java Tomcat Servlet ClassNotFoundException

Tomcat Servlet ClassNotFoundException

提问by BILL

I created simple servlet.

我创建了简单的 servlet。

package servlets;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;

public class testServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        out.print("TEST");
        out.close();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

web.xml configuration

web.xml 配置

<servlet>
       <servlet-name>testServlet</servlet-name>
       <servlet-class>servlets.testServlet</servlet-class>
       <load-on-startup>3</load-on-startup>
   </servlet>
    <servlet-mapping>
        <servlet-name>testServlet</servlet-name>
        <url-pattern>/test</url-pattern>
    </servlet-mapping>

startup log

启动日志

cmd /c ""D:\Program Files\Java\jdk1.6.0_24\bin\java" -Dcatalina.base=C:\Users\Administrator\.IntelliJIdea10\system\tomcat\_WebApplication "-Dcatalina.home=D:\Program Files\Apache Software Foundation\Tomcat 7.0" "-Djava.io.tmpdir=D:\Program Files\Apache Software Foundation\Tomcat 7.0\temp" -cp "D:\Program Files\Apache Software Foundation\Tomcat 7.0\bin\bootstrap.jar;D:\Program Files\Apache Software Foundation\Tomcat 7.0\bin\tomcat-juli.jar" org.apache.catalina.startup.Bootstrap start"
13 кв?т 2011 23:35:47 org.apache.catalina.core.AprLifecycleListener init
INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: D:\Program Files\Java\jdk1.6.0_24\bin;.;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;D:\Program Files\JetBrains\IntelliJ IDEA 10.0.2\bin\..\.\bin;C:\Program Files\Haskell\bin;D:\Program Files\Haskell Platform11.2.0.0\lib\extralibs\bin;D:\Program Files\Haskell Platform11.2.0.0\bin;C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v3.2\bin\;C:\Program Files\NVIDIA Corporation\PhysX\Common;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Microsoft SQL Server0\Tools\Binn\;C:\Program Files\Microsoft SQL Server0\DTS\Binn\;D:\Program Files\TortoiseSVN\bin;D:\Program Files\Microsoft Network Monitor 3\;D:\Program Files\MySQL\MySQL Server 5.5\bin;C:\Users\Administrator\AppData\Roaming\cabal\bin;d:\program files\jetbrains\intellij idea 10.0.2\jre\jre\bin
13 кв?т 2011 23:35:48 org.apache.coyote.AbstractProtocolHandler init
INFO: Initializing ProtocolHandler ["http-bio-8080"]
13 кв?т 2011 23:35:48 org.apache.coyote.AbstractProtocolHandler init
INFO: Initializing ProtocolHandler ["ajp-bio-8009"]
13 кв?т 2011 23:35:48 org.apache.catalina.startup.Catalina load
INFO: Initialization processed in 565 ms
13 кв?т 2011 23:35:48 org.apache.catalina.core.StandardService startInternal
INFO: Starting service Catalina
13 кв?т 2011 23:35:48 org.apache.catalina.core.StandardEngine startInternal
INFO: Starting Servlet Engine: Apache Tomcat/7.0.12
13 кв?т 2011 23:35:48 org.apache.catalina.startup.HostConfig deployDescriptor
INFO: Deploying configuration descriptor ROOT.xml from C:\Users\Administrator\.IntelliJIdea10\system\tomcat\_WebApplication\conf\Catalina\localhost
13 кв?т 2011 23:35:48 org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet testServlet as unavailable
13 кв?т 2011 23:35:48 org.apache.catalina.core.StandardContext loadOnStartup
SEVERE: Servlet  threw load() exception
java.lang.**ClassNotFoundException: servlets.testServlet**
    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 org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:397)
    at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:118)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1062)
    at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1010)
    at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4935)
    at org.apache.catalina.core.StandardContext.call(StandardContext.java:5262)
    at org.apache.catalina.core.StandardContext.call(StandardContext.java:5257)
    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)

Why is there a mistake?

为什么会有错误？

回答by Bozho

You must have this file:

你必须有这个文件：

webapps/WEB-INF/classes/servlets/testServlet.class

webapps/WEB-INF/classes/servlets/testServlet.class

That said, please name your classes with pascal case instead of camel case - TestServlet

也就是说，请用 pascal case 而不是驼峰命名你的类 - TestServlet

回答by user3150293

1. Every time you create or edit an existing servlet, you should export the .war file back to WebApps folder.
2. Make sure the servlet classes created need not be under /WEB-INF/CLASSES, but should be created under a package.
3. Make sure the .jsp file which is using this servlet class is being referenced in xxxx.jsp in web.xml file.

1. 每次创建或编辑现有 servlet 时，都应该将 .war 文件导出回 WebApps 文件夹。
2. 确保创建的 servlet 类不需要在 /WEB-INF/CLASSES 下，而应该在包下创建。
3. 确保在 web.xml 文件中的 xxxx.jsp 中引用了使用此 servlet 类的 .jsp 文件。