SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    String date = "2010-05-30 22:15:52";
    java.util.Date formatedDate = sdf.parse(date); // returns a String when it is parsed
    System.out.println(sdf.format(formatedDate)); // the use of format function returns a String

Date date = new Date();
String strDate = String.format("%tY-%<tm-%<td %<tH:%<tM:%<tS", date);

Format formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String s = formatter.format(date);

common -lang DateFormatUtils充满了好东西(如果你的类路径中有common -lang)

//Formats a date/time into a specific pattern
 DateFormatUtils.format(yourDate, "yyyy-MM-dd HH:mm:SS");

public static String formateDate(String dateString) {
    Date date;
    String formattedDate = "";
    try {
        date = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss",Locale.getDefault()).parse(dateString);
        formattedDate = new SimpleDateFormat("dd/MM/yyyy",Locale.getDefault()).format(date);
    } catch (ParseException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return formattedDate;
}

为什么不用Joda (org.joda.time.DateTime)? 基本上就是一行代码。

Date currentDate = GregorianCalendar.getInstance().getTime();
String output = new DateTime( currentDate ).toString("yyyy-MM-dd HH:mm:ss");

// output: 2014-11-14 14:05:09