在工作中,需要随机产生数据库中的字符,以免主键冲突或者违反唯一性约束,特简单写了一个并在此记录一下,在这里产生的方式主要有两种,一种方法是通过随机产生一个个字符,另一种方法是通过UUID方式生成。
代码如下所示:
package com.bijian.test; import java.util.Random; import java.util.UUID; public class RandomUtils { public static final String allChar = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; public static final String letterChar = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; public static final String numberChar = "0123456789"; /** * 由大小写字母、数字组成的随机字符串 * @param length * @return */ public static String generateString(int length) { StringBuffer sb = new StringBuffer(); Random random = new Random(); for (int i = 0; i < length; i++) { sb.append(allChar.charAt(random.nextInt(allChar.length()))); } return sb.toString(); } /** * 由大小写字母组成的随机字符串 * @param length * @return */ public static String generateMixString(int length) { StringBuffer sb = new StringBuffer(); Random random = new Random(); for (int i = 0; i < length; i++) { sb.append(letterChar.charAt(random.nextInt(letterChar.length()))); } return sb.toString(); } /** * 由小字字母组成的随机字符串 * @param length * @return */ public static String generateLowerString(int length) { return generateMixString(length).toLowerCase(); } /** * 由大写字母组成的随机字符串 * @param length * @return */ public static String generateUpperString(int length) { return generateMixString(length).toUpperCase(); } /** * 产生指字个数的0组成的字符串 * @param length * @return */ public static String generateZeroString(int length) { StringBuffer sb = new StringBuffer(); for (int i = 0; i < length; i++) { sb.append('0'); } return sb.toString(); } /** * 将数字转化成指字长度的字符串 * @param num * @param fixdlenth * @return */ public static String toFixdLengthString(long num, int fixdlenth) { StringBuffer sb = new StringBuffer(); String strNum = String.valueOf(num); if (fixdlenth - strNum.length() >= 0) { sb.append(generateZeroString(fixdlenth - strNum.length())); } else { throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常!"); } sb.append(strNum); return sb.toString(); } /** * 将数字转化成指字长度的字符串 * @param num * @param fixdlenth * @return */ public static String toFixdLengthString(int num, int fixdlenth) { StringBuffer sb = new StringBuffer(); String strNum = String.valueOf(num); if (fixdlenth - strNum.length() >= 0) { sb.append(generateZeroString(fixdlenth - strNum.length())); } else { throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常!"); } sb.append(strNum); return sb.toString(); } /** * 这个方法只支持最大长度为32的随机字符串,如要支持更大长度的,可以适当修改此方法,如前面补、后面补,或者多个uuid相连接 * @param length * @return */ private static String toFixedLengthStringByUUID(int length) { //也可以通过UUID来随机生成 UUID uuid = UUID.randomUUID(); return uuid.toString().replace("-", "").substring(0, length); } public static void main(String[] args) { System.out.println(generateString(32)); System.out.println(generateMixString(32)); System.out.println(generateLowerString(32)); System.out.println(generateUpperString(32)); System.out.println(generateZeroString(32)); System.out.println(toFixdLengthString(123, 32)); System.out.println(toFixdLengthString(123L, 32)); System.out.println(toFixedLengthStringByUUID(32)); } }