Jsp_demo: Custom Labels

JSP Custom Tags:

1. Inherit simpletagsupport, rewrite Dotag ().

2. Configure the **.tld file under web-inf/

3.JSP page Introduction to Custom Tags: <%@ taglib uri= "* * *" prefix= "s"%>

Custom Label Demo implementation: On the JSP page, save the object in Pagecontext.setattribute () and use the label to output all methods, member variables, and values of the object.

Testtag.java:

 PackageMyTag;Importjava.io.IOException;ImportJava.io.Writer;ImportJava.lang.reflect.Field;ImportJava.lang.reflect.Method;ImportJavax.servlet.jsp.tagext.SimpleTagSupport; Public classTesttagextendssimpletagsupport{PrivateString obj;//with attribute tags the corresponding setter and getter methods must be provided for each property     PublicString getobj () {returnobj; }     Public voidsetobj (String obj) { This. obj =obj; }     Public voidDotag ()throwsioexception{Writer out=Getjspcontext (). Getout (); Object Object=(Object) Getjspcontext (). getattribute (obj); Class<?> c=Object.getclass (); Field fields[]=C.getdeclaredfields ();  for(Field f:fields) {f.setaccessible (true);//Private members can also access            Try{out.write (F.getname ()+ ":" +f.get (object) + "</br>"); } Catch(IllegalArgumentException |illegalaccessexception e)            {E.printstacktrace (); }} Method methods[]=C.getmethods ();  for(Method m:methods) {out.write (m.tostring ()+ "</br>"); }    }}

MYTAGLIB.TLD:

<?XML version= "1.0" encoding= "Iso-8859-1"?><!DOCTYPE taglib Public "-//sun Microsystems, Inc.//dtd JSP Tag Library 1.2//en" "Http://java.sun.com/j2ee /dtd/web-jsptaglibrary_1_2.dtd "><taglib>  <tlib-version>1.0</tlib-version>  <jsp-version>1.2</jsp-version>  <Short-name>Mytaglib</Short-name>  <URI>/mytaglib</URI>  <Tag>    <!--Define label names -    <name>Info</name>    <!--defining label Handling classes -    <Tag-class>MyTag. Testtag</Tag-class>    <!--define the label body as empty -    <body-content>Empty</body-content>    <!--Configuration Label Properties: Driver -    <attribute>        <name>Obj</name>         <Required>True</Required>        <Fragment>True</Fragment>    </attribute>     </Tag></taglib>

TEST.JSP:

<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "    pageencodingImport=" MyTag. User,java.util.* "%>    <%@ taglib uri="/mytaglib "prefix=" s "%><! DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "Http://www.w3.org/TR/html4/loose.dtd" >    Pagecontext.setattribute (new  Date ()); %><b><s:hello/></b><b><s:info obj= "Date"/></b></body>
Jsp_demo: Custom Labels