开发和使用JSP自定义标签过程:
import javax.servlet.jsp.tagext.Tag;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.JspException;
import java.io.*;
import javax.servlet.jsp.JspTagException;
/**
* 以实现Tag接口的方式来开发标签程序
*/
public class HelloTag
implements Tag {
private PageContext pageContext;
private Tag parent;
public HelloTag(){
super();
}
/**
* 设置标签的页面上下文
* @param pageContext
*/
public void setPageContext(PageContext pageContext) {
this.pageContext=pageContext;
}
/**
* 设置上一级标签
* @param t
*/
public void setParent(Tag parent) {
this.parent=parent;
}
public Tag getParent() {
return this.parent;
}
/**
* 开始标签时的操作
* @return
* @throws JspException
*/
public int doStartTag() throws JspException {
return this.SKIP_BODY;//返回SKIP_BODY，表示不计算标签体
}
/**
* 结束标签时的操作
* @return
* @throws JspException
*/
public int doEndTag() throws JspException {
try {
pageContext.getOut().write("Hello World!");
}
catch (IOException ex) {
throw new JspTagException("IO Error:"+ex.getMessage());
}
return this.EVAL_PAGE;
}
/**
* Release 用于释放标签程序占用的资源，比如使用了数据库连接，那么应该关闭这个连接
*/
public void release() {
}
} <?xml version="1.0" encoding="GBK"?>
<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>A tag library exercising SimpleTag handlers.</description>
<tlib-version>1.0</tlib-version>
<short-name>my</short-name>
<uri>/mytag</uri>
<description>学习标签</description>
<tag>
<description>输出Hello World</description>
<name>hello</name>
<tag-class>HelloTag</tag-class>
<body-content>empty</body-content>
</tag>
</taglib>
<web-app>
...
<taglib>
<taglib-uri>/mytag</taglib-uri>
<taglib-location>/WEB-INF/mytag.tld</taglib-location>
</taglib>
...
</web-app>
<%@ taglib uri="/mytag" prefix="hello" %>
<%@ page contentType="text/html;charset=GBK" language="java" %>
<html>
<head>
<title>first tag</title>
<meta http-equiv="Content-Type" content="text/html;charset=GBK">
</head>
<body>
<p>以下的内容从Taglib中输出显示:</p>
<p><my:hello></p>
</body>
</html>原文地址：http://blog.csdn.net/leimengyuanlian/article/details/42299455
