未找到 Java servlet 资源答案

【问题标题】：Java servlets resource not found未找到 Java servlet 资源
【发布时间】：2014-09-02 16:58:55
【问题描述】：

我正在尝试使用 servlet 将新用户输入到我的数据库中。当我单击注册表单中的提交按钮时出现问题。我得到“请求的资源不可用。”错误。我想不通。

你们能帮帮我吗？

register.jsp

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>Sign Up</title>
</head>
<body>
    <h1>Enter your information</h1>
    <form method = "POST" action="RegisterServlet">
        Username <br/>
        <input type="text" name="username"/><br/>
        Password <br/>
        <input type="password" name="password"/><br/>
        Email <br/>
        <input type="text" name="email"/><br/>
        First name <br/>
        <input type="text" name="fname"/><br/>
        Last name <br/>
        <input type="text" name="lname"/><br/>
        <input type="submit" value="Confirm" />
    </form>
</body>

RegisterServlet doPost() 方法

    package servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;
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(name = "RegisterServlet", urlPatterns = {"/RegisterServlet"})
public class RegisterServlet extends HttpServlet {

    /**
     * Processes requests for both HTTP <code>GET</code> and <code>POST</code>
     * methods.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();

        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String email = request.getParameter("email");
        String fname = request.getParameter("fname");
        String lname = request.getParameter("lname");
        String admin = "no";

        try {
            Class.forName("com.mysql.jdbc.Driver").newInstance();
            Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/mobmelbaza", "root", "");

            String query = "insert into korisnici(user, pass, email, ime, prezime, admin)"
                    + "values ('" + username + "','" + password + "','" + email + "','" + fname + "','" + lname + "', '" + admin + "')";

            Statement st = con.createStatement();

            boolean done = st.execute(query);

            if (done == true) {
                out.print("Sign Up sucessfull");
            } else {
                out.print("Failed");
            }

        } catch (Exception ex) {
            ex.printStackTrace();
        }

    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}

web.xml

    <?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.1" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd">
    <servlet>
        <servlet-name>RegisterServlet</servlet-name>
        <servlet-class>servlet.RegisterServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>RegisterServlet</servlet-name>
        <url-pattern>/RegisterServlet</url-pattern>
    </servlet-mapping>
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
</web-app>

【问题讨论】：

如果您不使用 servlet 注释，请发布您的完整 web.xml
我将发布应该更好的完整 RegisterServlet 代码。我正在使用注释。
您的register.jsp 放在哪里？如果它的 URL 看起来像 http://server/yourApp/foo/register.jsp，那么您的 <form ...> 中的 action="RegisterServlet" 将注册为 http://server/yourApp/foo/RegisterServlet 而不是 http://server/yourApp/RegisterServlet。还有你用的是什么服务器？

标签： java xml jsp servlets

【解决方案1】：

正如您所说，您使用注释更好地从 web.xml 中删除映射您可以使用基于注释的映射，例如

@WebServlet(name = "RegisterServlet", urlPatterns = {"/RegisterServlet"})

或

<servlet>
    <servlet-name>RegisterServlet</servlet-name>
    <servlet-class>servlet.RegisterServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>RegisterServlet</servlet-name>
    <url-pattern>/RegisterServlet</url-pattern>
</servlet-mapping>

你不能同时拥有两个

【讨论】：

“你不能同时拥有两者”它可能取决于平台。我刚刚在 Tomcat v8.0 上测试了这个配置，它运行良好。
非常感谢！有效。我删除了注释