SpringSource Javax Servlet JSP JSP JSTL framework advanced features and expansion usage methods
SpringSource Javax Servlet JSP JSP JSTL framework advanced features and expansion usage methods
Overview:
SpringSource's Javax Service JSP JSP JSTL framework provides a method of simplifying and strengthening the development of Java Web applications.In addition to basic functions, the framework also provides many high -level characteristics and expansion usage, enabling developers to build complex web applications more efficiently.
1. Senior characteristics of label library function
The JSTL label library is one of the core components in JSP. It simplifies the process of common operations in the JSP page by providing a set of good tags and functions.The following are some of the advanced features of the JSTL label library:
1. Conditional judgment label:
JSTL provides tags of <C: if> and <c: Choose>, which can easily make conditional judgment and branch selection.With these labels, developers can perform different operations according to different conditions to achieve more flexible page control.
<c:if test="${condition}">
</c:if>
<c:choose>
<c:when test="${condition1}">
</c:when>
<c:when test="${condition2}">
</c:when>
<c:otherwise>
</c:otherwise>
</c:choose>
2. iteration label:
JSTL provides a <c: Foreach> tag, which can easily traverse the collection or array, and generate the specified HTML code in each iteration.Use the <C: Foreach> tag, and developers can easily achieve data display and processing of data.
<c:forEach items="${collection}" var="item">
</c:forEach>
3. Function library tag:
JSTL provides some built -in label libraries, where the <c: Fn> tag allows developers to use some built -in functions for string processing, date processing, and numerical processing.These functions can greatly simplify the process of data processing in the template.
<c:out value="${fn:toUpperCase(string)}" />
2. How to expand the use of custom labels
In addition to using the built -in tag library of JSTL, developers can also customize the label library to achieve more advanced functions.The following is the expansion of custom labels:
1. Create label processing class:
Developers need to create a Java class to process the logic of custom labels.This class needs to inherit from javax.servlet.jsp.tagext.tagSupport and implement dostarttag () or dondtag () method.
public class CustomTagHandler extends TagSupport {
public int doStartTag() {
}
}
2. Define the label library description file:
Developers need to create a tag library description file to define the URI and tag names of custom tags and map them to the label processing class.
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0">
<tlib-version>1.0</tlib-version>
<short-name>Custom</short-name>
<uri>http://example.com/custom</uri>
<tag>
<description>Custom Tag</description>
<name>myTag</name>
<tag-class>com.example.CustomTagHandler</tag-class>
<body-content>empty</body-content>
<attribute>
<name>attribute1</name>
<required>true</required>
</attribute>
</tag>
</taglib>
3. Use a custom tag on the JSP page:
Add a custom label statement to the beginning of the JSP page, and then you can use a custom label on the page.
<%@ taglib uri="http://example.com/custom" prefix="custom" %>
<custom:myTag attribute1="${value}" />
Summarize:
SpringSource's Javax Servlet JSP JSTL framework not only provides basic web development functions, but also provides many high -level characteristics and expansion usage, enabling developers to easily build complex web applications.By proficient in the advanced characteristics of the JSTL label library and the expansion of custom labels, developers can improve development efficiency and achieve richer functions.
