我收到 404 错误，不知道我错过了什么

Question

我有以下 servlet：

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class MailServlet extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        String m = request.getParameter("mail");
        String sub = request.getParameter("subject");
        String messg = request.getParameter("message");

        SendMail.send(m, sub, messg);
        out.print("Your Mail has been sent successfully");
        out.close();
    }
}

我正在尝试通过以下形式调用它：

<html>
<head>
    <title></title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <meta name="viewport" content="width=device-width">
</head>
<body bgcolor="pink">
    <form action="MailServlet">
        <table>
            <tr>
                <td>To:</td>
                <td><input type="text" name="mail"/><br/></td>
            </tr>
            <tr>
                <td>Subject:</td>
                <td><input type="text" name="subject"><br/></td>
            </tr>
            <tr>
                <td>Message Text:</td>
                <td><textarea rows="12" cols="80" name="message"></textarea><br/></td>
            </tr>
            <tr>
                <td><input type="submit" value="Send"></td>
                <td><input type="reset" value="Reset"></td>
            </tr> 
        </table>
    </form>
</body>

但是，它 returns HTTP 状态 404:

Answer 1

Servlet 需要映射才能访问它们。

如果你使用的是Servlet 3.0，你可以使用：

@WebServlet("/MailServlet") // /MailServlet is the partial URL of the servlet.
public class MailServlet extends HttpServlet {

    [...]

}

如果您不使用 Servlet 3.0，则必须通过将这些行放在 webapp 元素内来映射 web.xml 中的 servlet：

<servlet>
    <servlet-name>MailServlet</servlet-name>
    <servlet-class>com.yourpackage.MailServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>MailServlet</servlet-name>
    <url-pattern>/MailServlet</url-pattern>
</servlet-mapping>

Creating and configuring servlets

我收到 404 错误，不知道我错过了什么

I'm getting a 404 error, don't know what I'm missing

servlets

http-status-code-404