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jsowell-common/src/main/java/com/jsowell/common/util/RandomUtil.java

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+package com.jsowell.common.util;
+
+import com.google.common.collect.Lists;
+import com.google.common.collect.Sets;
+
+import java.security.SecureRandom;
+import java.util.List;
+import java.util.Random;
+import java.util.Set;
+
+/**
+ * 获取随机数的工具类
+ */
+public class RandomUtil {
+	private static final String SYMBOLS_NUM = "0123456789"; // 纯数字
+	//如果需加入字母就改成0123456789abcdefg...........
+	private static final String SYMBOLS_NUM_ALPHABET = "abcdefghijklmnopqrstuvwxyz0123456789";
+
+	private static final Random RANDOM = new SecureRandom();
+
+	/**
+	 * 获取6位的短信验证码 纯数字
+	 *
+	 * @return 随机数字
+	 */
+	public static String getSMSVerificationCode() {
+		return getRandomNumber(6);
+	}
+
+	/**
+	 * 获取指定长度随机数
+	 *
+	 * @param length 需要的长度
+	 * @return 随机数
+	 */
+	public static String getRandomNumber(int length) {
+		char[] nonceChars = new char[length];  //指定长度，自己可以设置
+		for (int index = 0; index < nonceChars.length; ++index) {
+			nonceChars[index] = SYMBOLS_NUM.charAt(RANDOM.nextInt(SYMBOLS_NUM.length()));
+		}
+		return new String(nonceChars);
+	}
+
+	/**
+	 * 获取一组不重复的6位数随机数
+	 *
+	 * @param num 数量
+	 * @return
+	 */
+	public static List<String> getRandomNumberList(int num) {
+		List<String> list = Lists.newArrayList();
+		for (int i = 0; i < num; i++) {
+			String code = getNotRepeatCode(list);
+			// System.out.println(code);
+			list.add(code);
+		}
+		return list;
+	}
+
+
+	/**
+	 * 获取一组不重复的6位数随机数
+	 */
+	private static String getNotRepeatCode(List<String> list) {
+		// 获取随机验证码
+		String code = RandomUtil.getSMSVerificationCode();
+		// 判断list中是否存在
+		boolean contains = list.contains(code);
+		if (contains) {
+			// 已经存在，重新获取一个
+			code = getNotRepeatCode(list);
+		}
+		return code;
+	}
+
+
+	public static void main(String[] args) {
+		List<String> randomNumberList = getRandomNumberList(100000);
+		Set<String> set = Sets.newHashSet(randomNumberList);
+		System.out.println("list长度：" + randomNumberList.size());
+		System.out.println("set长度：" + set.size());
+	}
+
+}