Java Servlet，在创建对DriverManager.getConnection（“ ....”）的引用时给出异常

Question

我正在使用NetBeans 8.1 IDE，Apache Tomcat版本8.0.27和MySQL作为数据库。 端口号和数据库名称正确。但它不起作用。 此后不起作用 Connection cn = DriverManager.getConnection（“ jdbc：mysql：// localhost：.......”，“ root”，“ password”）; 网页屏幕快照已链接。

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


public class CheckSignUp extends HttpServlet {

public void doPost(HttpServletRequest req,HttpServletResponse res) throws ServletException, IOException{
    PrintWriter pw=res.getWriter();
    String name=req.getParameter("name");
    String pass=req.getParameter("pass");
    pw.write("<h1>Welcome</h1>");
    try{
        pw.write("<br><p>Please wait Creating Connection....<p>");
        String sql="INSERT INTO user_demo VALUES(?,?);";
        pw.write("<br><p>Created command is: <p>"+sql);
         DriverManager.registerDriver(new com.mysql.jdbc.Driver());
        pw.write("<p>Driver Loaded</p>");

  Connection cn=DriverManager.getConnection("jdbc:mysql://localhost:3306/demo","root","root");


        pw.write("<p>Connection Created</p>");[enter image description here][1]
        PreparedStatement ps=cn.prepareStatement(sql);
        pw.write("<p>Statement Created</p>");
        ps.setString(1,name);
        ps.setString(2, pass);
        ps.executeUpdate();
        cn.close();
        pw.write("<br><p>New user added Sucessfully<p>");
    }
    catch(Exception ex){
        pw.write("<br><p>Exception Occured: "+ex.getMessage());
    }
}

}

Web browser screen shot