java.lang.NoClassDefFoundError: javax/el/ELResolver when running SimpleHelloByEnteringName JSF example

问题

I am new to JSF. I am using Tomcat 7.0.14 and trying to run SimpleHelloByEnteringName example but getting following errors in startup and at runtime

Startup Console message:

INFO: Deploying web application directory SimpleHelloByEnteringName
Jun 15, 2011 7:35:42 AM com.sun.faces.config.ConfigureListener contextInitialized
INFO: Initializing Mojarra 2.0.3 (FCS b03) for context '/SimpleHelloByEnteringName'
Jun 15, 2011 7:35:43 AM com.sun.faces.spi.InjectionProviderFactory createInstance
INFO: JSF1048: PostConstruct/PreDestroy annotations present.  ManagedBeans methods marked with these annotations will have said annotations processed.

**Jun 15, 2011 7:35:44 AM com.sun.faces.config.processor.NavigationConfigProcessor addNavigationCasesForRule
WARNING: JSF1058: The resource referred to by to-view-id, 'result.jsp', for navigation from '/pages/inputname.jsp', does not start with '/'.  This will be added for you, but it should be corrected.**

Jun 15, 2011 7:35:44 AM com.sun.faces.config.ConfigureListener$WebConfigResourceMonitor$Monitor <init>
INFO: Monitoring jndi:/localhost/SimpleHelloByEnteringName/WEB-INF/faces-config.xml for modifications
Jun 15, 2011 7:35:44 AM org.apache.coyote.AbstractProtocolHandler start
INFO: Starting ProtocolHandler ["http-apr-8081"]
Jun 15, 2011 7:35:44 AM org.apache.coyote.AbstractProtocolHandler start
INFO: Starting ProtocolHandler ["ajp-apr-8009"]
Jun 15, 2011 7:35:44 AM org.apache.catalina.startup.Catalina start

and runtime error when trying to run http://localhost:8081/SimpleHelloByEnteringName/

HTTP Status 500 -

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: java.lang.NoClassDefFoundError: javax/el/ELResolver
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:342)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

root cause

java.lang.NoClassDefFoundError: javax/el/ELResolver
    java.lang.ClassLoader.defineClass1(Native Method)
    java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    java.security.AccessController.doPrivileged(Native Method)
    java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    sun.misc.Launcher$ExtClassLoader.findClass(Launcher.java:229)
    java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    java.lang.ClassLoader.loadClass(ClassLoader.java:295)
    sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    java.lang.ClassLoader.loadClass(ClassLoader.java:295)
    java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    org.apache.jasper.runtime.JspFactoryImpl.getJspApplicationContext(JspFactoryImpl.java:220)
    org.apache.jsp.index_jsp._jspInit(index_jsp.java:23)
    org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:49)
    org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:171)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:356)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

root cause

java.lang.ClassNotFoundException: javax.el.ELResolver
    java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    java.security.AccessController.doPrivileged(Native Method)
    java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    sun.misc.Launcher$ExtClassLoader.findClass(Launcher.java:229)
    java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    java.lang.ClassLoader.defineClass1(Native Method)
    java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    java.security.AccessController.doPrivileged(Native Method)
    java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    sun.misc.Launcher$ExtClassLoader.findClass(Launcher.java:229)
    java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    java.lang.ClassLoader.loadClass(ClassLoader.java:295)
    sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    java.lang.ClassLoader.loadClass(ClassLoader.java:295)
    java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    org.apache.jasper.runtime.JspFactoryImpl.getJspApplicationContext(JspFactoryImpl.java:220)
    org.apache.jsp.index_jsp._jspInit(index_jsp.java:23)
    org.apache.jasper.runtime.HttpJspBase.init(HttpJspBase.java:49)
    org.apache.jasper.servlet.JspServletWrapper.getServlet(JspServletWrapper.java:171)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:356)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:333)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:722)

note The full stack trace of the root cause is available in the Apache Tomcat/7.0.14 logs.

How is this problem caused and how can I solve it?

回答1:

WARNING: JSF1058: The resource referred to by to-view-id, 'result.jsp', for navigation from '/pages/inputname.jsp', does not start with '/'. This will be added for you, but it should be corrected.

The warning is not relevant to the problem. JSF has already fixed it for you, but it is telling you that you should fix it yourself in the faces-config.xml.

java.lang.ClassNotFoundException: javax.el.ELResolver

This is however pretty serious. This can have several causes:

You are actually not running Tomcat 7.0 at all, but Tomcat 5.5 which is missing this class. Doublecheck it.
You have dropped a bunch of servletcontainer specific libraries such as el-api.jar, jsp-api.jar, etc of a different servletcontainer make/version (perhaps Tomcat 5.5?) in webapp's WEB-INF/lib or in Java's JRE/lib folder. Probably to overcome compilation problems. Moving/copying servletcontainer specific JARs around is the wrong solution. Undo it and remove them all.

Your web.xml is not declared conform at least the Servlet 2.5 specification. Since you mention to be using Tomcat 7.0, which is a Servlet 3.0 container, you should be declaring the web.xml conform Servlet 3.0:

<?xml version="1.0" encoding="UTF-8"?>
<web-app 
    xmlns="http://java.sun.com/xml/ns/javaee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
    id="WebApp_ID" version="3.0">

    <!-- Your config here -->
</web-app>

Update: oh wait ... I googled on the "SimpleHelloByEnteringName" and I discovered that this is actually a Roseindia.net (shudder) example as presented here: Downloading and Installing "SimpleHelloByEnteringName" JSF Example. I would like to stress that this site is the worst Java EE learning resource on the interwebs. I strongly recommend to head to other resources.