Date database date strings are converted to and from each other

date ：java.util.Date
Database date ：java.sql.Date

date Convert to Database date

• a key ： Dated getTime() Get timestamp , Convert to database date

        // util.Date --> sql.Date
        java.util.Date nowDate1 = new java.util.Date();
        java.sql.Date sqlDate = new java.sql.Date(nowDate1.getTime());
        System.out.println("sqlDate = " + sqlDate); 

Database date Convert to date

• a key ： Of database date getTime() Get timestamp , Convert to date

java.util.Date Date = new java.util.Date(sqlDate.getTime());

date Convert to character string

• a key ：SimpleDateFormat Class format() Method

        // util.Date --> String
        java.util.Date nowDate = new java.util.Date();
        SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd"); // Formatting tool 
        SimpleDateFormat sf1 = new SimpleDateFormat("yyyy year MM month dd Japan  HH spot mm branch ss second ");
        String format = sf.format(nowDate);
        System.out.println("format = " + format);
        String format1 = sf1.format(nowDate);
        System.out.println("format1 = " + format1);

character string Convert to date

• a key ： The format of the parameter defined in the formatting tool must be the same as that of the string

        SimpleDateFormat sf = new SimpleDateFormat("yyyy/MM/dd"); // Formatting tool 
        String stDate = "2020/01/01"; //  character string 
        java.util.Date parseDate = sf.parse(stDate);
        System.out.println("parseDate = " + parseDate);

        SimpleDateFormat sf1 = new SimpleDateFormat("yyyy year MM month dd Japan  HH spot mm branch ss second ");
        String stDate1 = "2021 year 3 month 20 Japan  19 spot 20 branch 30 second ";
        java.util.Date parseDate1 = sf1.parse(stDate1);
        System.out.println("parseDate1 = " + parseDate1);

Database date Convert to character string

• It is the same method as converting a date to a string

        java.util.Date nowDate = new java.util.Date();
        java.sql.Date sqlDate = new java.sql.Date(nowDate.getTime());
        SimpleDateFormat sf = new SimpleDateFormat("yyyy/MM/dd"); // Formatting tool 
        SimpleDateFormat sf1 = new SimpleDateFormat("yyyy year MM month dd Japan  HH spot mm branch ss second ");
        String format = sf.format(sqlDate);
        String format1 = sf1.format(sqlDate);
        System.out.println("format = " + format);
        System.out.println("format1 = " + format1);

• Of database date toString() Method
  The output only has month, year and day , Can't make time, minutes and seconds

	    java.sql.Date sqlDate = new java.sql.Date(new java.util.Date().getTime());
        System.out.println("sqlDate = " + sqlDate); 

character string Convert to Database date

• At present, it will not be directly transferred to , Only through date transit

LocalDate And sql.Date transformation

sql.Date Class about LocalDate There are only these two methods

LocalDate Convert to Database date

• Only about... In the database date date No datetime, Want to display hours, minutes and seconds , Probably still util.date

        LocalDate nowLocalDate = LocalDate.now();
        Date date = Date.valueOf(nowLocalDate);
        System.out.println("date = " + date);

Database date Convert to LocalDate

	LocalDate localDate = sqlDate.toLocalDate();