我看到了大多数类似的问题，并尝试了大多数解决方案，但是没有任何效果对我有用！
我对Java EE完全陌生，这是我的第一个servlet。
这是我的servlet，它位于：C:\tomcat\webapps\jspbook\WEB-INF\classes
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorld extends HttpServlet {
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title> hello World Title </title>");
out.println("</head>");
out.println("<body>");
out.println("<h1> Hello To World in body!</h1>");
out.println("</body>");
out.println("</html>");
}
}
这是
web.xml中的C:\tomcat\webapps\jspbook\WEB-INF文件 <servlet>
<servlet-name>HelloWorld</servlet-name>
<servlet-class>HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorld</servlet-name>
<url-pattern>/HelloWorld</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file> welcome.html </welcome-file>
</welcome-file-list>
</web-app>
现在，当我重新启动tomcat并尝试
http://127.0.0.1:8080/jspbook/HelloWorld第一次，这是我的第一个错误：
type Exception report
message Error instantiating servlet class HelloWorld
description The server encountered an internal error that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Error instantiating servlet class HelloWorld
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2462)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2451)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Thread.java:722)
root cause
java.lang.ClassNotFoundException: HelloWorld
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2462)
org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2451)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Thread.java:722)
当我重新加载页面时，这是我的第二个错误：
HTTP Status 404 -
type Status report
message
description The requested resource is not available.
我的代码有什么问题？
更新：
我创建一个包并将其命名为
com.jspbook并将其放在此处C:\tomcat\webapps\jspbook\WEB-INF\classes\com\jspbook\HelloWorld.javapackage com.jspbook;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class HelloWorld extends HttpServlet {
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html>");
out.println("<head>");
out.println("<title> hello World Title </title>");
out.println("</head>");
out.println("<body>");
out.println("<h1> Hello To World in body! </h1>");
out.println("</body>");
out.println("</html>");
}
}
web.xml在这里：C:\tomcat\webapps\jspbook\WEB-INF\web.xml<web-app xmlns="http://java.sun.com/xml/ns/j2ee" version="2.4">
<servlet>
<servlet-name>HelloWorld</servlet-name>
<servlet-class>com.jspbook.HelloWorld</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorld</servlet-name>
<url-pattern>/HelloWorld</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file> welcome.html </welcome-file>
</welcome-file-list>
</web-app>
我尝试
http://127.0.0.1:8080/jspbook/HelloWorld，但出现相同的错误！（根本没有编译的类文件）
最佳答案
请将servlet放在一个包中。容器无法从默认包中加载类。