java轉換日期的工具類

    import java.sql.Timestamp;

    import java.text.SimpleDateFormat;

    import java.util.Calendar;

    import java.util.Date;

    import java.util.regex.Pattern;


import org.apache.commons.lang.StringUtils;  
import org.apache.commons.logging.Log;  
import org.apache.commons.logging.LogFactory;  

public class DateUtils {  
    private static Log log = LogFactory.getLog(DateUtils.class);  
    public final static SimpleDateFormat dateMillTimeFormat = new SimpleDateFormat(  
            "yyyyMMddHHmmssSSS");  
    public final static SimpleDateFormat dateTimeFormat = new SimpleDateFormat(  
            "yyyy-MM-dd HH:mm:ss.SSS");  
    public final static java.util.regex.Pattern pattern = Pattern  
            .compile("^[0-9]{4}[/-][0-9]{1,2}[/-][0-9]{1,2}( +[0-9]{2}(:[0-9]{2}(:[0-9]{2}\\.?[0-9]{0,3})?)?)?$");  

    public synchronized static Date toDate(String date) {  
        Date d = null;  
        // 20110201==>yyyyMMdd  
        // 2011/01/01==>yyyy/MM/dd  
        // 2011-01-01==>yyyy-MM-dd  
        try {  
            if (!pattern.matcher(date).matches()) {  
                throw new Exception(date+" is not a date format.");  
            }  
            String rdate = date.replaceAll("[/ :.-]", "");  
            if (rdate.length() < 8) {  
                throw new Exception();  
            } else {  
                while (rdate.length() < 17) {  
                    rdate += "0";  
                }  
            }  
            d = dateMillTimeFormat.parse(rdate);  
        } catch (Exception e) {  
            log.error(date + " 日期格式錯誤.");  
        }  
        return d;  
    }  

    public static Date toDate(Timestamp date) {  
        return date;  
    }  

    public static Date toDate(Object date) {  
        Date d = null;  
        if (date instanceof Date) {  
            d = (Date) date;  
        } else if (date instanceof String) {  
            d = toDate((String) date);  
        }  
        return d;  
    }  
    public static Timestamp toTimeStamp(Object obj){  
        if (obj==null || StringUtils.isBlank(obj.toString())){  
            return null;  
        }  
        Date date = toDate(obj);  
        return new Timestamp(date.getTime());  
    }  
    public synchronized static String format(Date date) {  
        return dateTimeFormat.format(date);  
    }  

    public synchronized static String format(Timestamp date) {  
        return dateTimeFormat.format(date);  
    }  
    public static String format(Date date, String format) {  
        return new SimpleDateFormat(format).format(date);  
    }  

    public synchronized static String format(Object date) {  
        String formatDate = null;  
        if (date instanceof Date) {  
            formatDate = dateTimeFormat.format((Date) date);  
        }  
        return formatDate;  
    }  

    public static void main(String[] args) {  
        System.out.println("1:" + DateUtils.toDate("2011"));  
        System.out.println("2:" + DateUtils.toDate("2011/12/20"));  
        System.out.println("3:" + DateUtils.toDate("2011/12/20 17:20:30"));  
        System.out.println("4:" + DateUtils.toDate("2011/12/20 17:20"));  
        System.out.println("5:"  
                + DateUtils.toDate(new Timestamp(Calendar.getInstance()  
                        .getTime().getTime())));  
        System.out.println("6:"  
                + DateUtils.format(new Timestamp(Calendar.getInstance()  
                        .getTime().getTime())));  

        System.out.println("10:" + DateUtils.toDate("2010/12/01"));  
        System.out.println("11:" + DateUtils.toDate("2011-01-01"));  
        System.out.println("12:" + DateUtils.toDate("2010-10-11 15:20:15"));  
        System.out.println("13:" + DateUtils.toDate("2010-10-11 15:20"));  
        System.out.println("14:" + DateUtils.toDate("2010-10-11 15"));  
        System.out.println("15:" + DateUtils.toDate("2010-10-11 15:20:15.235"));  
        System.out.println("16:" + DateUtils.toDate("2010-10-11 15:20:15"));  
        System.out.println("17:" + DateUtils.toDate("2010-10-11 15:20:15"));  
        System.out.println("18:" + DateUtils.toDate("15:12:30"));  
        System.out.println("19:" + DateUtils.toDate("15:12:30.563"));  
    }  
}  </pre><br />