登录表单错误+ JDBC CONNECTIVITY（JAVA-MYSQL）

Question

我有一个具有JDBC连接（JAVA-MYSQL）的项目，该项目具有登录表单。 但是编码不起作用。（这意味着它始终显示“ WRONG PASSWORD”（错误密码），尽管我确定它是正确的）。

请找到错误。 （因为它没有显示）。

 private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) { String S; String email = jTextField3.getText(); try { Class.forName("java.sql.Driver"); Connection con = DriverManager.getConnection("jdbc:Mysql://localhost/nami", "root", "123456"); Statement st = con.createStatement(); S = "SELECT password FROM signup WHERE email =" + "'" + email + "'" + ";"; st.executeQuery(S); String pass = new String(jPasswordField2.getPassword()); if (pass.equals("S")) { jOptionPane1.showMessageDialog(null, "YOU HAVE SUCCESSFULLY LOGGED IN"); MAINPAGE at = new MAINPAGE(); jDesktopPane1.add(at); at.show(); } else { jOptionPane1.showMessageDialog(null, "WRONG PASSWORD!!"); } } catch (Exception e) { jOptionPane2.showMessageDialog(null, "Error" + e.getMessage()); } } 

Answer 1

pass.equals("S")表示您的密码应始终为S才能成功登录。

您需要从数据库中查询，然后进行比较。

Result rs = st.executeQuery(S);
String queryPass = null;
if(rs.next()){
   queryPass = rs.getString("password");
}

if (pass.equals(queryPass)) {
  jOptionPane1.showMessageDialog(null, "YOU HAVE SUCCESSFULLY LOGGED IN");
  MAINPAGE at = new MAINPAGE();
  jDesktopPane1.add(at);
  at.show();

} else {
  jOptionPane1.showMessageDialog(null, "WRONG PASSWORD!!");
}

顺便说一句，将参数直接传递到sql中是一个坏主意，您需要使用PreparedStatement而不是Statement来避免SQL注入

Answer 2

＃＃ 尝试这个 ＃＃

 String email=request.getParameter("email");
   String pass=request.getParameter("pass");



                     Class.forName("com.mysql.jdbc.Driver");
                     Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/users_record","root","root");
                     Statement st1=con.createStatement();
                     ResultSet obj1=st1.executeQuery("select * from registration where email='" +email+ "'");

                     System.out.println(email);        
                     while(obj1.next())
                        {

                             String p2=obj1.getString(5);
                             if(p2.equals(pass))
                                 {

                                     response.sendRedirect("home1.jsp?msg=YOU HAVE SUCCESSFULLY LOGGED IN ");


                                 }
                             else
                                 {
                                       response.sendRedirect("login1.jsp?msg=Invalid password");
                                 }
                        }