HTTP状态500 - 实例化servlet类example.webApp时出错

Question

我创建了简单的servlet并将其部署到tomcat服务器但是我收到以下错误：Objective-C 截图：

webApp.java：

HTTP Status 500 - Error instantiating servlet class example.webApp

web.xml：

package example;

import java.io.IOException;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class webApp extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) 
            throws ServletException, IOException {
        resp.getWriter().println("Testing tomcat") ;
    }
}

当我将<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1"> <servlet> <servlet-name>Test</servlet-name> <servlet-class>example.webApp</servlet-class> </servlet> <servlet-mapping> <servlet-name>Test</servlet-name> <url-pattern>/test</url-pattern> </servlet-mapping> <display-name>test</display-name> <welcome-file-list> <welcome-file>index.html</welcome-file> <welcome-file>index.htm</welcome-file> <welcome-file>index.jsp</welcome-file> <welcome-file>default.html</welcome-file> <welcome-file>default.htm</welcome-file> <welcome-file>default.jsp</welcome-file> </welcome-file-list> </web-app> 写入Eclipse浏览器时，我得到了上面的内容。如果我再次输入localhost:8080/test/test，我会收到此错误：http://i.hizliresim.com/YBYE4z.png

我很困惑。你能帮助我吗？怎么了？ 很抱歉提供图片链接，因为我无法直接更新到此网站。

第一张图片的文字是：

输入例外报告

message错误实例化servlet类example.webApp

说明服务器遇到内部错误，导致无法完成此请求。

例外

localhost:8080/test/test

注意javax.servlet.ServletException: Error instantiating servlet class example.webApp org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1527) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1484) java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Unknown Source) root cause java.lang.ClassNotFoundException: example.webApp org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1313) org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1164) org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:617) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518) org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091) org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1527) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1484) java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Unknown Source) 日志中提供了根本原因的完整堆栈跟踪。

Answer 1

有时，在创建servlet时，可能无法在build文件夹中生成类文件。我们应该清理项目然后构建。它对我有用。 https://stackoverflow.com/a/11611477/2294855

Answer 2

尝试清理项目并运行。 如果您正在使用eclipse 项目 - ＆gt;清洁

对于NetBeans，请尝试运行 - ＆gt;清理和建造项目

Answer 3

我认为你应该写在你的web.xml中 <servlet-class>example.webApp.Test</servlet-class>代替<servlet-class>example.webApp</servlet-class>