Custom Label (JSTL)

To customize a label:

1, determine the requirements, such as: with <my:date/> output current time

2, write Java class: Need to Implement Interface Javax.servlet.jsp.tagext.JspTag

The specific interfaces are:

Javax.servlet.jsp.tagext.SimpleTag, simple label, jsp2.0**
Javax.servlet.jsp.tagext.Tag, classic label

3. Writing TDL file (XML)

Demo:

1  Public classMyTagImplementsSimpletag {2     3     PrivatePageContext PageContext;4      Public voidsetjspcontext (Jspcontext pc) {5         6          This. pagecontext=(PageContext) pc;//settings PageContext7     }8     9      Public voidDotag ()throwsjspexception, IOException {Ten          OneSimpleDateFormat format=NewSimpleDateFormat ("Yyyy-mm-dd Hh:mm:ss:SSS"); AString Date=format.format (NewDate ()); - pagecontext.getout (). print (date);//output to page -     } the  -      PublicJsptag getParent () { -         //TODO auto-generated Method Stub -         return NULL; +     } -  +      Public voidsetjspbody (jspfragment arg0) { A         //TODO auto-generated Method Stub at          -}

1 <?XML version= "1.0" encoding= "UTF-8"?>2 3 <taglibxmlns= "Http://java.sun.com/xml/ns/javaee"4 Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"5 xsi:schemalocation= "Http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"6 version= "2.1">

<!--determine the version of the current tag library--7     <tlib-version>1.0</tlib-version>8     <Short-name>My</Short-name> <!--recommended to introduce the current note library is, using the shorthand-- 9     <URI>Http://www.cnblogs.com/liuwt365/mytag</URI> <!--as the current tag library profile, starting with a name * content: Custom, globally unique--- Ten      One     <Tag> A         <name>Date</name> <!--determine label name -- -         <Tag-class>Cn.test.simpleTag.MyTag</Tag-class> <!--determining the implementation class -- -         <body-content>Empty</body-content> <!--formatting the body contents of the current tag-- the     </Tag> -  - </taglib>

1 <%@ taglib URI="Http://www.cnblogs.com/liuwt365/mytag"prefix="my" %> <!--page Registration --2 3 <my:date/>

PS: If the label contains attributes, you need to set it in TDL: <my:maxvalue num1= "num2=" ></my:maxValue>

　　

1 <Tag>2         <name>Max</name>3         <Tag-class>Cn.test.simpleTag.MyMaxTag</Tag-class>4         <body-content>Empty</body-content>5         <attribute>6             <name>Num1</name>7             <Required>True</Required>8             <Rtexprvalue>True</Rtexprvalue>9             <type>Java.lang.Integer</type>Ten         </attribute> One          A         <attribute>//Setting Properties -             <name>Num2</name>//Property name -             <Required>True</Requiredwhether >//must be True|false (Yes|no) (not required) the             <Rtexprvalue>True</Rtexprvalue>//runtime expression value run-time expressions -             <type>Java.lang.Integer</type>//Type (not required) -         </attribute> -     </Tag>

If the label body is included, the following:<my:toupper>juhjdksds</my:toupper> are set in TDL

<Tag>        <name>ToUpper</name>        <Tag-class>Cn.test.simpleTag.MyToUpperTag</Tag-class>        <body-content>Scriptless</body-content>

<!--determine the type of label body
* Empty: No label body
* JSP: Support all JSP syntax, use in tag
* Scriptless: Scripts for JSP pages do not support <%%>
* Tagdependent: The label body does not do the processing, the original output
-
     </Tag>

If the tag body is included, the Java class

1  Public void setjspbody (jspfragment JF) {2         this. jspfragment=JF;   Get      3     }

When outputting to a JSP page

 1  stringwriter stringwriter=new  StringWriter (); //  get stream  2  this . Jspfragment.invoke (StringWriter); //  writes data to the stream  4  String data=stringwriter.tostring (). toUpperCase ();  5  this  .pagecontext.getout (). print (data);  7  

This.jspFragment.invoke(pagecontext.getout ()) =This.jspFragment.invoke ();

Custom Label (JSTL)