java获取随机数

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<span style="font-size:24px;">package com.jm.util;import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;import java.util.ArrayList;import java.util.List;import java.util.Random;import Decoder.BASE64Encoder;import com.jm.bean.JmAward;public class RandomUtil {/** * 获取从a至z，长度为length随机数 * @return */public static String getRandomStr(int length){String base="abcdefghijklmnopqrstuvwxyz";Random random = new Random();       StringBuffer sb = new StringBuffer();       for (int i = 0; i < length; i++) {           int number = random.nextInt(base.length());           sb.append(base.charAt(number));       }       return sb.toString();   }/** * 获取范围内int值 * @param 获取范围内int值 * @return */public static int getRandomRange(int max,int min){return (int)(Math.random()*(max-min)+min);}/** * 获取随机长度随机字符 * @param length base * @return */public static String getRandomString(int length,String base) { //length表示生成字符串的长度    Random random = new Random();       StringBuffer sb = new StringBuffer();       for (int i = 0; i < length; i++) {           int number = random.nextInt(base.length());           sb.append(base.charAt(number));       }       return sb.toString();    }  /** * 获取随机长度随机字符 * @param length * @return */public static String getRandomString(int length) { //length表示生成字符串的长度    String base = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";       Random random = new Random();       StringBuffer sb = new StringBuffer();       for (int i = 0; i < length; i++) {           int number = random.nextInt(base.length());           sb.append(base.charAt(number));       }       return sb.toString();    }  /** * 获取随机长度随机数字 * @param length * @return */public static String getRandomNumString(int length) { //length表示生成字符串的长度    String base = "0123456789";       Random random = new Random();       StringBuffer sb = new StringBuffer();       for (int i = 0; i < length; i++) {           int number = random.nextInt(base.length());           sb.append(base.charAt(number));       }       return sb.toString();    }  /** * 返回随机数组 * @param start 开始值 * @param end  结束值 * @return */public static int[] getRangRandom(int start, int end) {return getRangRandom(start, end, end - start + 1);}/** * 返回指定范围指定个数的不重复随机数。 * @param start * @param end * @param num * @return */public static int[] getRangRandom(int start, int end, int num) {int length = end - start + 1;//参数不合法if (length < 1 || num > length) {return null;}else {int[] numbers = new int[length];int[] result = new int[num];//循环赋初始值for (int i = 0; i < length; i ++) {numbers[i] = i + start;}Random random = new Random();//取randomMax次数for (int i = 0; i < num; i ++) {//随机获取取数的位置int m = random.nextInt(length - i) + i;result[i] = numbers[m];//交换位置int temp = numbers[m];numbers[m] = numbers[i];numbers[i] = temp;}return result;}}}</span>
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