url-pattern Servlet Tomcat 7.0

我正在自学JSP/Servlet。我面临着一个我能解决的问题。我正在创建一个请求servlet的简单表单。问题是，当我将web.xml中的url模式更改为我想要的url时，Tomcat会给我一个404错误。但是，当我将url模式更改为与servlet相同的名称时，它就可以工作了。我注意到的另一件事是，当我手动输入我想要的URL模式时，它可以工作。看来我没有被引导到正确的地方。我已经检查了很多次web.xml，我找不到任何错误。下面是servlet代码:

package email;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import business.User;
import data.UserIO;
/**
 * @author Joel Murach
 */
public class AddToEmailListServlet extends HttpServlet
{    
    int globalCount;
    public void init() throws ServletException{
        globalCount = 0;
    }
    protected void doPost(
        HttpServletRequest request, 
        HttpServletResponse response) 
        throws ServletException, IOException
    {
        //Global variable
        globalCount++;
        // get parameters from the request
        String firstName = request.getParameter("firstName");
        String lastName = request.getParameter("lastName");
        String emailAddress = request.getParameter("emailAddress");
        // get a relative file name
        ServletContext sc = getServletContext();
        String path = sc.getRealPath("/WEB-INF/EmailList.txt");
        // use regular Java objects to write the data to a file
        User user = new User(firstName, lastName, emailAddress);
        UserIO.add(user, path);
        // send response to browser
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();        
        out.println(
          "<!doctype html public "-//W3C//DTD HTML 4.0 Transitional//EN">n"
        + "<html>n"
        + "<head>n"
        + "  <title>Murach's Java Servlets and JSP</title>n"
        + "</head>n"
        + "<body>n"
        + "<h1>Thanks for joining our email list</h1>n"
        + "<p>Here is the information that you entered:</p>n"
        + "  <table cellspacing="5" cellpadding="5" border="1">n"
        + "  <tr><td align="right">First name:</td>n"
        + "      <td>" + firstName + "</td>n"
        + "  </tr>n"
        + "  <tr><td align="right">Last name:</td>n"
        + "      <td>" + lastName + "</td>n"
        + "  </tr>n"
        + "  <tr><td align="right">Email address:</td>n"
        + "      <td>" + emailAddress + "</td>n"
        + "  </tr>n"
        + "  </table>n"
        + "<p>To enter another email address, click on the Back <br>n"
        + "button in your browser or the Return button shown <br>n"
        + "below.</p>n"
        + "<form action="join_email_list.html" "
        + "      method="post">n"
        + "  <input type="submit" value="Return">n"
        + "</form>n"
        + "<p>This page has been accessed "
        + globalCount + " times.</p>"
        + "</body>n"
        + "</html>n");
        System.out.println(globalCount);
        log("Global variable" +globalCount);
        out.close();
    }    
    protected void doGet(
        HttpServletRequest request, 
        HttpServletResponse response) 
        throws ServletException, IOException
    {
        doPost(request, response);
    }
}

这里是web.xml文件:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee      http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <!-- the definitions for the servlets -->
    <!-- the mapping for the servlets -->
    <servlet>
        <servlet-name>DisplayMusicChoicesServlet</servlet-name>
        <servlet-class>email.DisplayMusicChoicesServlet</servlet-class>
    </servlet>
    <servlet>
        <servlet-name>AddToEmailListServlet</servlet-name>
        <servlet-class>email.AddToEmailListServlet</servlet-class>
    </servlet>
    <!-- other configuration settings for the application -->
    <servlet-mapping>
        <servlet-name>DisplayMusicChoicesServlet</servlet-name>
        <url-pattern>/displayMusicChoices</url-pattern>
    </servlet-mapping>
    <servlet-mapping>
        <servlet-name>AddToEmailListServlet</servlet-name>
        <url-pattern>/addToEmailList</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>30</session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>join_email_list.html</welcome-file>
    </welcome-file-list>
</web-app>

对你的所作所为有很多批评，但我将仅限于你的问题。

如果将应用程序部署到Tomcat 7/webapps目录下的WAR文件foo中。war，那么调用AddToEmailListServlet并在浏览器中显示该HTML页面的URL将是:

http://host:8080/foo/AddToEmailListServlet

我假设您在表单中张贴这三个请求参数，因为您必须在发送电子邮件地址之前对@符号进行编码。

在"WebContent"目录下创建一个新文件夹，而不是像admin.xhtml那样给出特定的文件url。在这种情况下，假设文件夹名称是"安全的"，将admin.xhtml放在该文件夹中，然后<url-pattern>/secured/*</url-pattern>

为我工作，我希望这对我有帮助

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