jakarta.servlet.ServletException:类[com.practice.MyServlet]不是Servlet [英] jakarta.servlet.ServletException: Class [com.practice.MyServlet] is not a Servlet
问题描述
我是使用servlet的初学者.
我正在创建一个servlet，但是运行后却出现错误
谁能帮我解决这个问题.
错误
I am beginner to working with servlet.
I am creating a servlet and but after running that i am getting error
Can anyone help me to resolve this.
Error
类型异常报告
消息类[com.practice.MyServlet]不是Servlet
说明服务器遇到意外状况，该状况是阻止了该请求的执行.
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
例外
jakarta.servlet.ServletException:类[com.practice.MyServlet]是不是Servlet org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:682)org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:332)org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)org.apache.coyote.AbstractProtocol $ ConnectionHandler.process(AbstractProtocol.java:859)org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun(NioEndpoint.java:1568)org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)java.util.concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:624)org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run(TaskThread.java:61)java.lang.Thread.run(Thread.java:748)根本原因
jakarta.servlet.ServletException: Class [com.practice.MyServlet] is not a Servlet org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:682) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:332) org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:859) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1568) org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Thread.java:748) Root Cause
java.lang.ClassCastException:com.practice.MyServlet无法强制转换为jakarta.servlet.Servlet org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543)org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:682)org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:332)org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374)org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)org.apache.coyote.AbstractProtocol $ ConnectionHandler.process(AbstractProtocol.java:859)org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun(NioEndpoint.java:1568)org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)java.util.concurrent.ThreadPoolExecutor $ Worker.run(ThreadPoolExecutor.java:624)org.apache.tomcat.util.threads.TaskThread $ WrappingRunnable.run(TaskThread.java:61)java.lang.Thread.run(Thread.java:748)注意根本原因可在服务器日志中找到.
java.lang.ClassCastException: com.practice.MyServlet cannot be cast to jakarta.servlet.Servlet org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:543) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:682) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:332) org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:374) org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:859) org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1568) org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) java.lang.Thread.run(Thread.java:748) Note The full stack trace of the root cause is available in the server logs.
单击此处查看项目目录
MyServlet.java
package com.practice;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.*;
import javax.servlet.http.*;
/**
*
* @author admin
*/
public class MyServlet extends HttpServlet {
@Override
public void doGet(HttpServletRequest request,HttpServletResponse response)throws ServletException, IOException
{
PrintWriter out=response.getWriter();
response.setContentType("test/html");
out.print("<h1>This is get method of my servlet</h1>");
}
}
Web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
version="3.1">
<servlet>
<servlet-name>myservlet</servlet-name>
<servlet-class>com.practice.MyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>myservlet</servlet-name>
<url-pattern>/myservlet</url-pattern>
</servlet-mapping>
<session-config>
<session-timeout>
30
</session-timeout>
</session-config>
</web-app>
推荐答案
您基本上是在WAR中实际包括特定于Tomcat 9.x(Servlet 4.0)的JAR文件，然后针对Tomcat 9.x(Servlet 4.0)编写/编译代码)或更高版本，然后将WAR部署到Tomcat 10.x(Servlet 5.0)或更高版本.这根本不是正确的方法.
You're basically physically including Tomcat 9.x (Servlet 4.0) specific JAR file in WAR and then writing/compiling code against Tomcat 9.x (Servlet 4.0) or older and then then deploying the WAR to Tomcat 10.x (Servlet 5.0) or newer. This is not the correct approach at all.
从Tomcat 10.x(Servlet 5.0)开始， javax.* 软件包已重命名为 jakarta.* 软件包.
Since Tomcat 10.x (Servlet 5.0) the javax.* package has been renamed to jakarta.* package.
换句话说，请确保不要在WAR中随机放置其他服务器的JAR文件，例如 tomcat-servlet-api-9.0.4.jar .这只会造成麻烦.完全将其删除，然后从
In other words, please make sure that you don't randomly put JAR files of a different server in your WAR such as tomcat-servlet-api-9.0.4.jar. This will only cause trouble. Remove it altogether and edit the imports of your servlet class from
import javax.servlet.*;
import javax.servlet.http.*;
到
import jakarta.servlet.*;
import jakarta.servlet.http.*;
与此同时，还请确保声明 web.xml 的根元素符合目标服务器的Servlet API版本，在Tomcat 10.x的情况下，因此是Servlet5.0(因此与Tomcat 8.0基本匹配的 not Servlet 3.1).
While at it, please also make sure that the root element of the web.xml is declared conform the Servlet API version of the target server, which is in case of Tomcat 10.x thus Servlet 5.0 (and thus not Servlet 3.1 which basically matches Tomcat 8.0).
<web-app
xmlns="https://jakarta.ee/xml/ns/jakartaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="https://jakarta.ee/xml/ns/jakartaee https://jakarta.ee/xml/ns/jakartaee/web-app_5_0.xsd"
version="5.0"
>
<!-- Config here. -->
</web-app>
另请参见:
- Tomcat版本
- Tomcat 9将servlet强制转换为javax.servlet.Servlet而不是jakarta.servlet.http.HttpServlet
这篇关于jakarta.servlet.ServletException:类[com.practice.MyServlet]不是Servlet的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
