Java – Tomcat can’t find my servlet and throw an exception, but why?

I tried to get into Java Web development, but it seems to be running into a strange problem with Tomcat and a very simple servlet Whenever I try to load the application, Catalina logs play:

Caused by: java.lang.IllegalArgumentException: Servlet mapping specifies an unkNown servlet name MyServlet
    at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:2393)
    at org.apache.catalina.core.StandardContext.addServletMapping(StandardContext.java:2373)
    ... 40 more
Mar 4,2009 10:37:58 AM org.apache.catalina.startup.ContextConfig applicationWebConfig
SEVERE: Parse error in application web.xml file at jndi:/localhost/mywebapp/WEB-INF/web.xml
java.lang.IllegalArgumentException: Servlet mapping specifies an unkNown servlet name MyServlet

Decent feeling can't seem to find my servlet However, the servlet seems to be in the right place X-4545 X-4545 X-4545 X- 200 X- 200 X- 200 200 X- 200 200 X-

As a reference, this is the web XML file:

<?xml version="1.0" encoding="ISO-8859-1"?>
<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_2_5.xsd" version="2.5"> 
    <description>My first web app in Java.</description>
    <display-name>My Web App</display-name>

    <servlet>
        <servlet-name>MyServlet</servlet-name>
        <servlet-class>MyServlet</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>MyServlet</servlet-name>
        <url-pattern>/myservlet</url-pattern>
    </servlet-mapping>
</web-app>

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to update

To be absolutely sure it wasn't some kind of tool, I started a new copy of Tomcat and tried again Once you do this, this begins to appear in the log file:

SEVERE: Error deploying web application archive mywebapp.war
java.lang.UnsupportedClassVersionError: Bad version number in .class file (unable to load class MyServlet)

I took mine The class file is dumped to the myservlet class and repackaged with - target 1.5 War, everything is perfect

Thank you very much for your help! A good lesson in troubleshooting won't hurt anyone

Solution

So given the updated information, it seems that your problem is that the compiler you use for your class may be a JDK that runs a newer version of Tomcat

Check the JDK version used to start Tomcat and see if you can do something to reconcile the differences from the version you are using to compile the servlet

This should clear up your problem