Uso de XML/XSLT

O que são XSL e XSLT?

            - XSL Transformations (XSLT): Uma linguagem para transformar XML.
            - XML Path Language (XPath): Uma linguagem para acessar e referir a partes de um documento XML.
            - XSL Formatting Objects (XSL-FO): Um vocabulário XML para especificar semântica de formatação.

XML e XSLT

<employee id="03432">
 <name>Joe Shmo</name>
 <title>Manager</title>
</employee>
<html>
 <body>
 <p><b>Joe Shmo</b>: Manager</p>
 </body>
</html>
<xsl:stylesheet xmlns:xsl="">
 <xsl:template match="/">
 <html>
 <body>
 <p>
 <b>
 <xsl:value-of select="employee/name"/>
 </b>
 <xsl:text>: </xsl:text>
 <xsl:value-of select="employee/title"/>
 </p>
 </body>
 </html>
 </xsl:template>
</xsl:stylesheet>

Comandos XSL básicos

Declaração de stylesheet

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
.
.
.
</xsl:stylesheet>
xmlns:java="http://xml.apache.org/xslt/java"

Casamento de padrões

<employee id="03432">
 <name>Joe Shmo</name>
 <title>Manager</title>
</employee>

Templates 

<xsl:template match="nodename">
.
.
.
</xsl:template>
<xsl:apply-templates select="nodename"/>
<xsl:template match="name"
 <xsl:value-of select="..."/>
</xsl:template>
<xsl:apply-templates select="name"/>

Comandos Lógicos

Comando Choose

<xsl:choose>
 <xsl:when test="test situation">
 stylesheet commands
 </xsl:when>
 <xsl:otherwise>
 stylesheet commands
 </xsl:otherwise>
</xsl:choose>
<xsl:otherwise/>

Command  if

<xls:if test="test situation">
...
</xsl:if>

Laços (comando for-each) 

<xsl:for-each select="select statement">
...
</xsl:for-each>
<xsl:for-each select="employee[title='Manager']">
...
</xsl:for-each>

Variáveis

<xsl:variable name="count">atribuir valor a count aqui</xsl:variable>
<xsl:value-of select="$count"/>

Parâmetros

<xsl:param name="param1" select="'default value'"/>
 transformer.setParameter("param1", "default value");

Extensões

xmlns:java="http://xml.apache.org/xslt/java"

A API do XSLT da JRE

Class javax.xml.transform.Transformer

Class javax.xml.transform.Source

Class javax.xml.transform.Result

Um exemplo completo

<!ELEMENT orders (invoice)+>
<!ELEMENT invoice (item+,name,address+)>
<!ELEMENT item EMPTY>
<!ELEMENT name (#PCDATA)>
<!ELEMENT address (street, city, state, zip)>
<!ELEMENT street (#PCDATA)>
<!ELEMENT city (#PCDATA)>
<!ELEMENT state (#PCDATA)>
<!ELEMENT zip (#PCDATA)>
<!ATTLIST invoice
 number CDATA #REQUIRED
 orderDate CDATA #REQUIRED
 shipDate CDATA #REQUIRED>
<!ATTLIST item
 part CDATA #REQUIRED
 quantity CDATA #REQUIRED
 cost CDATA #REQUIRED>
<!ATTLIST address
 type (shipping|billing|other) #REQUIRED>

A View de transações 

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:java="http://xml.apache.org/xslt/java"
 exclude-result-prefixes="java"
 version="1.0">
<xsl:output method="html" indent="yes"/>
<xsl:template match="/orders">
 <html>
 <h1>Today's Invoices</h1>
 <body>

 <table border="on" cellspacing="1" cellpadding="5">
 <thead>
 <th>Invoice Number</th>
 <th>Customer Name</th>
 <th>Total Purchase</th>
 </thead>
 <tbody>
 <xsl:for-each select="invoice">
 <tr>
 <td>
 <xsl:element name="a">
 <xsl:attribute name="href">
 <xsl:text>xsl?stylesheet=detail&invoiceNum=</xsl:text>
 <xsl:value-of select="@number"/>
 </xsl:attribute>
 <xsl:value-of select="@number"/>
 </xsl:element>
 </td>
 <td><xsl:value-of select="name"/></td>
 <td><xsl:value-of select="java:SumInvoice.summ(item)"/></td>
 </tr>
 </xsl:for-each>
 </tbody>
 </table>
 </body>
 </html>
</xsl:template>
</xsl:stylesheet>

jw-0630-xsl1.gif (38573 bytes)

A view de detalhes

<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
 xmlns:java="http://xml.apache.org/xslt/java"
 exclude-result-prefixes="java"
 version="1.0">
<xsl:param name="invoiceNum" select="string('none')"/>
<xsl:output method="html" indent="yes"/>
<xsl:template match="/">
<html>
<body>
 <table border="on" cellspacing="1" cellpadding="5">
 <xsl:for-each select="orders/invoice[@number=$invoiceNum]">
 <tr>
 <td>
 <table border="on" cellspacing="1" cellpadding="5">
 <tr>
 <td><b>Invoice Number:</b>
 <xsl:value-of select="@number"/>
 </td>
 <td colspan="3"><xsl:value-of select="name"/></td>
 </tr>
 <tr>
 <td colspan="4">
 <xsl:apply-templates select="address"/>
 </td>
 </tr>
 <tr>
 <td colspan="4"><b>Items</b>
 </td>
 </tr>
 <tr>
 <td>Part</td>
 <td>Quantity</td>
 <td>Cost</td>
 <td>Subtotal</td>
 </tr>
 <xsl:for-each select="item">
 <tr>
 <td><xsl:value-of select="@part"/></td>
 <td><xsl:value-of select="@quantity"/></td>
 <td><xsl:value-of select="@cost"/></td>
 <td><xsl:value-of select="@quantity * @cost"/></td>
 </tr>
 </xsl:for-each>
 <tr>
 <td>
 <b><xsl:text>Total</xsl:text></b>
 </td>
 <td>
 <xsl:value-of select="sum(item/@quantity)"/>
 </td>
 <td>
 <xsl:text></xsl:text>
 </td>
 <td>
 <xsl:value-of select="java:SumInvoice.summ(item)"/>
 </td>
 </tr>
 </table>
 </td>
 </tr>
 </xsl:for-each>
 </table>
 </body>
</html>
</xsl:template>
<xsl:template match="address">
<table>
 <tr>
 <td><i>
 <xsl:choose>
 <xsl:when test="@type='shipping'">
 <xsl:text>Shipping Address</xsl:text>
 </xsl:when>
 <xsl:when test="@type='billing'">
 <xsl:text>Billing Address</xsl:text>
 </xsl:when>
 <xsl:otherwise>
 <xsl:text>Other Address</xsl:text>
 </xsl:otherwise>
 </xsl:choose></i>
 </td>
 </tr>
 <tr>
 <td colspan="4">
 <xsl:value-of select="street"/>
 </td>
 </tr>
 <tr>
 <td colspan="4">
 <xsl:value-of select="city"/>
 <xsl:text> </xsl:text>
 <xsl:value-of select="state"/>,
 <xsl:value-of select="zip"/>
 </td>
 </tr>
</table>
</xsl:template>
</xsl:stylesheet>

jw-0630-xsl2.gif (47423 bytes)

O servlet

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.xml.transform.*;
import javax.xml.transform.stream.*;

public class XSLTServlet extends HttpServlet {

	public void init(ServletConfig config) throws ServletException {
	super.init(config);
	}

	// By redirecting our doGets to the doPost method we can have a stylesheet
	// executed from a link
	// ex. <a href="xsl?stylesheet=detail&invoiceNum=00002">00002
	public void doGet(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {

	doPost(request, response);
	}

	// Process the HTTP Post request
	public void doPost(HttpServletRequest request, HttpServletResponse response)
	throws ServletException, IOException {

	PrintWriter out = new PrintWriter(response.getOutputStream());

	// Get the stylesheet selected by the user
	String stylesheet = request.getParameter("stylesheet");

	// Get the invoice number selected by the user, this is used only for
	// certain
	// stylesheets. If it is not present, the stylesheet won't use it.
	String invoiceNum = request.getParameter("invoiceNum");

	// Prepare FileReaders for the stylesheet and XML
	FileReader xslReader = new FileReader(".\\javaworld\\xsl\\"
	+ stylesheet + ".xsl");
	FileReader xmlReader = new FileReader(".\\javaworld\\xml\\"
	+ "invoice.xml");

	response.setContentType("text/html");
	try {
	// Create an instance of a Transformer
	TransformerFactory transFact = TransformerFactory.newInstance();
	Transformer trans = transFact.newTransformer(new StreamSource(
	xslReader));
	// Set the invoice number parameter
	trans.setParameter("invoiceNum", invoiceNum);

	// Process the stylesheet, all the output will go straight
	// out to the browser.
	trans.transform(new StreamSource(xmlReader), new StreamResult(out));

	} catch (TransformerConfigurationException e) {
	out.write(e.getMessage());
	e.printStackTrace(out);
	} catch (TransformerException e) {
	out.write(e.getMessage());
	e.printStackTrace(out);
	}
	out.close();
	}

	// Get Servlet information
	public String getServletInfo() {
	return "XSLTServlet Information";
	}
}

Quando usar XML/XSL/XSLT?

Vantagens

Desvantagens


Exemplos

Bibliografia