javax.servlet.ServletException:实例化servlet类java时出错.UserScores

Question

我一直在研究类似的主题，但没有一个解决方案奏效。我正试图使用Eclipse在Web应用程序中映射一个简单的HttpServlet，但当表单从调用servlet上get的html页面提交时，出现了以下错误。

HTTP Status 500 - Error instantiating servlet class java.UserScoresServlet
type Exception report
message Error instantiating servlet class java.UserScoresServlet
description The server encountered an internal error that prevented it from fulfilling this request.
exception
javax.servlet.ServletException: Error instantiating servlet class java.UserScoresServlet
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
java.lang.Thread.run(Thread.java:748)
root cause
java.lang.ClassNotFoundException: java.UserScoresServlet
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1714)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
java.lang.Thread.run(Thread.java:748)
note The full stack trace of the root cause is available in the Apache Tomcat/7.0.34 logs.

我尝试过使用@WebServlet注释和Web.xml文件进行映射，但都没有成功。我试着使用其中一个，而不是同时使用两者。当使用JSP和HTML页面时，我的映射工作正常。我的XML文件映射如下，位于WEB-INF目录中。

<display-name>GetUserScores</display-name>
<servlet>
<servlet-name>GetUserScores</servlet-name>
<servlet-class>java.UserScoresServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>GetUserScores</servlet-name>
<url-pattern>/GetUserScores</url-pattern>
</servlet-mapping>
</web-app>

服务器类如下所示。如上所述，我一直在做注释或web.xml，而不是两者都做。两者都抛出相同的异常。

package java;
import java.io.IOException;
import java.score.jpa.Score;
import java.score.jpa.ScoreService;
import java.user.jpa.User;
import java.user.jpa.UserService;
import java.util.List;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class UserScoresServlet
*/
@WebServlet(name = "GetUserScores", urlPatterns = "/GetUserScores")
public class UserScoresServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
private UserService userService;
private ScoreService scoreService;
/**
* @see HttpServlet#HttpServlet()
*/
public UserScoresServlet() {
super();
userService = new UserService();
scoreService = new ScoreService();
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String firstName = (String)request.getParameter("firstName");
String lastName = (String)request.getParameter("firstName");
User user = userService.findUserByFirstAndLastName(firstName, lastName);
if (user != null){
List<Score> scoreList = scoreService.findAllScoresByUser(user);
request.setAttribute("scoreList", scoreList);
}
gotoPage("/scores", request, response);
}
private void gotoPage(String address, HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(address);
dispatcher.forward(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
}
}

文件结构见图：文件结构图像

任何人能提供的任何帮助都将是巨大的帮助。我已经彻底搜索了这个网站，并尝试了每一个类似问题的建议，但都无济于事。感谢您的帮助。

Answer 1

如JLS中所述，不应使用java作为开发包的名称：

仅用于本地使用的包的名称应具有以小写字母开头的第一个标识符，但该第一个标识符不应是标识符java；以标识符java开头的包名称是为Java SE平台的包保留的

在代码中注明：

package java;
import java.io.IOException;
import java.score.jpa.Score;
import java.score.jpa.ScoreService;
import java.user.jpa.User;
import java.user.jpa.UserService;
import java.util.List;
//rest of code...

将包的名称更改为其他名称。