JSP自定义标签

创建自定义标签分以下几步：

1. 扩展javax.servlet.jsp.tagext.TagSupport类并编译打包到WEB-INF/lib目录

2. 编写标签的tld文件

3. 在web.xml中指定tld文件(如果把tld文件放到自定义标签的jar包中，该步可以省略)

4. 在jsp中调用该标签


1. 创建com.john.jsp.tags.MyFirstTag类:

需要添加对jsp-api-[version number]-glassfish-[version number].[version time].jar的引用

public class MyFirstTag extends TagSupport {
	@Override
	public int doStartTag() throws JspException {
		JspWriter writer = pageContext.getOut();
		try {
			writer.println("Hello world!");
		} catch (IOException e) {
			e.printStackTrace();
		}
		return SKIP_BODY;
	}
}

编译并打包成jar文件放到WEB-INF/lib目录下。

2. 编写firstag.tld文件：

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "web-jsptaglibrary_1_2.dtd">
<taglib>
	<tlib-version>1.0</tlib-version>
	<jsp-version>1.2</jsp-version>
	<short-name>Significant</short-name>
	<!-- It's acceptable to define the uri within the web.xml, the uri is unnecessarily reachable but necessarily unique -->
	<uri>http://czj4451.iteye.com/firsttag</uri>
	<tag>
		<name>myfirsttag</name>
		<!-- The full class name is case-sentitive -->
		<tag-class>com.john.jsp.tags.MyFirstTag</tag-class>
	</tag>
</taglib>

3. 在web.xml中添加：

<jsp-config>
	<taglib>
		<taglib-uri>http://czj4451.iteye.com/firsttag</taglib-uri>
		<taglib-location>/WEB-INF/tlds/firsttag.tld</taglib-location>
	</taglib>
</jsp-config>

4. 创建tag.jsp：

<%@ taglib uri="http://czj4451.iteye.com/firsttag" prefix="firsttag" %>

<firsttag:myfirsttag/>