我正在尝试用数据库中的数据验证在JSP页面中输入的用户名和密码，所有参数都来了，但是即使匹配数据，该函数也会返回false。我的错是什么？
这是我的代码：
public class LoginService {
public boolean loginCheck(String username, String password){
String query;
String dbUsername, dbPassword;
boolean login = false;
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/blog_u", "root", "root");
Statement stmt = (Statement) con.createStatement();
query = "SELECT username, password FROM user;";
stmt.executeQuery(query);
ResultSet rs = stmt.getResultSet();
while(rs.next()){
dbUsername = rs.getString("username");
dbPassword = rs.getString("password");
if(dbUsername == username && dbPassword == password){
System.out.println("OK");
login = true;
}
System.out.println(username + password + " " + dbUsername + dbPassword);
}
} catch (InstantiationException e) {
e.printStackTrace();
} catch (IllegalAccessException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return login;
}
}