生成定长随机数-可做3des密钥

package test;

import java.util.Random;

public class ThreeDes_key {

    public static final String ALLCHAR = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    public static final String LETTERCHAR = "abcdefghijkllmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    public static final String NUMBERCHAR = "0123456789";

    /** 
     * 返回一个定长的带因子的固定的随机字符串(只包含大小写字母、数字)
     *  
     * @param length 
     *            随机字符串长度 
     * @return 随机字符串 
     */
    public static String generateStringByKey(int length, int channel) {
        StringBuffer sb = new StringBuffer();
        Random random = new Random(channel);
        for (int i = 0; i < length; i++) {
            sb.append(ALLCHAR.charAt(random.nextInt(ALLCHAR.length())));
        }
        return sb.toString();
    }

    /** 
     * 返回一个定长的随机字符串(只包含大小写字母、数字)
     *  
     * @param length 
     *            随机字符串长度 
     * @return 随机字符串 
     */
    public static String generateString(int length) {
        StringBuffer sb = new StringBuffer();
        Random random = new Random();
        for (int i = 0; i < length; i++) {
            sb.append(ALLCHAR.charAt(random.nextInt(ALLCHAR.length())));
        }
        return sb.toString();
    }

    /** 
     * 返回一个定长的随机纯字母字符串(只包含大小写字母) 
     *  
     * @param length 
     *            随机字符串长度 
     * @return 随机字符串 
     */
    public static String generateMixString(int length) {
        StringBuffer sb = new StringBuffer();
        Random random = new Random();
        for (int i = 0; i < length; i++) {
            sb.append(ALLCHAR.charAt(random.nextInt(LETTERCHAR.length())));
        }
        return sb.toString();
    }

    /** 
     * 返回一个定长的随机纯大写字母字符串(只包含大小写字母) 
     *  
     * @param length 
     *            随机字符串长度 
     * @return 随机字符串 
     */
    public static String generateLowerString(int length) {
        return generateMixString(length).toLowerCase();
    }

    /** 
     * 返回一个定长的随机纯小写字母字符串(只包含大小写字母) 
     *  
     * @param length 
     *            随机字符串长度 
     * @return 随机字符串 
     */
    public static String generateUpperString(int length) {
        return generateMixString(length).toUpperCase();
    }

    /** 
     * 生成一个定长的纯0字符串 
     *  
     * @param length 
     *            字符串长度 
     * @return 纯0字符串 
     */
    public static String generateZeroString(int length) {
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            sb.append(‘0‘);
        }
        return sb.toString();
    }

    /** 
     * 根据数字生成一个定长的字符串，长度不够前面补0 
     *  
     * @param num 
     *            数字 
     * @param fixdlenth 
     *            字符串长度 
     * @return 定长的字符串 
     */
    public static String toFixdLengthString(long num, int fixdlenth) {
        StringBuffer sb = new StringBuffer();
        String strNum = String.valueOf(num);
        if (fixdlenth - strNum.length() >= 0) {
            sb.append(generateZeroString(fixdlenth - strNum.length()));
        } else {
            throw new RuntimeException("将数字" + num + "转化为长度为" + fixdlenth + "的字符串发生异常！");
        }
        sb.append(strNum);
        return sb.toString();
    }

    /** 
     * 每次生成的len位数都不相同 
     *  
     * @param param 
     * @return 定长的数字 
     */
    public static int getNotSimple(int[] param, int len) {
        Random rand = new Random();
        for (int i = param.length; i > 1; i--) {
            int index = rand.nextInt(i);
            int tmp = param[index];
            param[index] = param[i - 1];
            param[i - 1] = tmp;
        }
        int result = 0;
        for (int i = 0; i < len; i++) {
            result = result * 10 + param[i];
        }
        return result;
    }

    public static void main(String[] args) {
        int channel = 222222;// 测试因子比生产因子少1
        System.out.println("返回一个定长的带因子的固定的随机字符串(只包含大小写字母、数字):" + generateStringByKey(32, channel));
        System.out.println("返回一个定长的随机字符串(只包含大小写字母、数字):" + generateString(32));
        System.out.println("返回一个定长的随机纯字母字符串(只包含大小写字母):" + generateMixString(10));
        System.out.println("返回一个定长的随机纯大写字母字符串(只包含大小写字母):" + generateLowerString(10));
        System.out.println("返回一个定长的随机纯小写字母字符串(只包含大小写字母):" + generateUpperString(10));
        System.out.println("生成一个定长的纯0字符串:" + generateZeroString(10));
        System.out.println("根据数字生成一个定长的字符串，长度不够前面补0:" + toFixdLengthString(123, 10));
        int[] in = { 1, 2, 3, 4, 5, 6, 7 };
        System.out.println("每次生成的len位数都不相同:" + getNotSimple(in, 3));
    }
}