Before the example has been written, because the time relationship has not been released, this time to bring about the Taglib <tag> in the basic functions have been introduced, in taglib we found that there is a tag called <function> this brief introduction < Basic usage of function> tags what can,<function> tags do? It allows us to call a method directly in the JSP, return the specified value according to the custom method, and the compatible JSTL tag, eliminating the direct use of the <%!% in the JSP > To define the complexity of the method body invocation. If you use the El language, you'll be able to get started quickly, but the <function> tag is an El language with a method body. Note: The method defined by the function must be static, JSTL does not recognize the defined method if it is not static.
The Java code is as follows:
Package org.lxh.taglib;
Import java.util.List;
public class Functiontag {public
static string Hello (string name) {return
name;
}
public static Integer BBQ (List list) {return
list.size ();
}
}
The method must be static, and you can define a method that has a return value or a void type.
Tld:
<?xml version= "1.0" encoding= "UTF-8"?> <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 http://java.sun.com/xml/ Ns/j2ee/web-jsptaglibrary_2_0.xsd "version=" 2.0 "> <tlib-version>1.0</tlib-version> <short-name >my</short-name> <uri>http://lauedward.spaces.live.com</uri> <function> <!-- El page invoke name--> <name>hello</name> <!--Specify the processing class for the label, specifying which Java class The label is to handle. --> <function-class>org.lxh.taglib.FunctionTag</function-class> <!-- Specifies the method that is actually called in the name of the El page call. Specifies the actual method to process the class. Parameters and callback functions to write the full path--> <function-signature>java.lang.string Hello ( java.lang.String) </function-signature> </function> <function> <name>bbq</name> <f Unction-class>org.lxh.taglib.functiontag</function-class> <function-signature>java.lang.integer BBQ (java.util.List) </function-signaTure> </function> </taglib>
Note: In <function-signature> need to write the complete class name, if it is a string type must write java.lang.String such words, does not support the definition of generics such as java.util.list< Java.lang.string>eclipse will judge <> as an XML format, so omit the definition of the generic.
Jsp:
<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "
pageencoding= "UTF-8"%>
<% @taglib prefix= "My" uri= "/web-inf/tld/testfunction.tld"%>
<! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "HTTP://WWW.W3.ORG/TR/HTML4/LOOSE.DTD" >
<% @page import= "java.util.*"%><meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 ">
<title>insert title here</title>
<body>
<%
list<string> list = new arraylist<string> ();
List.add ("AA");
List.add ("BB");
List.add ("CC");
Request.setattribute ("list", "Helloword");
Request.setattribute ("name", list);
Map map = new HashMap ();
Map.put ("1", "a");
Map.put ("2", "B");
Map.put ("3", "C");
Map.put ("4", "D");
%>
<br>
${my:hello (List)}
<br>
${MY:BBQ (name)}
<br>
</body>
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