一个关于日期，数字，字符格式化的常用工具类

import java.text.SimpleDateFormat;
import java.text.ParseException;
import java.util.Calendar;
import java.util.Date;
import java.text.DecimalFormat;

import org.apache.commons.lang.StringUtils;

public class StrTool {

    /**
     * 日期格式化
     *
     * @param date
     *            Date
     * @param formatstr
     *            String
     * @return String
     */
    public static String formatDate(java.util.Date date, String formatstr) {
        if (date == null || formatstr == null)
            return null;
        java.text.SimpleDateFormat dateFormat = new SimpleDateFormat(formatstr);
        return dateFormat.format(date);
    }

    public static String formatDate(java.util.Date date) {
        return formatDate(date, "yyyy-MM-dd");
    }

    /**
     * 格式当前日期
     *
     * @return String
     */
    public static String formatDateByNow() {
        return formatDate(new java.util.Date());
    }

    public static String formatTime(java.util.Date date) {
        return formatDate(date, "kk:mm:ss");
    }

    public static String formatDateTime(java.util.Date date) {
        return formatDate(date, "yyyy-MM-dd kk:mm");
    }

    /**
     * 解释日期yyyy-MM-dd kk:mm
     *
     * @param strdate
     *            String
     * @return Date
     * @throws ParseException
     */
    public static java.util.Date parseDateTime(String strdate)
            throws ParseException {
        return parseDateTimeByFormatstr(strdate, "yyyy-MM-dd kk:mm");
    }

    /**
     * 解释日期yyyy-MM-dd
     *
     * @param strdate
     *            String
     * @return Date
     * @throws ParseException
     */
    public static java.util.Date parseDate(String strdate)
            throws ParseException {
        return parseDateTimeByFormatstr(strdate, "yyyy-MM-dd");
    }

    /**
     * 根据传入的格式化字串来解释日期
     *
     * @param strdate
     *            String
     * @param formatstr
     *            String
     * @return Date
     * @throws ParseException
     */
    public static java.util.Date parseDateTimeByFormatstr(String strdate,
            String formatstr) throws ParseException {
        java.text.SimpleDateFormat dateFormat = new SimpleDateFormat(formatstr);
        return dateFormat.parse(strdate);
    }

    /**
     * 格式数字类型
     *
     * @param f
     *            float
     * @param sacl
     *            int
     * @return String
     */
    public static String formatNumber(double f, String pattern) {
        java.text.DecimalFormat num = new DecimalFormat(pattern);
        return num.format(f);
    }

    /**
     * 格式化为钱格式显示如：1,234,555.00
     *
     * @param money
     *            double
     * @return String
     */
    public static String formatMoney(double money) {
        return formatNumber(money, "#,##0.00");
    }

    public static String indexUpStr(String str) {
        if (str == null || str.length() < 1) {
            return str;
        }
        String tmstr = "";
        tmstr = str.substring(0, 1);
        tmstr = tmstr.toUpperCase();
        tmstr += str.substring(1);
        return tmstr;
    }

    /**
     * 根据分隔符,将数字字符转换成整型数组
     *
     * @param str
     *            String
     * @param regex
     *            String
     * @return int[]
     */
    public static int[] toIntsByRegex(String str, String regex) {
        if (str == null || "".equals(str.trim()))
            return null;
        String[] tms = str.split(regex);
        int[] tmi = new int[tms.length];
        for (int i = 0; i < tms.length; i++) {
            tmi[i] = Integer.parseInt(tms[i]);
        }
        return tmi;
    }

    public static int[] toInts(String str) {
        return toIntsByRegex(str, ",");
    }

    /**
     * 将格式化的数字还原，如：1,234,567.00——>1234567.00
     *
     * @param formattedNumber
     * @return parseString
     */
    public static String parseFormattedNumber(String formattedNumber) {
        java.text.DecimalFormat num = new DecimalFormat();

        String parseString = "";
        try {
            parseString = formatNumber(Double.parseDouble(num.parse(
                    formattedNumber).toString()), "#0.00");
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return parseString;
    }

    public static void main(String[] args) throws ParseException {
        // System.out.println(indexUpStr("")+";");
        // toIntsByRegex(" ",",");

        // Date date = parseDateTime("2004-04-12 13:24");
        // System.out.println(formatDateTime(date));
        java.text.DecimalFormat num = new DecimalFormat();
        System.out.println(formatNumber(5234556, "#,##0.00%"));
        System.out.println(parseFormattedNumber("99999999"));
        System.out.println("interval: "
                + getIntervalOfDate("2005-05-01", "2006-06-12"));
    }

    /**
     * 将字符串数组转化为字符串,并用","连接
     *
     * @author 李奉学
     * @param arrayString
     * @return 带","分割的字符串
     */
    public static String convertArrayToString(String[] arrayString) {
        String returnString = "";

        if (arrayString != null) {
            for (int i = 0; i < arrayString.length; i++) {
                // 第一个元素前不能加","
                if (StringUtils.isEmpty(returnString)) {
                    returnString = returnString + arrayString[i];
                } else {
                    returnString = returnString + "," + arrayString[i];
                }
            }
        }
        return returnString;
    }

    public static String getFileExt(String filename) {
        String fileext = "";
        String tmfilename = filename;
        if (tmfilename != null) {
            int l = tmfilename.indexOf(".") + 1;
            if (l == 0) {
                return "";
            }
            int tml = l;
            while (tml != 0) {
                try {
                    l = tml;
                    tml = tmfilename.indexOf(".", tml) + 1;
                } catch (Exception e) {
                    tml = 0;
                }
            }
            int length = tmfilename.length();
            if (l <= length && l != 1) {
                fileext = tmfilename.substring(l);
            } else {
                fileext = "";
            }
        }
        return fileext;
    }

    /**
     * 补齐字符长度
     *
     * @param str
     * @param length
     * @param repair
     * @return
     */
    public static String fillStrLength(String str, int length, String repair) {
        for (int i = str.length(); i < length; i++) {
            str = repair + str;
        }
        return str;
    }

    /**
     * 比较字符串大小
     *
     * @param str1
     * @param str2
     * @return
     */
    public static int strComp(String str1, String str2) {
        if (str1 == null || str2 == null) {
            return 0;
        }
        int str1Length = str1.length();
        int str2Length = str2.length();
        if (str2Length > str1Length) {
            str1 = fillStrLength(str1, str2Length, "0");
        } else if (str2Length < str1Length) {
            str1 = fillStrLength(str2, str1Length, "0");
        }
        int result = str1.compareTo(str2);
        if (result >= 1)
            result = 1;
        if (result <= -1)
            result = -1;
        return result;
    }

    /**
     * xuxu 返回毫秒
     *
     * @param date
     * @return
     */
    public static long getMillis(Date date) {
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        return c.getTimeInMillis();
    }

    /**
     * 日期相减
     *
     * @param date
     *            日期
     * @param day
     *            天数
     * @return
     */
    public static Date subDate(Date date, int day) {
        Calendar c = Calendar.getInstance();
        c.setTimeInMillis(getMillis(date) - ((long) day) * 24 * 3600 * 1000);
        return c.getTime();
    }

    /**
     * 返回同一年内两个日期相差的天数
     *
     * @author 李奉学
     * @param date1
     * @param date2
     * @return 相差的天数
     * @throws ParseException
     */
    public static int getIntervalOfDate(String date1, String date2)
            throws ParseException {
        int interval = 0;
        // 设置日期
        Calendar cal1 = Calendar.getInstance();
        cal1.setTime(parseDate(date1));

        Calendar cal2 = Calendar.getInstance();
        cal2.setTime(parseDate(date2));

        // 相差的天数
        interval = Math.abs(cal1.get(Calendar.DAY_OF_YEAR)
                - cal2.get(Calendar.DAY_OF_YEAR));

        return interval;
    }

    /**
     * 当前日期在一年中的周序号
     *
     * @param date
     * @return 周序号
     * @throws ParseException
     */
    public static int getWeekIndexOfYear(String date) throws ParseException {
        int index = -1;

        Calendar cal = Calendar.getInstance();
        cal.setTime(parseDate(date));
       
        index=cal.get(Calendar.WEEK_OF_YEAR);
       
        return index;
    }

}