JSP2.0中为了简化标签的复杂性，增加了制作Simple Tag的标签类SimpleTagSupport类。SimpleTagSupport类是实现SimpleTag接口的。它只需要实现一个doTag()方法即可，而不需要一堆回传值。
举例说明：
例1：HelloSimpleTag标签
第一步：制作标签处理类
AddSimpleTag.java
package com.newould.taglib;import java.io.*;import javax.servlet.jsp.*;import javax.servlet.jsp.tagext.*;public class AddSimpleTag extends SimpleTagSupport {private int num1 = 0; private int num2 = 0;public void setNum1(int num1) {this.num1 = num1;}public void setNum2(int num2) {this.num2 = num2;}public void doTag() throws JspException, IOException {JspContext ctx = getJspContext();JspWriter out = ctx.getOut();int sum = num1 + num2;ctx.setAttribute("sum", Integer.toString(sum));out.println(num1 + " + " + num2 + " = " + sum);}}
第二步：编写标签性质文件
MyTaglib.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 web-jsptaglibrary_2_0.xsd"version="2.0"><description>My Taglib by JavaWorld.com.tw</description><tlib-version>1.0</tlib-version><jsp-version>2.0</jsp-version><short-name>Mytaglib</short-name><uri></uri><tag><description>Add Simple Tag</description><name>Add</name><tag-class>com.newould.taglib.AddSimpleTag</tag-class><body-content>empty</body-content><attribute><name>num1</name><required>true</required><rtexprvalue>true</rtexprvalue></attribute><attribute><name>num2</name><required>true</required><rtexprvalue>true</rtexprvalue></attribute></tag></taglib>
第三步：编写Jsp网页
HelloSimpleTag.jsp
<%@ page contentType="text/html;charset=GB2312" %><%@ taglib uri="/WEB-INF/tlds/MyTaglib.tld" prefix="mytag" %><html><head><title>HelloSimpleTag.jsp</title></head><body><h2>Simple Tag 标签</h2><h1><mytag:HelloSimpleTag /></h1></body></html>
例2：AddSimpleTag标签
第一步：制作标签处理类
HelloSimpleTag.java
package com.newould.taglib;import java.io.*;import javax.servlet.jsp.*;import javax.servlet.jsp.tagext.*;public class HelloSimpleTag extends SimpleTagSupport {public void doTag() throws JspException, IOException {JspWriter out = getJspContext().getOut();out.println("Hello Simple Tag");}}
第二步：编写标签性质文件
MyTaglib.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 web-jsptaglibrary_2_0.xsd"version="2.0"><description>My Taglib by JavaWorld.com.tw</description><tlib-version>1.0</tlib-version><jsp-version>2.0</jsp-version><short-name>Mytaglib</short-name><uri></uri<tag><description>Hello Simple Tag</description><name>HelloSimpleTag</name><tag-class>com.newould.taglib.HelloSimpleTag</tag-class><body-content>empty</body-content></tag></taglib>
第三步：编写Jsp网页
AddSimpleTag.jsp
<%@ page contentType="text/html;charset=GB2312" %><%@ taglib uri="/WEB-INF/tlds/MyTaglib.tld" prefix="mytag" %><html><head><title>AddSimpleTag.jsp</title></head><body><h2>AddSimpleTag 标签</h2><h1><mytag:Add num1="5" num2="9" /></h1>最后结果：${sum}</body></html>
例3 RepeatSimpleTag标签
RepeatSimpleTag标签 主要是用来重复显示某段文字。
这个例子在处理上与前两个例子有点不同
第一步：制作标签处理类
RepeatSimpleTag.java
package com.newould.taglib;import java.io.*;import javax.servlet.jsp.*;import javax.servlet.jsp.tagext.*;public class RepeatSimpleTag extends SimpleTagSupport {private int count = 0;//重复的次数private JspFragment fragment;//重复的内容public void setCount(int count) {this.count = count;}public void setFragment(JspFragment fragment) {this.fragment = fragment;}public void doTag() throws JspException, IOException {JspContext ctx = getJspContext();JspWriter out = ctx.getOut();for(int i=0 ; i<count ; i++) {fragment.invoke(null);//表示将fragment的内容显示出来}}}
第二步：编写标签性质文件
MyTaglib.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 web-jsptaglibrary_2_0.xsd"version="2.0"><description>My Taglib by JavaWorld.com.tw</description><tlib-version>1.0</tlib-version><jsp-version>2.0</jsp-version><short-name>Mytaglib</short-name><uri></uri><tag><description>Repeate Simple Tag</description><name>Repeat</name><tag-class>com.newould.taglib.RepeatSimpleTag</tag-class><body-content>empty</body-content><attribute><name>count</name><required>true</required><rtexprvalue>true</rtexprvalue></attribute><attribute><name>fragment</name><required>true</required><fragment>true</fragment></attribute> </tag> </taglib>
注意：<fragment>true</fragment>，一定要这样设定fragment属性。
第三步：编写Jsp网页
RepeatSimpleTag.jsp
<%@ page contentType="text/html;charset=GB2312" %><%@ taglib uri="/WEB-INF/tlds/MyTaglib.tld" prefix="mytag" %><html><head><title>RepeatSimpleTag.jsp</title></head><body><h2>RepeatSimpleTag 标签</h2><mytag:Repeat count="5" ><jsp:attribute name="fragment">重复执行 ....<br></jsp:attribute></mytag:Repeat></body></html>
DynamicAttributes接口
只要制作的标签实现了DynamicAttributes接口就有动态属性的功能。
例如:我们要做多个数的累加运算,则AddSimpleTag标签就可以通过实现DynamicAttributes接口就可以实现了.
实现DynamicAttributes接口,必须实现setDynamicAttributes()方法,此方法用来接收动态属性.
举例:第一步：制作标签处理类
package com.newould.taglib;import java.io.*;import java.util.*;import javax.servlet.jsp.*;import javax.servlet.jsp.tagext.*;public class DynamicAdd extends SimpleTagSupport implements DynamicAttributes {//用来接收动态属性private ArrayList keys = new ArrayList();private ArrayList values = new ArrayList();public void doTag() throws JspException, IOException {JspContext ctx = getJspContext();JspWriter out = ctx.getOut();float num = 0;float sum = Float.parseFloat((String)values.get(0));out.print(sum); for (int i = 1 ; i < keys.size() ; i++) {String temp = (String)values.get(i);num = Float.parseFloat(temp);sum = sum + num; out.print(" + " + num);}out.print(" = " + sum);ctx.setAttribute("sum", Float.toString(sum));}public void setDynamicAttribute(String uri, String name, Object value) throws JspException {keys.add(name);values.add(value);}}
第二步：编写标签性质文件
<tag><description>DynamicAttribute</description><name>DynAdd</name><tag-class>com.newould.taglib.DynamicAdd</tag-class><body-content>empty</body-content><dynamic-attributes>true</dynamic-attributes></tag>
第三步：编写Jsp网页
<%@ page contentType="text/html;charset=GB2312" %><%@ taglib prefix="JSPBook" tagdir="/WEB-INF/tags/" %><%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %><html><head><title>CH16 - DynAdd.jsp</title></head><body><h2>Tag File 范例</h2><JSPBook:DynAdd num1="111" num2="222" num3="444" ><jsp:attribute name="great"><font color="red">SUM：${sum} ...</red></jsp:attribute><jsp:attribute name="less"><font color="blue">SUM：${sum} ...</red></jsp:attribute></JSPBook:DynAdd></body></html>
相关资源：JSP2.0技术手册pdf(带示例源码).zip
