简单实用的随机数生成方式

分享一个项目中简单的随机数生成方法，简单实用。

import java.util.Random;

@SuppressWarnings("unused")
public class RandomCreator {

	/**
	 * 生成随机数种类
	 */

	private static final String NUMBER = "0123456789";
	private static final String LOWERCASE = "abcdefghijklmnopqrstuvwxyz";
	private static final String UPPERCASE = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	private static final String NUMBER_LOWERCASE = "0a1b2c3d4e5f6g7h8i9jklmnopqrstuvwxyz";
	private static final String NUMBER_UPPERCASE = "0A1B2C3D4E5F6G7H8I9JKLMNOPQRSTUVWXYZ";
	private static final String NUMBER_LOWER_AND_UPPERCASE = "0Aa1Bb2Cc3Dd4Ee5Ff6Gg7Hh8Ii9JjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz";

	/**
	 * 根据方式，和长度获取随即数
	 * @param type
	 * @param length
	 * @return
	 */
	public static String getRandom(String type,int length){
		//返回的随机数对象
		StringBuffer randomString = new StringBuffer();
		Random random = new Random();
		//模式的长度
		int typeLength = type.length();
		for (int i = 0; i < length; i++) {
			int index = random.nextInt(typeLength);
			randomString.append(type.substring(index,index+1));
		}
		return randomString.toString();
	}


	public static void main(String[] args) {
		System.out.println(getRandom(RandomCreator.LOWERCASE, 10));
		System.out.println(getRandom(RandomCreator.NUMBER, 10));
		System.out.println(getRandom(RandomCreator.NUMBER_LOWERCASE, 10));
		System.out.println(getRandom(RandomCreator.NUMBER_UPPERCASE, 10));
		System.out.println(getRandom(RandomCreator.UPPERCASE, 10));
          System.out.println(getRandom(RandomCreator.NUMBER_LOWER_AND_UPPERCASE, 10));
	}
}