gailcloutier

1. Overview

1) What is JSP tag

As the name suggests, JSP tag is used in the JSP file tags. It is similar to html syntax tags, like head, table. JSP file referenced by it (like using the html tags do), can be more convenient to realize the reuse of Java code modules.

2) Why use JSP tag technology (compared with javabean)

Benefits:

JSP JSP tag can handle the content of the body, such as changing the text display style; and javabean not.

JSP tag interface is simple, easy to use, but also easy to develop and maintain.

Disadvantages:

JSP tag javabean complicated than making a lot of settings, reflected in the JSP tag library description file (*. tld) in the configuration.

JSP tag to achieve so much as javabean strong.

As long as JSP1.1 support current JSP tags, and JSP1.0 and 1.1 support the use of the Bean.

2.JSP marked development profile.

JSP tag development need to write 2 separate files. One is the definition of tagging the java class files, one is the xml element name (tag) mapped to the probe in the tag library descriptor file.

??write JSP tag handler class files

Need to inherit javax.servlet.jsp.tagext.TagSupport class;

Simple example:

/ / File Name ExampleTag.java importjavax.servlet.jsp .*; importjavax.servlet.jsp.tagext .*; importjava.io .*; publicclassExampleTagextendsTagSupport (/ / program execution starting point publicintdoStartTag () (try (JspWriterout = pageContext. getOut (); out.print (”Customtagexample”);) catch (IOExceptionioe) (System.out.println (”ErrorinExampleTag:” + ioe);) return (SKIP_BODY); / / when the tag includes the contents of the empty return SKIP_BODY, said tagging / / has been executed))

Compiled class file will be located in a specific server location.

??write JSP tag library descriptor file

Will mark the function name and its representatives to achieve together.

Simple example:

< ! - File Name: csajsp-taglib.tld-->; < ? Xmlversion = "1.0" encoding = "ISO-8859-1"?>; < ! DOCTYPEtaglib PUBLIC "- / / SunMicrosystem, Inc. / / DTDJSPTagLibrary1 .1 / / EN "http://java.sun.com/j2ee/dtds/web-jsptaglibrary_1_1.dtd>; / / These are the standard file header / / The following is a tag library description ; 1.0 ; / / Tag Library version ; 1.1 ; / / JSP version of the library ; csajsp ; / / custom tag prefix name ; ; / / tag descriptor file uri, can be empty ; Mycustomtag! ; / / tag library description of the information / / the following definition of new tags ; ; example ; / / custom tag name ; tags.ExampleTag ; / / orientation label processing class files ; Simplestexample ; / / descriptions ; EMPTY ; / / JSP file does not process the body content ; ;

This file will configure a specific location on the server

??use the above custom JSP tags

< ! - File Name: simpleExample.jsp-->; < ! DOCTYPEHTMLPUBLIC "- / / W3C / / DTDHTML4.0Transitional / / EN">; ; ; < % @ tagliburi = "csajsp-taglib . tld "prefix =" csajsp "%>;// use a statement to mark