Java实现获取指定长度随机字符串

思路：使用assic码表，三个范围：数字(48-57)，大写字母(65-90)，小写字母(97-122)

 代码：

import java.util.Random;
 
/**
 * 随机字符串工具
 * 
 * @author volitation
 *
 */
public class RandomString {
 
    /**
     * 获取指定长度随机字符串
     * 
     * @param length
     * @return
     */
    public static String getRandomString(int length) {
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            int number = random.nextInt(3);
            long result = 0;
            switch (number) {
            case 0:
                result = Math.round(Math.random() * 25 + 65);
                sb.append(String.valueOf((char) result));
                break;
            case 1:
                result = Math.round(Math.random() * 25 + 97);
                sb.append(String.valueOf((char) result));
                break;
            case 2:
                sb.append(String.valueOf(new Random().nextInt(10)));
                break;
            }
        }
        return sb.toString();
    }
    
    /**
     * 测试验证
     * 
     * @param args
     */
    public static void main(String[] args) {
        System.out.println(RandomString.getRandomString(5));
        System.out.println(RandomString.getRandomString(10));
        System.out.println(RandomString.getRandomString(15));
    }
 
}

测试：

NVadc
8C1UH1Y0hS
dfiXZMR22pv422I

ASCII码表：