我正在尝试实例化我的servlet，但我得到这个500状态错误。我读了其他的帖子，但没有一个建议的解决方案似乎适用于我的错误。
My SampServlet Class
package com.example;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet(name = "SampServlet", value = "/SampServlet")
public class SampServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doPost(request, response);
}
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//define that we want to send HTML to our browser
response.setContentType("text/html");
// create our PrintWriter that allows us to write out text as well as write HTML to the screen
PrintWriter out = response.getWriter();
try {
out.println("<h3>Testing Servlets</h3>");
}
finally {
out.close();
}
}
}
我的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_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>SampServlet</servlet-name>
<servlet-class>com.example.SampServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>SampServlet</servlet-name>
<url-pattern>/SampServlet</url-pattern>
</servlet-mapping>
</web-app>
项目结构输入图片描述
当我转到http://localhost:8080/SampServlet
时得到的错误Message Error instantiating servlet class [com.example.SampServlet]
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
jakarta.servlet.ServletException: Error instantiating servlet class [com.example.SampServlet]
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:356)
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399)
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:867)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1716)
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.base/java.lang.Thread.run(Thread.java:833)
Root Cause
java.lang.NoClassDefFoundError: javax/servlet/http/HttpServlet
java.base/java.lang.ClassLoader.defineClass1(Native Method)
java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1013)
java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150)
org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2527)
org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:877)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1413)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1257)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:356)
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399)
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:867)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1716)
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.base/java.lang.Thread.run(Thread.java:833)
Root Cause
java.lang.ClassNotFoundException: javax.servlet.http.HttpServlet
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1449)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1257)
java.base/java.lang.ClassLoader.defineClass1(Native Method)
java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1013)
java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150)
org.apache.catalina.loader.WebappClassLoaderBase.findClassInternal(WebappClassLoaderBase.java:2527)
org.apache.catalina.loader.WebappClassLoaderBase.findClass(WebappClassLoaderBase.java:877)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1413)
org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1257)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:690)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:356)
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399)
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:867)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1716)
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.base/java.lang.Thread.run(Thread.java:833)
Note The full stack trace of the root cause is available in the server logs.
Tomcat 10.0及以上版本使用新的Jakarta EE包作为代码。这意味着，例如，javax.servlet.http.HttpServlet现在是jakarta.servlet.http.HttpServlet。由于Oracle和他们对开发社区的敌意，这一变化始于EE规范的第9版。
你的代码应该这样开始:
import jakarta.servlet.*;
import jakarta.servlet.http.*;
import jakarta.servlet.annotation.*;
import java.io.IOException;
import java.io.PrintWriter;
@WebServlet(name = "SampServlet", value = "/SampServlet")
public class SampServlet extends HttpServlet {
使用新的规格。Tomcat还有一个开源工具，可以将更大的代码库从EE 8转换为EE 9规范。