Java随机取字符串的工具类

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原文：Java随机取字符串的工具类
源代码下载地址：http://www.zuidaima.com/share/1550463479532544.htm
Java 随机取字符串的工具类可以全部是数字，字符，也可以字符和数字组合的工具类，希望能给大家带来帮助
Java随机取字符串的工具类
package com.zuidaima.test;import java.util.Random;public class RandomUtils {public static final String ALLCHAR = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";public static final String LETTERCHAR = "abcdefghijkllmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";public static final String NUMBERCHAR = "0123456789"; /**      * 返回一个定长的随机字符串(只包含大小写字母、数字)      * @param length 随机字符串长度      * @author www.zuidaima.com     * @return 随机字符串      */ 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();}/**      * 返回一个定长的随机纯字母字符串(只包含大小写字母)      * @param length 随机字符串长度      * @author www.zuidaima.com     * @return 随机字符串      */     public static String generateMixString(int length)    {             StringBuffer sb = new StringBuffer();             Random random = new Random();             for (int i = 0; i < length; i++)            {                     sb.append(ALLCHAR.charAt(random.nextInt(LETTERCHAR.length())));             }             return sb.toString();     }     /**      * 返回一个定长的随机纯大写字母字符串(只包含大小写字母)      *      * @param length 随机字符串长度      * @return 随机字符串      */     public static String generateLowerString(int length) {             return generateMixString(length).toLowerCase();     }     /**      * 返回一个定长的随机纯小写字母字符串(只包含大小写字母)      *      * @param length 随机字符串长度      * @author www.zuidaima.com     * @return 随机字符串      */     public static String generateUpperString(int length) {             return generateMixString(length).toUpperCase();     }     /**      * 生成一个定长的纯0字符串      *      * @param length 字符串长度      * @return 纯0字符串      */     public static String generateZeroString(int length) {             StringBuffer sb = new StringBuffer();             for (int i = 0; i < length; i++) {                     sb.append('0');             }             return sb.toString();     }     /**      * 根据数字生成一个定长的字符串，长度不够前面补0      *      * @param num             数字      * @param fixdlenth 字符串长度      * @author www.zuidaima.com     * @return 定长的字符串      */     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();     }     /**      * 根据数字生成一个定长的字符串，长度不够前面补0      *      * @param num             数字      * @param fixdlenth 字符串长度      * @author www.zuidaima.com     * @return 定长的字符串      */     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();     }         /**     * 每次生成的len位数都不相同     * @param param        * @return 定长的数字     */    public static int getNotSimple(int[] param,int len)    {         Random rand = new Random();         for (int i = param.length; i > 1; i--)         {             int index = rand.nextInt(i);             int tmp = param[index];             param[index] = param[i - 1];             param[i - 1] = tmp;         }         int result = 0;         for(int i = 0; i < len; i++)         {             result = result * 10 + param[i];         }         return result;    }    public static void main(String[] args) {             System.out.println(generateString(10));             System.out.println(generateMixString(10));             System.out.println(generateLowerString(10));             System.out.println(generateUpperString(10));             System.out.println(generateZeroString(10));             System.out.println(toFixdLengthString(123, 10));             System.out.println(toFixdLengthString(123L, 10));             int[] in = {1,2,3,4,5,6,7};            System.out.println(getNotSimple(in,3));    } }
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