用Java(8) 随机生成一一个指定长度及参数要求的验证码。参数有:是否包含数字、是否包含小写字母、是否包含大写字母、是否允许验证码有重复字符出现。 *随机生成--个指定长度及参数要求的验证码* @param len验证码长度 * @param isDigit 是否包含数字 * @param isl owerCase是否包含小写字母* @param isUpperCase是否包含大写字母* @param isRepeat是否允许验证码有重复字符出现 * @return验证码 public static String getCode(int len,booleanisDigit,boolean isL owerCase,boolean isUpperCase,boolean isRepeat)

好的，以下是用Java(8)随机生成指定长度及参数要求的验证码的代码：

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class VerificationCodeGenerator {
    private static final String DIGITS = "0123456789";
    private static final String LOWER_CASE_LETTERS = "abcdefghijklmnopqrstuvwxyz";
    private static final String UPPER_CASE_LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    public static String getCode(int len, boolean isDigit, boolean isLowerCase, boolean isUpperCase, boolean isRepeat) {
        if (!isDigit && !isLowerCase && !isUpperCase) {
            throw new IllegalArgumentException("At least one of isDigit, isLowerCase and isUpperCase must be true");
        }
        if (len <= 0) {
            throw new IllegalArgumentException("len must be greater than 0");
        }
        Random random = new Random();
        List<Character> chars = new ArrayList<>();
        if (isDigit) {
            for (int i = 0; i < DIGITS.length(); i++) {
                chars.add(DIGITS.charAt(i));
            }
        }
        if (isLowerCase) {
            for (int i = 0; i < LOWER_CASE_LETTERS.length(); i++) {
                chars.add(LOWER_CASE_LETTERS.charAt(i));
            }
        }
        if (isUpperCase) {
            for (int i = 0; i < UPPER_CASE_LETTERS.length(); i++) {
                chars.add(UPPER_CASE_LETTERS.charAt(i));
            }
        }
        if (!isRepeat && chars.size() < len) {
            throw new IllegalArgumentException("Not enough characters to generate a unique code");
        }
        StringBuilder codeBuilder = new StringBuilder(len);
        for (int i = 0; i < len; i++) {
            int index = random.nextInt(chars.size());
            codeBuilder.append(chars.get(index));
            if (!isRepeat) {
                chars.remove(index);
            }
        }
        return codeBuilder.toString();
    }
}

调用方式示例:

String code = VerificationCodeGenerator.getCode(6, true, true, true, false);
System.out.println(code);

该示例调用方法生成一个长度为6的验证码，它包含数字、小写字母和大写字母，但不允许有重复字符出现。