英文:
Problem connecting a login method in my Java program to MySQL table using JDBC
问题
我正在编写一个Java程序（使用Java Swing和JDBC），在其中一个面板中，我有一个登录界面。我希望我的程序可以比较输入的用户名和密码，并将其与我在数据库表（MySQL）中拥有的用户名和密码进行比较。以下是我在“登录”按钮中编写的代码，您可以自行查看：
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
String url2 = "jdbc:mysql://localhost:3306/Students?user=root";
Connection connect2 = DriverManager.getConnection(url2);
Statement state2 = connect2.createStatement();
String query2 = "select * from login_data where username='%s'";
query2 = String.format(query2, username1.getText());
ResultSet result2 = state2.executeQuery(query2);
if (result2.next()) {
if (result2.getString("password").equals(password1.getText())) {
login.setVisible(false);
Mainmenu();
} else {
result1.setText("Wrong Password");
}
} else {
result1.setText("Wrong Username!!!");
}
state2.close();
connect2.close();
} catch (SQLException e1) {
e1.printStackTrace();
} catch (IllegalAccessException e1) {
e1.printStackTrace();
} catch (InstantiationException e1) {
e1.printStackTrace();
} catch (ClassNotFoundException e1) {
e1.printStackTrace();
}
现在，如果我提供了错误的用户名，它会正确显示“错误的用户名”消息。然而，如果用户名是正确的，它会显示“错误的密码”消息。无论密码是否正确都会如此。
我感觉这里有一个逻辑错误，但我看不到它。
英文:
I'm writing a Java program (with Java Swing and JDBC) and in one of my panels, I have a login. I want my program to compare the entered username and password and compare it to the ones U have in my database table (MySQL). This is what I wrote in my "Login" button, see for yourself:
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
String url2 = "jdbc:mysql://localhost:3306/Students?user=root";
Connection connect2 = DriverManager.getConnection(url2);
Statement state2 = connect2.createStatement();
String query2 = "select * from login_data where username='%s'";
query2 = String.format(query2,username1.getText());
ResultSet result2 = state2.executeQuery(query2);
if(result2.next()){
if(result2.getString("password")==password1.getText()){
login.setVisible(false);
Mainmenu();
}else{
result1.setText("Wrong Password");
}
}else{
result1.setText("Wrong Username!!!");
}
state2.close();
connect2.close();
} catch (SQLException e1) {
e1.printStackTrace();
} catch (IllegalAccessException e1) {
e1.printStackTrace();
} catch (InstantiationException e1) {
e1.printStackTrace();
} catch (ClassNotFoundException e1) {
e1.printStackTrace();
}
Now, if I give it a wrong username, it correctly shows the "wrong username" message. However, if the username is correct, it shows the "wrong password" message. It doesn't matter if the password is/isn't correct.
I feel there is a logical error here, but I can't see it.
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