsp;&nbsp;&lt;/xsl:template&gt;
</code>
&lt;/xsl:stylesheet&gt;<a name="wp65093"> </a>
</pre></div>
<a name="wp65094"> </a><p class="pBody">
The <code class="cCode">&lt;xsl:if&gt;</code> tag uses the <code class="cCode">test=&quot;&quot;</code> attribute to specify a boolean condition. In this case, the value of the <code class="cCode">type</code> attribute is tested, and the list that is generated changes depending on whether the value is <code class="cCode">ordered</code> or <code class="cCode">unordered</code>.
</p>
<a name="wp65095"> </a><p class="pBody">
The two important things to note for this example are:
</p>
<div class="pSmartList1"><ul class="pSmartList1">
<a name="wp65096"> </a><div class="pSmartList1"><li>There is no <code class="cCode">else</code> clause, nor is there a <code class="cCode">return</code> or <code class="cCode">exit</code> statement, so it takes two <code class="cCode">&lt;xsl:if&gt;</code> tags to cover the two options. (Or the <code class="cCode">&lt;xsl:choose&gt;</code> tag could have been used, which provides case-statement functionality.) </li></div>
<a name="wp65097"> </a><div class="pSmartList1"><li>Single quotes are required around the attribute values. Otherwise, the XSLT processor attempts to interpret the word <code class="cCode">ordered</code> as an XPath function, instead of as a string.</li></div>
</ul></div>
<a name="wp65098"> </a><p class="pBody">
Now finish up <code class="cCode">LIST</code> processing by handling <code class="cCode">ITEM</code> elements:
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
<code class="cCodeBold">&nbsp;&nbsp;&lt;xsl:template match=&quot;ITEM&quot;&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;li&gt;&lt;xsl:apply-templates/&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/li&gt;
&nbsp;&nbsp;&lt;/xsl:template&gt;
</code>
&lt;/xsl:stylesheet&gt;<a name="wp65099"> </a>
</pre></div>
<a name="wp65100"> </a><h4 class="pHeading3">
Ordering Templates in a Stylesheet
</h4>
<a name="wp65101"> </a><p class="pBody">
By now, you should have the idea that templates are independent of one another, so it doesn't generally matter where they occur in a file. So from here on, we'll just show the template you need to add. (For the sake of comparison, they're always added at the end of the example stylesheet.) 
</p>
<a name="wp65102"> </a><p class="pBody">
Order <span style="font-style: italic">does</span> make a difference when two templates can apply to the same node. In that case, the one that is defined <span style="font-style: italic">last</span> is the one that is found and processed. For example, to change the ordering of an indented list to use lowercase alphabetics, you could specify a template pattern that looks like this: <code class="cCode">//LIST//LIST</code>. In that template, you would use the HTML option to generate an alphabetic enumeration, instead of a numeric one.
</p>
<a name="wp65103"> </a><p class="pBody">
But such an element could also be identified by the pattern <code class="cCode">//LIST</code>. To make sure the proper processing is done, the template that specifies <code class="cCode">//LIST</code> would have to appear <span style="font-style: italic">before </span>the template the specifies <code class="cCode">//LIST//LIST</code>.
</p>
<a name="wp65104"> </a><h4 class="pHeading3">
Process &lt;NOTE&gt; Elements
</h4>
<a name="wp65105"> </a><p class="pBody">
The last remaining structure element is the <code class="cCode">NOTE</code> element. Add the template shown below to handle that.
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
&nbsp;&nbsp;<code class="cCodeBold">&lt;xsl:template match=&quot;NOTE&quot;&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&lt;blockquote&gt;&lt;b&gt;Note:&lt;/b&gt;&lt;br/&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;xsl:apply-templates/&gt;
&nbsp;&nbsp;&nbsp;&nbsp;&lt;/p&gt;&lt;/blockquote&gt;
&nbsp;&nbsp;&lt;/xsl:template&gt;
</code>
&lt;/xsl:stylesheet&gt;<a name="wp65106"> </a>
</pre></div>
<a name="wp65107"> </a><p class="pBody">
This code brings up an interesting issue that results from the inclusion of the <code class="cCode">&lt;br/&gt;</code> tag. To be well-formed XML, the tag must be specified in the stylesheet as <code class="cCode">&lt;br/&gt;</code>, but that tag is not recognized by many browsers. And while most browsers recognize the sequence <code class="cCode">&lt;br&gt;&lt;/br&gt;</code>, they all treat it like a paragraph break, instead of a single line break.
</p>
<a name="wp65108"> </a><p class="pBody">
In other words, the transformation <span style="font-style: italic">must</span> generate a <code class="cCode">&lt;br&gt;</code> tag, but the stylesheet must specify <code class="cCode">&lt;br/&gt;</code>. That brings us to the major reason for that special output tag we added early in the stylesheet:
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
&lt;xsl:stylesheet ... &gt;
&nbsp;&nbsp;<code class="cCodeBold">&lt;xsl:output method=&quot;html&quot;/&gt;
</code>&nbsp;&nbsp;...
&lt;/xsl:stylesheet&gt;<a name="wp65109"> </a>
</pre></div>
<a name="wp65110"> </a><p class="pBody">
That output specification converts empty tags like <code class="cCode">&lt;br/&gt;</code> to their HTML form, <code class="cCode">&lt;br&gt;,</code> on output. That conversion is important, because most browsers do not recognize the empty tags. Here is a list of the affected tags:
</p>
<div class="pPreformattedRelative"><pre class="pPreformattedRelative">
area&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;frame&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;isindex
base&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;hr&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;link
basefont&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;img&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;meta
br&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;input&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;param
col<a name="wp78807"> </a>
</pre></div>
<a name="wp65136"> </a><p class="pBody">
To summarize, by default XSLT produces well-formed XML on output. And since an XSL stylesheet is well-formed XML to start with, you cannot easily put a tag like <code class="cCode">&lt;br&gt;</code> in the middle of it. The &quot;<code class="cCode">&lt;xsl:output method=&quot;html&quot;/&gt;</code>&quot; solves the problem, so you can code <code class="cCode">&lt;br/&gt;</code> in the stylesheet, but get <code class="cCode">&lt;br&gt;</code> in the output.
</p>
<a name="wp65137"> </a><p class="pBody">
The other major reason for specifying <code class="cCode">&lt;xsl:output method=&quot;html&quot;/&gt; </code>is that, as with the specification <code class="cCode">&lt;xsl:output method=&quot;text&quot;/&gt;</code>, generated text is <span style="font-style: italic">not</span> escaped. For example, if the stylesheet includes the <code class="cCode">&amp;lt;</code> entity reference, it will appear as the <code class="cCode">&lt;</code> character in the generated text. When XML is generated, on the other hand, the <code class="cCode">&amp;lt;</code> entity reference in the stylesheet would be unchanged, so it would appear as <code class="cCode">&amp;lt;</code> in the generated text.
</p>
<hr>
<a name="wp65138"> </a><p class="pNote">
Note: If you actually want <code class="cCode">&amp;lt;</code> to be generated as part of the HTML output, you'll need to encode it as <code class="cCode">&amp;amp;lt;</code>--that sequence becomes <code class="cCode">&amp;lt;</code> on output, because only the <code class="cCode">&amp;amp;</code> is converted to an <code class="cCode">&amp;</code> character.
</p>
<hr><a name="wp65139"> </a><h4 class="pHeading3">
Run the Program
</h4>
<a name="wp65140"> </a><p class="pBody">