工具类积累

MD5工具类

package com.itheima.utils;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class MD5Utils {
   /**
    * 使用md5的算法进行加密
    */
   public static String md5(String plainText) {
      byte[] secretBytes = null;
      try {
         secretBytes = MessageDigest.getInstance("md5").digest(
               plainText.getBytes());
      } catch (NoSuchAlgorithmException e) {
         throw new RuntimeException("没有md5这个算法！");
      }
      String md5code = new BigInteger(1, secretBytes).toString(16);// 16进制数字
      // 如果生成数字未满32位，需要前面补0
      for (int i = 0; i < 32 - md5code.length(); i++) {
         md5code = "0" + md5code;
      }
      return md5code;
   }

   public static void main(String[] args) {
      System.out.println(md5("1234"));
   }

}

日期工具类

package com.itheima.utils;

import java.text.SimpleDateFormat;
import java.util.*;

/**
 * 日期操作工具类
 */
public class DateUtils {
    /**
     * 日期转换-  String -> Date
     *
     * @param dateString 字符串时间
     * @return Date类型信息
     * @throws Exception 抛出异常
     */
    public static Date parseString2Date(String dateString) throws Exception {
        if (dateString == null) {
            return null;
        }
        return parseString2Date(dateString, "yyyy-MM-dd");
    }

    /**
     * 日期转换-  String -> Date
     *
     * @param dateString 字符串时间
     * @param pattern    格式模板
     * @return Date类型信息
     * @throws Exception 抛出异常
     */
    public static Date parseString2Date(String dateString, String pattern) throws Exception {
        if (dateString == null) {
            return null;
        }
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        Date date = sdf.parse(dateString);
        return date;
    }

    /**
     * 日期转换 Date -> String
     *
     * @param date Date类型信息
     * @return 字符串时间
     * @throws Exception 抛出异常
     */
    public static String parseDate2String(Date date) throws Exception {
        if (date == null) {
            return null;
        }
        return parseDate2String(date, "yyyy-MM-dd");
    }

    /**
     * 日期转换 Date -> String
     *
     * @param date    Date类型信息
     * @param pattern 格式模板
     * @return 字符串时间
     * @throws Exception 抛出异常
     */
    public static String parseDate2String(Date date, String pattern) throws Exception {
        if (date == null) {
            return null;
        }
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        String strDate = sdf.format(date);
        return strDate;
    }

    /**
     * 获取当前日期的本周一是几号
     *
     * @return 本周一的日期
     */
    public static Date getThisWeekMonday() {
        Calendar cal = Calendar.getInstance();
        cal.setTime(new Date());
        // 获得当前日期是一个星期的第几天
        int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
        if (1 == dayWeek) {
            cal.add(Calendar.DAY_OF_MONTH, -1);
        }
        // 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
        cal.setFirstDayOfWeek(Calendar.MONDAY);
        // 获得当前日期是一个星期的第几天
        int day = cal.get(Calendar.DAY_OF_WEEK);
        // 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
        return cal.getTime();
    }

    /**
     * 获取当前日期周的最后一天
     *
     * @return 当前日期周的最后一天
     */
    public static Date getSundayOfThisWeek() {
        Calendar c = Calendar.getInstance();
        int dayOfWeek = c.get(Calendar.DAY_OF_WEEK) - 1;
        if (dayOfWeek == 0) {
            dayOfWeek = 7;
        }
        c.add(Calendar.DATE, -dayOfWeek + 7);
        return c.getTime();
    }

    /**
     * 根据日期区间获取月份列表
     *
     * @param minDate 开始时间
     * @param maxDate 结束时间
     * @return 月份列表
     * @throws Exception
     */
    public static List<String> getMonthBetween(String minDate, String maxDate, String format) throws Exception {
        ArrayList<String> result = new ArrayList<>();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");

        Calendar min = Calendar.getInstance();
        Calendar max = Calendar.getInstance();

        min.setTime(sdf.parse(minDate));
        min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), 1);

        max.setTime(sdf.parse(maxDate));
        max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), 2);
        SimpleDateFormat sdf2 = new SimpleDateFormat(format);

        Calendar curr = min;
        while (curr.before(max)) {
            result.add(sdf2.format(curr.getTime()));
            curr.add(Calendar.MONTH, 1);
        }

        return result;
    }

    /**
     * 根据日期获取年度中的周索引
     *
     * @param date 日期
     * @return 周索引
     * @throws Exception
     */
    public static Integer getWeekOfYear(String date) throws Exception {
        Date useDate = parseString2Date(date);
        Calendar cal = Calendar.getInstance();
        cal.setTime(useDate);
        return cal.get(Calendar.WEEK_OF_YEAR);
    }

    /**
     * 根据年份获取年中周列表
     *
     * @param year 年分
     * @return 周列表
     * @throws Exception
     */
    public static Map<Integer, String> getWeeksOfYear(String year) throws Exception {
        Date useDate = parseString2Date(year, "yyyy");
        Calendar cal = Calendar.getInstance();
        cal.setTime(useDate);
        //获取年中周数量
        int weeksCount = cal.getWeeksInWeekYear();
        Map<Integer, String> mapWeeks = new HashMap<>(55);
        for (int i = 0; i < weeksCount; i++) {
            cal.get(Calendar.DAY_OF_YEAR);
            mapWeeks.put(i + 1, parseDate2String(getFirstDayOfWeek(cal.get(Calendar.YEAR), i)));
        }
        return mapWeeks;
    }

    /**
     * 获取某年的第几周的开始日期
     *
     * @param year 年分
     * @param week 周索引
     * @return 开始日期
     * @throws Exception
     */
    public static Date getFirstDayOfWeek(int year, int week) throws Exception {
        Calendar c = new GregorianCalendar();
        c.set(Calendar.YEAR, year);
        c.set(Calendar.MONTH, Calendar.JANUARY);
        c.set(Calendar.DATE, 1);

        Calendar cal = (GregorianCalendar) c.clone();
        cal.add(Calendar.DATE, week * 7);

        return getFirstDayOfWeek(cal.getTime());
    }

    /**
     * 获取某年的第几周的结束日期
     *
     * @param year 年份
     * @param week 周索引
     * @return 结束日期
     * @throws Exception
     */
    public static Date getLastDayOfWeek(int year, int week) throws Exception {
        Calendar c = new GregorianCalendar();
        c.set(Calendar.YEAR, year);
        c.set(Calendar.MONTH, Calendar.JANUARY);
        c.set(Calendar.DATE, 1);

        Calendar cal = (GregorianCalendar) c.clone();
        cal.add(Calendar.DATE, week * 7);

        return getLastDayOfWeek(cal.getTime());
    }

    /**
     * 获取当前时间所在周的开始日期
     *
     * @param date 当前时间
     * @return 开始时间
     */
    public static Date getFirstDayOfWeek(Date date) {
        Calendar c = new GregorianCalendar();
        c.setFirstDayOfWeek(Calendar.SUNDAY);
        c.setTime(date);
        c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek());
        return c.getTime();
    }

    /**
     * 获取当前时间所在周的结束日期
     *
     * @param date 当前时间
     * @return 结束日期
     */
    public static Date getLastDayOfWeek(Date date) {
        Calendar c = new GregorianCalendar();
        c.setFirstDayOfWeek(Calendar.SUNDAY);
        c.setTime(date);
        c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6);
        return c.getTime();
    }
    //获得上周一的日期
    public static Date geLastWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(getThisWeekMonday(date));
        cal.add(Calendar.DATE, -7);
        return cal.getTime();
    }

    //获得本周一的日期
    public static Date getThisWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        // 获得当前日期是一个星期的第几天
        int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
        if (1 == dayWeek) {
            cal.add(Calendar.DAY_OF_MONTH, -1);
        }
        // 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
        cal.setFirstDayOfWeek(Calendar.MONDAY);
        // 获得当前日期是一个星期的第几天
        int day = cal.get(Calendar.DAY_OF_WEEK);
        // 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
        return cal.getTime();
    }

    //获得下周一的日期
    public static Date getNextWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(getThisWeekMonday(date));
        cal.add(Calendar.DATE, 7);
        return cal.getTime();
    }

    //获得今天日期
    public static Date getToday(){
        return new Date();
    }

    //获得本月一日的日期
    public static Date getFirstDay4ThisMonth(){
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_MONTH,1);
        return calendar.getTime();
    }

    public static void main(String[] args) {
        try {
            System.out.println("本周一" + parseDate2String(getThisWeekMonday()));
            System.out.println("本月一日" + parseDate2String(getFirstDay4ThisMonth()));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

随机生成验证码工具类

package com.itheima.utils;

import java.util.Random;

/**
 * 随机生成验证码工具类
 */
public class ValidateCodeUtils {
    /**
     * 随机生成验证码
     * @param length 长度为4位或者6位
     * @return
     */
    public static Integer generateValidateCode(int length){
        Integer code =null;
        if(length == 4){
            code = new Random().nextInt(9999);//生成随机数，最大为9999
            if(code < 1000){
                code = code + 1000;//保证随机数为4位数字
            }
        }else if(length == 6){
            code = new Random().nextInt(999999);//生成随机数，最大为999999
            if(code < 100000){
                code = code + 100000;//保证随机数为6位数字
            }
        }else{
            throw new RuntimeException("只能生成4位或6位数字验证码");
        }
        return code;
    }

    /**
     * 随机生成指定长度字符串验证码
     * @param length 长度
     * @return
     */
    public static String generateValidateCode4String(int length){
        Random rdm = new Random();
        String hash1 = Integer.toHexString(rdm.nextInt());
        String capstr = hash1.substring(0, length);
        return capstr;
    }
}