如何比较mySQL中的日期和java中的当前日期？ [英] How to compare a date from mySQL from the current date in java?

问题描述

我正在使用MVC模式在Java EE中编写一个简单的登录程序，我希望提醒用户他/她的密码已超过一年。目前我可以从数据库中获取数据，并将其转换为字符串，但之后我不知道如何将其与当前日期进行比较。

I am writing a simple log-in program in Java EE using the MVC pattern, and I wish to alert the user that his/her password is over a year old. Currently I can get the data from the database, and convert it into a string, but after that I don't know how to compare it to current date.

这是到目前为止我所拥有的：

This is what I have so far:

public String validateAccount(String email, String enterPassword) {

        try {
            Class.forName(driverName).newInstance();
        } catch (InstantiationException | IllegalAccessException
                | ClassNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        Connection connection;

        try {

            connection = DriverManager.getConnection(dbURL, username, password);

            // Retrive current user data from database
            String getCredentials = "SELECT id,dateSet,strength FROM users WHERE email=? AND hashPassword=SHA2(CONCAT(?, salt), 256)";
            PreparedStatement verifyCredentials = connection
                    .prepareStatement(getCredentials);
            verifyCredentials.setString(1, email);
            verifyCredentials.setString(2, enterPassword);
            ResultSet foundData = verifyCredentials.executeQuery();

            while (foundData.next()) {
                System.out.println("Found account");
                int id = foundData.getInt("id");
                String dateSet = foundData.getString("dateSet");
                String strength = foundData.getString("strength");

                // ... do something with these variables ... if
                if (strength.equals("Weak")) {
                    return "1";

                } else if (/*Check if the date in the database is over a year old, and return 2*/) {
                    return "2";
                } else {
                    return "0";
                }

            }
            foundData.close();

            return "Account not found, re-enter your info again";

        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return "";

    }

推荐答案

你可以使用foundData.getTimestamp（）代替，并获取一个时间戳，你可以将其转换为普通的java数据类:)。

You can use foundData.getTimestamp() instead, and get a timestamp, which you can convert into a normal java Data class :)

所以，你会有像

So, you would have something like

Date dateSet = new Date(foundData.getTimestamp("dateSet").getTime());

或者，如果您不熟悉使用Date实例（您需要使用日历也可以直接在你的SQL查询中进行检查，

or alternatively, if you are not familiar with working with Date instances (you'll need to use a Calendar as well) you can do the check directly in your SQL query,

String getCredentials = "SELECT id,dateSet,strength, IF(dateSet < NOW() - INTERVAL 1 YEAR, TRUE, FALSE) AS oldPasswd FROM users WHERE email=? AND hashPassword=SHA2(CONCAT(?, salt), 256)";

然后

else if (foundData.getBoolean("oldPasswd")) {
   return "2";
}

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