Question

我有一个MySQL数据库，我在其中创建了一个用户标识“mads”和密码“mads”。如果用户存在于数据库中，我想通过JSP站点和servlet进行测试。我认为我的代码是正确的，但我一直得到错误的异常...我的用户无效。所以我想我的代码不正确： - / 与我的数据库的连接是成功的。在不知情的情况下，我有一种感觉，我的servlet会查看数据库中的最后一列，而不是第一列？我不知道这与它有什么关系。任何人都能看出它的错误吗？

最诚挚的问候 MADS 我的JSP页面如下所示：

<title>Validation</title>
</head>
<body>
    <br><br><br>
        <center>
            <h1>Please enter user name and password</h1>

            <form name="frm" action="LoginValidation" method="post">
                <input type="text" name="user">
                <input type ="password" name="pass">
                <input type="submit" value="Check">
            </form>
        </center>
</body>

和我的Servlet：

package jsp;

import java.io.*;
//import java.util.*;
import java.sql.*;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import javax.servlet.*;

@WebServlet(urlPatterns = {"/LoginValidation"})
public class Validation extends HttpServlet {

    private static final long serialVersionUID = 1L;
    private ServletConfig config;

    public void init (ServletConfig config) 
    throws ServletException{
        this.config = config;
    }

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


        PrintWriter out = response.getWriter();
        String connectionURL = "jdbc:mysql://localhost/dblogin";
        Connection connection = null;
        ResultSet rs;
        String userid = new String("");
        String password = new String("");

        response.setContentType("text/html");
        try {
            // Load the database driver
            Class.forName("com.mysql.jdbc.Driver");
            connection = DriverManager.getConnection(connectionURL, "root", "");
            //Add the data into the database
            String sql = "SELECT userid, password FROM login";
            Statement s = connection.createStatement();
            s.executeQuery(sql);
            rs = s.getResultSet();

            while(rs.next()) {
                userid = rs.getString("userid");
                password = rs.getString("password");
            }
            rs.close();
            s.close();

        } catch(Exception e) {
            System.out.println("Exception is: " + e);
          }

            if(userid.equals(request.getParameter("userid")) && password.equals(request.getParameter("password"))) {
                out.println("The user is valid");
            } 
            else {
                out.println("You are not valid");
            }
    }

}

Answer 1

在此代码中，您将用户输入值与表的最后一行数据进行比较....在while循环内写入比较代码以比较所有值....并在任何值与数据库值匹配时进行重定向... .....

package jsp;

import java.io.*;
//import java.util.*;
import java.sql.*;

import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import javax.servlet.*;

 @WebServlet(urlPatterns = {"/LoginValidation"})
public class Validation extends HttpServlet {

private static final long serialVersionUID = 1L;
private ServletConfig config;

public void init (ServletConfig config) 
throws ServletException{
    this.config = config;
}

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


    PrintWriter out = response.getWriter();
    String connectionURL = "jdbc:mysql://localhost/dblogin";
    Connection connection = null;
    ResultSet rs;
    String userid = new String("");
    String password = new String("");

    response.setContentType("text/html");
    try {
        // Load the database driver
        Class.forName("com.mysql.jdbc.Driver");
        connection = DriverManager.getConnection(connectionURL, "root", "");
        //Add the data into the database
        String sql = "SELECT userid, password FROM login";
        Statement s = connection.createStatement();
        s.executeQuery(sql);
        rs = s.getResultSet();

        while(rs.next()) {
            userid = rs.getString("userid");
            password = rs.getString("password");

                if(userid.equals(request.getParameter("userid")) && password.equals(request.getParameter("password"))) 
                {
                    out.println("The user is valid");

                    //Write exit program code or rediraction code here
                } 

        }
        rs.close();
        s.close();

    } catch(Exception e) {
        System.out.println("Exception is: " + e);
      }


 }

}

//我认为这不是一种有效的登录方式........但我只是在你的类型登录中给你问题解决方案.........

登录在我的servlet程序中不起作用

1 个答案: