数字和字符串长度不够补0

import org.apache.commons.lang.StringUtils;

import java.text.DecimalFormat;
import java.util.regex.Pattern;

/**
 * @version V1.0
 * @Title: 数字和字符串长度不够补0
 * @ClassName: com.newcapec.util.sys
 * @Description: 参考-http://blog.sina.com.cn/s/blog_69398ed90102vsmt.html
 * @Copyright 2016-2017  Powered By 研发中心
 * @author: FLY
 * @date:2017/11/9 7:26
 */
public class CommonUtils {

    /**
     * 判断字符串是否为数字
     */
    private static Pattern NUMBER_PATTERN = Pattern.compile("^[-\\+]?[\\d]*$");

    /**
    * 长度为4位
    */
    private static final String STR_FORMAT = "0000";

    /**
     * @param str
     * @param strLength
     * @return java.lang.String
     * @Title: Java字符串长度不够前面或后面补0
     * @methodName: addZeroForNum
     * @Description:
     * @author: 王延飞
     * @date: 2017-11-08 17:28
     */
    public static String addZeroForNum(String str, int strLength) {

        if (StringUtils.isEmpty(str)) {
            return "";
        }

        int strLen = str.length();
        StringBuffer sb = null;
        while (strLen < strLength) {
            sb = new StringBuffer();
            // sb.append("0").append(str);// 左补0
            sb.append(str).append("0");//右补0
            str = sb.toString();
            strLen = str.length();
        }
        return str;
    }


    /**
     * @Title: 数字长度不够,前面补0方法
     * @methodName:  numPreAddZero
     * @param num
     * @param len
     * @return java.lang.String
     * @Description:
     *
     * @author: 王延飞
     * @date:  2017-11-09 7:44
     */
    public static String numPreAddZero(String num, int len) {

        boolean isNumeric = NUMBER_PATTERN.matcher(num).matches();
        if(!isNumeric){
            return "字符串不是数字";
        }
        Integer intHao = Integer.parseInt(num);
        intHao++;
        String strHao = intHao.toString();
        while (strHao.length() < len) {
            strHao = "0" + strHao;
        }
        return strHao;
    }

    /**
     * @Title: 数字长度不够,前面补0方法【用java中的DecimalFormat】
     * @methodName:  numPreAddZeroByDecimalFormat
     * @param num
     * @return java.lang.String
     * @Description:
     *
     * @author: FLY
     * @date:  2017-11-09 7:50
     */
    public static String numPreAddZeroByDecimalFormat(String num) {

        boolean isNumeric = NUMBER_PATTERN.matcher(num).matches();
        if(!isNumeric){
            return "字符串不是数字";
        }
        Integer parseInt = Integer.parseInt(num);
        DecimalFormat df = new DecimalFormat(STR_FORMAT);
        return df.format(parseInt);
    }

    public static void main(String[] args) {
        String addZeroForNum = addZeroForNum("34", 4);
        System.out.println("【Java字符串长度不够前面或后面补0】"+addZeroForNum);

        String codeAddOne = numPreAddZero("12ab", 5);
        System.out.println("【数字流水号长度不够补0方法】"+codeAddOne);

        String codeAddOne1 = numPreAddZero("12", 5);
        System.out.println("【数字流水号长度不够补0方法】"+codeAddOne1);

        String haoAddOne = numPreAddZeroByDecimalFormat("89");
        System.out.println("【用java中的DecimalFormat】"+haoAddOne);
    }
}