HTTP状态500 –内部服务器错误（Java，Eclipse，Servlet，Tomcat）

Question

我跟踪了Java的Servlet教程，一遍又一遍地发现了相同的问题。我可以在Tomcat 8.5.47中提供一个页面，但是，例如，当我尝试将Servlet绑定到表单动作中时，执行该消息时会出现以下错误：消息错误，实例化Servlet类[xxx.xxx.SearchServlet]

这是一个“动态Web项目”。我检查了项目属性，并且Source src部分指向Deploy Path WEB-INF / classes。另外，所有目录都包含在“构建路径”中。

以下是主要文件：

src / xxx.xxx / SearchServlet.java

package xxx.xxx;

import java.io.IOException;
import java.io.PrintWriter;

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

public class SearchServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public void service(HttpServletRequest req, HttpServletResponse res) throws IOException {

        String str = req.getParameter("str_search");

        PrintWriter out = res.getWriter();

        out.println(str);

    }

}

WebContent / WEB-INF / web.xml

<?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>search</servlet-name>
        <servlet-class>SearchServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>search</servlet-name>
        <url-pattern>/search</url-pattern>
    </servlet-mapping>
</web-app>

这是完整的报告：

HTTP状态500 –内部服务器错误类型异常报告实例化servlet类[SearchServlet]时发生消息错误描述服务器遇到意外情况，阻止其满足请求。例外javax.servlet.ServletException：实例化servlet类[SearchServlet]时出错org.apache.catalina.authenticator.AuthenticatorBase.invoke（AuthenticatorBase.java:528）org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:81）org.apache.catalina.valves.AbstractAccessLogValve.invoke（AbstractAccessLogValve.java:678）org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:343）org.apache.coyote.http11.Http11Processor.service（Http11Processor.java:798）org.apache.coyote.AbstractProcessorLight.process（AbstractProcessorLight.java:66）org.apache.coyote.AbstractProtocol $ ConnectionHandler.process（AbstractProtocol.java:810）org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java:1500）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java.lang.ClassNotFoundException：SearchServletorg.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1360）org.apache.catalina.loader.WebappClassLoaderBase.loadClass（WebappClassLoaderBase.java:1182）org.apache.catalina.authenticator.AuthenticatorBase.invoke（AuthenticatorBase.java:528）org.apache.catalina.valves.ErrorReportValve.invoke（ErrorReportValve.java:81）org.apache.catalina.valves.AbstractAccessLogValve.invoke（AbstractAccessLogValve.java:678）org.apache.catalina.connector.CoyoteAdapter.service（CoyoteAdapter.java:343）org.apache.coyote.http11.Http11Processor.service（Http11Processor.java:798）org.apache.coyote.AbstractProcessorLight.process（AbstractProcessorLight.java:66）org.apache.coyote.AbstractProtocol $ ConnectionHandler.process（AbstractProtocol.java:810）org.apache.tomcat.util.net.NioEndpoint $ SocketProcessor.doRun（NioEndpoint.java:1500）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）注意在服务器日志中可以找到根本原因的完整堆栈跟踪。Apache Tomcat / 8.5.47

我想知道这是否与Eclipse Installation的权限有关，或者是否与项目结构有关？有人有小费吗？也许我应该寻找一个容器映像或尝试在其上构建的东西？谢谢。

Answer 1

只需在<servlet-class>标记中添加类的完全限定名称。

示例：

<servlet-class>com.stack.SearchServlet</servlet-class>

或者，如果您愿意：

package com.stack;    

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;    

/**
 * Servlet implementation class MyServlet
 */
@WebServlet("/MyServlet")
public class MyServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public MyServlet() {
        super();
        // TODO Auto-generated constructor stub
    }    

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        response.getWriter().append("Served at: ").append(request.getContextPath());
    }    

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }    

}