谓词指定用方括号括起来的XPath表达式。在某些情况下, 它用于限制节点集中的选定节点。请参见”雇员”示例中的谓词用法。
employee.xml
<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "employee.xsl"?>
<class>
<employee id = "001">
<firstname>Abhiram</firstname>
<lastname>Kushwaha</lastname>
<nickname>Manoj</nickname>
<salary>15000</salary>
</employee>
<employee id = "002">
<firstname>Akash</firstname>
<lastname>Singh</lastname>
<nickname>Bunty</nickname>
<salary>25000</salary>
</employee>
<employee id = "003">
<firstname>Brijesh</firstname>
<lastname>Kaushik</lastname>
<nickname>Ballu</nickname>
<salary>20000</salary>
</employee>
<employee id = "004">
<firstname>Zoya</firstname>
<lastname>Mansoori</lastname>
<nickname>Sonam</nickname>
<salary>30000</salary>
</employee>
</class>| Index | Predicate | Description |
|---|---|---|
| 1) | /class/employee[1] | 它将选择第一个employee元素, 它是class元素的子元素。 |
| 2) | /class/employee[last()] | 它将选择为class元素的子元素的最后一个employee元素。 |
| 3) | / class / employee [@id = 002] | 它将选择id为002的员工元素。 |
| 4) | / class / salary [salary> 10000] | 它将选择薪金大于10000的员工元素。 |
XPath谓词示例
让我们以一个示例为例, 通过遍历每个员工来创建一个<employee>元素及其详细信息的表。本示例使用谓词计算雇员节点的位置, 然后打印雇员详细信息。
employee.xml
<?xml version = "1.0"?>
<?xml-stylesheet type = "text/xsl" href = "employee.xsl"?>
<class>
<employee id = "001">
<firstname>Abhiram</firstname>
<lastname>Kushwaha</lastname>
<nickname>Manoj</nickname>
<salary>15000</salary>
</employee>
<employee id = "002">
<firstname>Akash</firstname>
<lastname>Singh</lastname>
<nickname>Bunty</nickname>
<salary>25000</salary>
</employee>
<employee id = "003">
<firstname>Brijesh</firstname>
<lastname>Kaushik</lastname>
<nickname>Ballu</nickname>
<salary>20000</salary>
</employee>
<employee id = "004">
<firstname>Zoya</firstname>
<lastname>Mansoori</lastname>
<nickname>Sonam</nickname>
<salary>30000</salary>
</employee>
</class>员工.xsl
<?xml version = "1.0" encoding = "UTF-8"?>
<xsl:stylesheet version = "1.0"
xmlns:xsl = "http://www.w3.org/1999/XSL/Transform">
<xsl:template match = "/">
<html>
<body>
<h2>Employee</h2>
<table border = "1">
<tr bgcolor = "pink">
<th>ID</th>
<th>First Name</th>
<th>Last Name</th>
<th>Nick Name</th>
<th>Salary</th>
</tr>
<xsl:for-each select = "/class/employee[1]">
<tr>
<td><xsl:value-of select = "@id"/></td>
<td><xsl:value-of select = "firstname"/></td>
<td><xsl:value-of select = "lastname"/></td>
<td><xsl:value-of select = "nickname"/></td>
<td><xsl:value-of select = "salary"/></td>
</tr>
</xsl:for-each>
<xsl:for-each select = "/class/employee[last()]">
<tr>
<td><xsl:value-of select = "@id"/></td>
<td><xsl:value-of select = "firstname"/></td>
<td><xsl:value-of select = "lastname"/></td>
<td><xsl:value-of select = "nickname"/></td>
<td><xsl:value-of select = "salary"/></td>
</tr>
</xsl:for-each>
<xsl:for-each select = "/class/employee[@id = 002]">
<tr>
<td><xsl:value-of select = "@id"/></td>
<td><xsl:value-of select = "firstname"/></td>
<td><xsl:value-of select = "lastname"/></td>
<td><xsl:value-of select = "nickname"/></td>
<td><xsl:value-of select = "salary"/></td>
</tr>
</xsl:for-each>
<xsl:for-each select = "/class/employee[salary > 10000]">
<tr>
<td><xsl:value-of select = "@id"/></td>
<td><xsl:value-of select = "firstname"/></td>
<td><xsl:value-of select = "lastname"/></td>
<td><xsl:value-of select = "nickname"/></td>
<td><xsl:value-of select = "salary"/></td>
</tr>
</xsl:for-each>
</table>
</body>
</html>
</xsl:template>
</xsl:stylesheet>输出
注意：在上面的示例中, 你可以看到所有四个查询均已提取。
