随机生成字母数字的组合

ゝ一纸荒年。 2022-06-12 04:38 236阅读 0赞

![20170715172344619][]

随机数和随机字符串在开发中频繁的使用，本篇的demo可以直接封装成为一个实体类，使用的时候直接调用里面的对应方法即可

import java.util.Random;
     
    public class StringUtil {
        private static final int Num_WORD = 1;//数字
        private static final int STR_WORD = 2;//字母
        private static final int STR_NUM_WORD = 3;//字母数字
        private static final int MIX_WORD = 4;//字母数字符号
     
        /**
         * 获取随机字符串
         * @param style  输出格式  1纯数字，2纯字符串，3字符数字组合，4字符数字符号组合。
         * @param length 输出长度
         * */
     
        public static String getRandomStr(int style, int length) {
     
             if (style == Num_WORD) {
                    return getNumRandom(length);
                } else if (style == STR_WORD) {
                    return getStrRandom(length);
                } else if (style == STR_NUM_WORD) {
                    return getStrNumRandom(length);
                }else if (style == MIX_WORD) {
                    return getMixRandom(length);
                }else{
     
                     return getMixRandom(length);
     
                 }
          
        }
     
        //纯数字
        private static String getNumRandom(int length) {
            int[] array = new int[length];
            StringBuilder str = new StringBuilder();
            for (int i = 0; i < length; i++) {
                array[i] = (int) (Math.random() * 10);
                str.append(array[i]);
            }
            return str.toString();
        }
     
        //纯字母
        private static String getStrRandom(int length) {
            int[] array = new int[length];
            char[] chars = new char[length];
            StringBuilder str = new StringBuilder();
            for (int i = 0; i < length; i++) {
                while (true) {
                    array[i] = (int) (Math.random() * 1000);
                    if ((array[i] > 64 && array[i] < 91)
                            || (array[i] > 96 && array[i] < 123))
                        break;
                }
                chars[i] = (char) array[i];
                str.append(chars[i]);
            }
            return str.toString();
        }
     
        //字母数字组合
        public static String getStrNumRandom(Integer length) { 
            StringBuilder str = new StringBuilder();
            Random random = new Random(); 
            for (int i = 0; i < length; i++) { 
                boolean b = random.nextBoolean(); 
                if (b) { // 字符串 
                    int choice = random.nextBoolean() ? 65 : 97; //取得65大写字母还是97小写字母 
                    str.append((char) (choice + random.nextInt(26)));// 取得大写字母 
                } else { // 数字 
                    str.append(random.nextInt(10)); 
                } 
            } 
            return str.toString(); 
        } 
         
        //字母数字符号组合
        private static String getMixRandom(int length) {
            int[] array = new int[length];
            char[] chars = new char[length];
            StringBuilder str = new StringBuilder();
     
            for (int i = 0; i < length; i++) {
                while (true) {
                    array[i] = (int) (Math.random() * 1000);
                    if (array[i] > 47 && array[i] < 91 || (array[i] > 96 && array[i] < 123))
                        break;
                }
                chars[i] = (char) array[i];
                str.append(chars[i]);
            }
            return str.toString();
        }
         
        public static void main(String[] args) {
            System.out.println(StringUtil.getRandomStr(4, 10));
        }
    }

[20170715172344619]: /images/20220612/e5b59075eef74a8983b87e7d8dc5d48e.png