自定义标签出现空指针错误

各位大神求助，在用自定义标签时，出现空指针错误，报错如下：

org.apache.jasper.JasperException: java.lang.NullPointerException

	org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:538)

	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:370)

	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)

	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:723)





root cause 



java.lang.NullPointerException

	org.apache.jsp.page.defineTag_jsp._jspInit(defineTag_jsp.java:30)

	org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:52)

	org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:164)

	org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:340)

	org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313)

	org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260)

	javax.servlet.http.HttpServlet.service(HttpServlet.java:723)

action代码：

package action;



import javax.servlet.jsp.JspException;

import javax.servlet.jsp.JspWriter;

import javax.servlet.jsp.tagext.TagSupport;



public class HelloAction extends TagSupport {



	/**

	 * 

	 */

	private static final long serialVersionUID = -6010459496748855933L;

	private String name = null;



	public void setName(String name) {

		this.name = name;

	}



	@Override

	public int doStartTag() throws JspException {

		

		try {

			JspWriter out = pageContext.getOut();

			out.print("Hello!"+name);

		} catch (Exception e) {

			e.printStackTrace();

		}

		return EVAL_PAGE;

	}

}

tld代码：

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

<!DOCTYPE taglib PUBLIC "-//Sun Microsystems, Inc.//DTD JSP Tag Library 1.2//EN" "http://java.sun.com/dtd/web-jsptaglibrary_1_2.dtd" >

<taglib>

  <tlib-version>1.0</tlib-version>

  <jsp-version>1.2</jsp-version>

  <short-name>msp</short-name>

  <tag>

    <name>out</name>

    <tag-class>org.msp.action.HelloAction</tag-class>

    <body-content>empty</body-content>

    <attribute>

    	<name>name</name>

    	<required>false</required>

    	<rtexprvalue>false</rtexprvalue>

    </attribute>

  </tag>

</taglib>

JSP代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@taglib uri="/WEB-INF/tlds/hello.tld" prefix="m"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

	测试标签:<m:out name="自定义标签"/>

</body>

</html>

web.xml配置：

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

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

  <display-name>tag</display-name>

  

  <jsp-config>

  	<taglib>

  		<taglib-uri>/WEB-INF/tlds/hello.tld</taglib-uri>

  		<taglib-location>/WEB-INF/tlds/hello.tld</taglib-location>

  	</taglib>

  </jsp-config>

  <welcome-file-list>

    <welcome-file>page/defineTag.jsp</welcome-file>

    <welcome-file>index.htm</welcome-file>

    <welcome-file>index.jsp</welcome-file>

    <welcome-file>default.html</welcome-file>

    <welcome-file>default.htm</welcome-file>

    <welcome-file>default.jsp</welcome-file>

  </welcome-file-list>

</web-app>

自定义标签空指针 --------------------编程问答-------------------- package action;
<tag-class>org.msp.action.HelloAction</tag-class>
你包名里没有这个红色的吧。 --------------------编程问答--------------------

引用 1 楼 fangmingshijie 的回复:

package action;
<tag-class>org.msp.action.HelloAction</tag-class>
你包名里没有这个红色的吧。

我把包名写错了，不过改回来还是一样报空指针。

补充：Java ,  Web 开发