使用ServletContextlistener的ClassNotFoundException [英] ClassNotFoundException with ServletContextlistener

问题描述

每当我尝试从 we.XML 获取上下文参数到 ServletContextListener 类时，我都会遇到异常，我是真的很难理解为什么它不起作用，
这是Apache Tomcat 7.0.11日志中的例外：

I get an exception whenever I try getting context parameter from we.XML into a ServletContextListener class, I am really having hard times understanding why It is not working, here's the exception in Apache Tomcat 7.0.11 log :

 Oct 21, 2011 1:24:23 PM org.apache.catalina.core.StandardContext listenerStart
SEVERE: Error configuring application listener of class alaa.ServletContextListener
java.lang.ClassNotFoundException: alaa.ServletContextListener
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1676)
at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1521)
at   
   org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:415)
at      

at    org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:118)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4618)
at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5184)
at org.apache.catalina.core.StandardContext$1.call(StandardContext.java:5179)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)

这是我网络的一部分.xml：

Here's a part of my web.xml :

 <context-param>
    <param-name>catName</param-name>
    <param-value>meshmesh</param-value>
</context-param>
<context-param>
    <param-name>catBreed</param-name>
    <param-value>egyptian</param-value>
</context-param>  
<listener>
   <listener-class>alaa.CatLisenter</listener-class>
</listener>
<session-config>
      <session-timeout>
        30
      </session-timeout>
</session-config>

这是我的ServletContextListener.java：

Here's my ServletContextListener.java:

package alaa;
import javax.servlet.ServletContext;
import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
public class CatLisenter implements ServletContextListener {

@Override
public void contextInitialized(ServletContextEvent sce) {
    ServletContext sc = sce.getServletContext();
    String name = sc.getInitParameter("catName");

    String breed = sc.getInitParameter("catBreed");

    Cat maCat = new Cat();
    maCat.setName(name);
    maCat.setBreed(breed);

    sc.setAttribute("cat", maCat);
}

@Override
public void contextDestroyed(ServletContextEvent sce) {
    throw new UnsupportedOperationException("Not supported yet.");
}   
}



Here's Cat.java : 





package alaa;

public class Cat {
private String name;
private String breed;


public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

public String getBreed() {
    return breed;
}


public void setBreed(String breed) {
    this.breed = breed;
}
 }

many thanks 

推荐答案

尝试清除tomcat工作目录并清理。之后，发布您的项目并再次运行。

Try to clear the tomcat work directory and clean. After that, publish your project and run again.

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