el静态方法错误

只要添加tld文件就会出错
<?xml version="1.0" encoding="UTF-8"?>
<taglib xmlns="http://java.sun.com/xml/ns/javaee"
        xmlns:xsi="http://www.w3.org/2001/XMNLSchema-instance"
        xsi:schemaLocation="http://java.sun.com/xml/ns/javaee/web-jsptaglibrary_2_1.xsd"
        version="2.1">
        <tilb-version>1.0</tilb-version>
        <description>用于转换特殊字符</description>
        <uri>myelfun</uri>
        <function>
                <name>ps</name>
                <function-clasas>webdemo3.chapter05.ELFun</function-clasas>
                <function-signature>
                        java.lang.String processStr(java.lang.String)
                </function-signature>
        </function>
</taglib>

控制台错误：

java.lang.IllegalArgumentException: Can't convert argument: null
        at org.apache.tomcat.util.IntrospectionUtils.convert(IntrospectionUtils.java:434)
        at org.apache.tomcat.util.digester.CallMethodRule.end(CallMethodRule.java:371)
        at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:956)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:609)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1781)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2957)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
        at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:117)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
        at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
        at com.sun.org,apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:649)
        at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1451)
        at org.apache.tomcat.util.descriptor.tld.TldParser.parse(TldParser.java:76)
        at org.apache.jasper.servlet.TldScanner.scanJspConfig(TldScanner.java:198)
        at org.apache.jasper.servlet.TldScanner.scan(TldScanner.java:104)
        at org.apache.jasper.servlet.JasperInitializer.onStartup(JasperInitializer.java:103)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5156)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1399)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:744)

九月 09, 2015 8:39:01 下午 org.apache.catalina.core.StandardContext startInternal
严重: Error during ServletContainerInitializer processing
javax.servlet.ServletException: org.xml.sax.SAXParseException; systemId: file:/C:/apache-tomcat-8.0.23/wtpwebapps/webdemo3/WEB-INF/tld/elfun.tld; lineNumber: 15; columnNumber: 13; Error at (15, 13) : Can't convert argument: null
        at org.apache.jasper.servlet.JasperInitializer.onStartup(JasperInitializer.java:105)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5156)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1409)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1399)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:744)
Caused by: org.xml.sax.SAXParseException; systemId: file:/C:/apache-tomcat-8.0.23/wtpwebapps/webdemo3/WEB-INF/tld/elfun.tld; lineNumber: 15; columnNumber: 13; Error at (15, 13) : Can't convert argument: null
        at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:1908)
        at org.apache.tomcat.util.digester.Digester.createSAXException(Digester.java:1940)
        at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:959)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.endElement(AbstractSAXParser.java:609)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanEndElement(XMLDocumentFragmentScannerImpl.java:1781)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl$FragmentContentDriver.next(XMLDocumentFragmentScannerImpl.java:2957)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentScannerImpl.next(XMLDocumentScannerImpl.java:606)
        at com.sun.org.apache.xerces.internal.impl.XMLNSDocumentScannerImpl.next(XMLNSDocumentScannerImpl.java:117)
        at com.sun.org.apache.xerces.internal.impl.XMLDocumentFragmentScannerImpl.scanDocument(XMLDocumentFragmentScannerImpl.java:510)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:848)
        at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(XML11Configuration.java:777)
        at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(XMLParser.java:141)
        at com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1213)
        at com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:649)
        at org.apache.tomcat.util.digester.Digester.parse(Digester.java:1451)
        at org.apache.tomcat.util.descriptor.tld.TldParser.parse(TldParser.java:76)
        at org.apache.jasper.servlet.TldScanner.scanJspConfig(TldScanner.java:198)
        at org.apache.jasper.servlet.TldScanner.scan(TldScanner.java:104)
        at org.apache.jasper.servlet.JasperInitializer.onStartup(JasperInitializer.java:103)
        ... 8 more
Caused by: java.lang.IllegalArgumentException: Can't convert argument: null
        at org.apache.tomcat.util.IntrospectionUtils.convert(IntrospectionUtils.java:434)
        at org.apache.tomcat.util.digester.CallMethodRule.end(CallMethodRule.java:371)
        at org.apache.tomcat.util.digester.Digester.endElement(Digester.java:956)
        ... 24 more


jsp页面错误：
HTTP Status 404 - /webdemo3/chapter5/elfun.jsp

type Status report

message /webdemo3/chapter5/elfun.jsp

description The requested resource is not available.


我找了三个例子，每个写法都不同。到底该怎么写？tld文件taglib标签属性值是不是应该会和web.xml文档中的web-app标签的属性一致？此例不一致。