Question

我正在尝试简单的servlet和数据库连接程序，但我在运行我的代码并填写表单并提交后我一直面临数据库连接的问题我得到了未知的数据库问题。我一直在寻找合理的网站解决方案，但无法得到任何..

看一下servlet代码，即RegisterServlet.java页面

package com.jwt.servlet;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;

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



 public class RegisterServlet extends HttpServlet {


public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {

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

    String n = request.getParameter("userName");
    String p = request.getParameter("password");
    String e = request.getParameter("email");
    String c = request.getParameter("language");
 try{
 System.out.println("connecting...");

        Class.forName("com.mysql.jdbc.Driver");
        System.out.println("connecting to physical database...");
        Connection con = DriverManager.getConnection(
                "jdbc:mysql://localhost:3306/User1", "root", "root");

        PreparedStatement ps = con.prepareStatement("insert into USERDETAILS values(?,?,?,?)");
        System.out.println("Connection has been made");

        ps.setString(1, n);
        ps.setString(2, p);
        ps.setString(3, e);
        ps.setString(4, c);

        int i = ps.executeUpdate();
        if (i > 0)
            out.print("You are successfully registered...");

    } catch (Exception e2) {
        System.out.println(e2);
    }


    out.close();
}

}

这是register.jsp页面

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
  pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"                                                      "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
<script>
function validateForm() {
var x = document.forms["myForm"]["userName"].value;
var y = document.forms["myForm"]["password"].value;
var z = document.forms["myForm"]["email"].value;
var checkString = document.myForm.userName.value;


if ((x == null || x == "") || (y==null || y=="") || (z==null || z=="" ) )
{
    alert("Enter the mandatory fields");
    return false;
    }
}
</script>
</head>
<body>
<div style="background-color:grey;color:white;padding:25px 75px 25px 50px;          text-align:center; border: 1px solid red; display:inline-block; text-   style:bold">
<form name="myForm" action="register" onsubmit="return validateForm()" method="post">
<p id="tt" style="margin-left"></p>
<script>
 document.getElementById("tt").innerHTML = Date();
</script>
    Name*:<input type="text" name="userName"  placeholder="Enter Name"    style="margin-left:35px; " onkeypress="return alpha(event)" /><br/>
    Password*:<input type="password" name="password" style="margin-     left:12px; margin-top:10px" placeholder="Enter Password" /><br/>
    Email Id*:<input type="text" name="email" placeholder="Enter Email Id" style="margin-left:18px; margin-top:10px" /><br/>
    Language: <select name="language" style="margin-left:80px; margin-top:10px">
      <option>--Select--</option>
        <option>Hindi</option>
        <option>English</option>
        <option>French</option>
    </select> <br/>
    <p id="demo" style="display:none">Saved...</p>
<input type="submit"            onclick="document.getElementById('demo').style.display='block'"  value="Submit"                                       style="margin-left:150px; margin-top:10px"/>
 <footer style="margin-bottom"> By </footer>
</form>
</div>
</body>
</html>

这是web.xml页面

 <?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" version="3.0">
  <display-name>ServletDBExample</display-name>
  <servlet>
    <servlet-name>Register</servlet-name>
    <servlet-class>com.jwt.servlet.RegisterServlet</servlet-class>
</servlet>



<servlet-mapping>
    <servlet-name>Register</servlet-name>
    <url-pattern>/register</url-pattern>
</servlet-mapping>

<welcome-file-list>
    <welcome-file>register.jsp</welcome-file>
</welcome-file-list>
</web-app>

Answer 1

尝试删除用户名＆amp;密码或尝试将其更改为其他用户。它应该工作。我遇到了同样的错误，似乎对我有用。

Answer 2

请确认您输入的MySql用户名和密码是否正确。 User1数据库应该存在于MySql数据库中。别忘了添加mysql-connector.jar文件。

如果可能，请发布您的错误消息。

运行servlet代码时的未知数据库

2 个答案: