JSTL Functions - The Java EE 5 Tutorial (original) (raw)
2. Using the Tutorial Examples
3. Getting Started with Web Applications
5. JavaServer Pages Technology
7. JavaServer Pages Standard Tag Library
Flow Control Tags in the Core Tag Library
Internationalization Tag Library
Further Information about JSTL
10. JavaServer Faces Technology
11. Using JavaServer Faces Technology in JSP Pages
12. Developing with JavaServer Faces Technology
13. Creating Custom UI Components
14. Configuring JavaServer Faces Applications
15. Internationalizing and Localizing Web Applications
16. Building Web Services with JAX-WS
17. Binding between XML Schema and Java Classes
19. SOAP with Attachments API for Java
21. Getting Started with Enterprise Beans
23. A Message-Driven Bean Example
24. Introduction to the Java Persistence API
25. Persistence in the Web Tier
26. Persistence in the EJB Tier
27. The Java Persistence Query Language
28. Introduction to Security in the Java EE Platform
29. Securing Java EE Applications
31. The Java Message Service API
32. Java EE Examples Using the JMS API
36. The Coffee Break Application
37. The Duke's Bank Application
JSTL Functions
Table 7-8 lists the JSTL functions.
Table 7-8 Functions
| Area | Function | Tags | Prefix |
|---|---|---|---|
| Functions | Collection length | length | fn |
| String manipulation | toUpperCase, toLowerCase substring, substringAfter, substringBefore trim replace indexOf, startsWith, endsWith, contains,containsIgnoreCase split, join escapeXml |
Although the java.util.Collection interface defines a size method, it does not conform to the JavaBeans component design pattern for properties and so cannot be accessed by using the JSP expression language. The length function can be applied to any collection supported by the c:forEach and returns the length of the collection. When applied to a String, it returns the number of characters in the string.
For example, the index.jsp page of the hello1 application introduced in Chapter 3, Getting Started with Web Applicationsuses the fn:length function and the c:if tag to determine whether to include a response page:
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %>
Hello ...<c:if test="${fn:length(param.username) > 0}" > <%@include file="response.jsp" %>
The rest of the JSTL functions are concerned with string manipulation:
- toUpperCase, toLowerCase: Changes the capitalization of a string
- substring, substringBefore, substringAfter: Gets a subset of a string
- trim: Trims white space from a string
- replace: Replaces characters in a string
- indexOf, startsWith, endsWith, contains, containsIgnoreCase: Checks whether a string contains another string
- split: Splits a string into an array
- join: Joins a collection into a string
- escapeXml: Escapes XML characters in a string
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