Question

这是一个登录表单的代码，我使用JDBC连接代码没有错误但是当我运行它时总是转到else语句

    Connection con;
    Statement st;
    ResultSet rs;
    try{
      Class.forName("java.sql.Driver");
      con=DriverManager.getConnection   ("jdbc:mysql://localhost/database","root","password");
      st=con.createStatement();
      rs=st.executeQuery("select * from users;");
      while(rs.next()){
                String userID=rs.getString("userID");
                String password=rs.getString("password");

                if(userID.equals(txtuserID.getText())
                    && (password.equals(txtpassword.getPassword())) {
                // ***HERE IS MY PROBLEM I WANT TO CHECK IF WHATS IN THE 
                // TEXT FIELD OR PASSWORD FIELD IS THE SAME FROM MySQL***
                    JOptionPane.showMessageDialog(null,"you have logged in");
                    new MainForm().setVisible(true);
                } else {
                    JOptionPane.showMessageDialog(null,"Incorrect username and password");
                }
     }
  } catch(Exception e) {
     JOptionPane.showMessageDialog(null,"Error in Connectivity: " +e.getMessage());
  }

Answer 1

JPasswordField getPassword（）方法返回char []。在比较之前转换为String :(实际上用这些chars构造一个新的String ...）

if(userID.equals(txtuserID.getText()) &&
  (password.equals(new String((txtpassword.getPassword()))) {
}

Answer 2

关于chenchuk的回答，将char数组保留为char数组并且不将它们转换为String可以更加安全，可以更容易地窃取它。

所以不要像在chenchuk的回答中那样将密码＆＃39的char []转换为String：

if(userID.equals(txtuserID.getText()) &&
  (password.equals(new String((txtpassword.getPassword()))) {
}

使用java.util.Arrays.equals(...)方法更安全：

if(userID.equals(txtuserID.getText()) 
        && Arrays.equals(txtpassword.getPassword(), password.toCharArray())) {

    // your code goes here
}

如何将文本字段和密码字段与字符串值进行比较？

2 个答案: