Java中的JSP登录问题

Question

I have created a login session in JSP which is connected to a database.

I have 3 rows of in my admin table. The problem is that when I enter the correct credentials as they are in the table, it does nothing when I login. Its only when I enter the last row (username and password) of the admin table, that it logs me in successfully. But when I enter the previous usernames and passwords which are in the table, it does not log me in. Why is that so? My codes are below:

LoginManager.java

public class LoginManager {

String url = "jdbc:mysql://localhost:3306/cms";
String user = "root";
String pass = "root";


    ArrayList<Login> lgs = new ArrayList<Login>();
    public ArrayList<Login> log(String userType, String username, String password) throws ClassNotFoundException, SQLException{
        Class.forName("com.mysql.jdbc.Driver");
        Connection con = DriverManager.getConnection(url, user, pass);
        Statement stt = con.createStatement();
        if(userType.equals("Administrator")){
            String admin = "SELECT * FROM admin";
            ResultSet rs = stt.executeQuery(admin);
            while(rs.next()){
                String logid = rs.getString("LoginName");
                String pw = rs.getString("Password");
                String fname = rs.getString("FirstName");
                String lname = rs.getString("LastName");
            Login lg = new Login();
            lg.setUsername(logid);
            lg.setPassword(pw);
            lg.setFname(fname);
            lg.setLname(lname);
            lg.setUserType("Administrator");
            lgs.add(lg);
            }
            con.close();
            rs.close();
            stt.close();
        }

        return lgs;
    }

Login.java

  package cms;

  import javax.persistence.*;

    @Entity
    public class Login {
private String userType;
private String username;
private String password;
private String fname;
private String lname;

@Id
public String getUserType() {
    return userType;
}
public void setUserType(String userType) {
    this.userType = userType;
}
public String getUsername() {
    return username;
}
public void setUsername(String username) {
    this.username = username;
}
public String getPassword() {
    return password;
}
public void setPassword(String password) {
    this.password = password;
}

public void setFname(String fname){
    this.fname = fname;
}

public String getFname(){
    return fname;
}

public void setLname(String lname){
    this.lname = lname;
}

public String getLname(){
    return lname;
  }
   }

Part of the JSP Code

    <%@page import = "java.util.*, cms.*" %>
<jsp:useBean id = "lm" class = "cms.LoginManager" scope = "session"/>

      <%
    Boolean submitted = Boolean.parseBoolean(request.getParameter("isSubmitted"));
  int success = 0;
      if(submitted){
  String type = request.getParameter("type");
  String user = request.getParameter("userInput");
  String password = request.getParameter("pw");
 ArrayList<Login> lgs = lm.log(type, user, password);

 Login lg = new Login();
for(int i=0; i <lgs.size(); i++)
 lg= lgs.get(i);


 if((user.equals(lg.getUsername()) && password.equals(lg.getPassword()) && type.equals("Administrator"))){
    session.setAttribute("name", lg.getFname() + " " + lg.getLname());
    session.setAttribute("type", lg.getUserType());
     response.sendRedirect("index.jsp");
 }else{

 }

Answer 1

you are having logical bug in your jsp code. first you are iterating through all users and then you are validating the user. make it something like this and it will work

   Login lg = new Login();
    for(int i=0; i <lgs.size(); i++){
     lg= lgs.get(i);
    if((user.equals(lg.getUsername()) && password.equals(lg.getPassword()) && type.equals("Administrator"))){
    session.setAttribute("name", lg.getFname() + " " + lg.getLname());
    session.setAttribute("type", lg.getUserType());
     response.sendRedirect("index.jsp");
 }else{

 }
}