使用Eclipse创建Servlet后，Tomcat 7服务器无法启动

问题描述

尝试在Eclipse中启动本地Tomcat 7服务器时出现错误:

There error I get when I attempt to start the local Tomcat 7 server in Eclipse:

这些是我采取的步骤:

1. 创建一个名为"test"的新项目.
2. 创建一个新的index.jsp文件.

3. 创建一个名为"Testservlet"的新 servlet .

包名称:testpackage

Package name: testpackage

这是Eclipse中的路径结构:

This is the path structure in Eclipse:

web.xml 文件的内容:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>test</display-name>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>

  <servlet>
    <servlet-name>Testservlet</servlet-name>
    <servlet-class>testpackage.Testservlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>Testservlet</servlet-name>
    <url-pattern>/Testservlet</url-pattern>
  </servlet-mapping>
</web-app>

Testservlet.java 文件的内容:

Contents of the Testservlet.java file:

package testpackage;

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

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

@WebServlet(description = "a test servlet", urlPatterns = { "/Testservlet" })
public class Testservlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        PrintWriter out = response.getWriter();
        response.setContentType("text/html");
        out.println("This is a test servlet");
    }
}

接下来，我将项目添加到Tomcat服务器并尝试启动服务器.这是我在停止服务器运行时遇到错误的情况.

Next I add the project to the Tomcat server and attempt to start the server. Which is when I get the error stopping the server from running.

如果我从web.xml文件中删除了与servlet相关的标记，则服务器可以正常启动.这是我删除的标记:

If I remove the servlet related markup from the web.xml file the server starts perfectly fine. This is the markup I remove:

 <servlet>
    <servlet-name>Testservlet</servlet-name>
    <servlet-class>testpackage.Testservlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>Testservlet</servlet-name>
    <url-pattern>/Testservlet</url-pattern>
  </servlet-mapping>

我假设我需要在web.xml中使用上面的标记，以便当我导航到test/Testservlet时才能显示servlet?尤其是当我将项目部署到远程服务器时.

I assume that I need the above markup in the web.xml in order for the servlet to display when I navigate to test/Testservlet though? Especially when I deploy the project to a remote server.

我在做什么错了?

推荐答案

Servlet API 3.0包括一个名为 javax.servlet.annotation 的新程序包，它提供了 @WebServlet 之类的注释.用于注释servlet类，这可以消除对 web.xml 中servlet配置的使用.因此， servlet 和 servlet-mapping 已过时.

Servlet API 3.0 included a new package called javax.servlet.annotation which provides annotations like @WebServlet to be used to annotate a servlet class and this can eliminate the use of servlet configuration in web.xml. So, servlet and servlet-mapping are obsolete.

此外，您不应该在应用程序中部署 servlet-api.jar .Tomcat 7已经具有这些类，并且支持许多Servlet API.它将使用您的Web应用程序部署描述符自动选择要加载的servlet API.

Also you should not deploy servlet-api.jar with your application. Tomcat 7 already has these classes and it supports many Servlet APIs. It will automatically choose which servlet API to load using your web application deployment descriptor.

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