java 生成 序列号 随机字符串等

private static int maxvaluefive=99999999;
private static int minvaluefive=0;
private static AtomicInteger atomic = new AtomicInteger(minvaluefive);
/**  生成序列号 */
static String getSeqFive(int coverPad) {
for (;;) {
int current = atomic.get();
int newValue = current >= maxvaluefive ? minvaluefive : current + 1;
if (atomic.compareAndSet(current, newValue)) {
return StringUtils.leftPad(String.valueOf(current), coverPad, "0");
}
}
}

private static Random strGen = new Random();;
private static Random numGen = new Random();;
private static char[] numbersAndLetters = ("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ").toCharArray();;
private static char[] numbers = ("0123456789").toCharArray();;
/** * 产生随机字符串 * */
public static final String randomString(int length) {
if (length < 1) {
return null;
}
char[] randBuffer = new char[length];
for (int i = 0; i < randBuffer.length; i++) {
randBuffer[i] = numbersAndLetters[strGen.nextInt(61)];
}
return new String(randBuffer);
}

/** * 产生随机数值字符串 * */
public static final String randomNumStr(int length) {
if (length < 1) {
return null;
}
char[] randBuffer = new char[length];
for (int i = 0; i < randBuffer.length; i++) {
randBuffer[i] = numbers[numGen.nextInt(9)];
}
return new String(randBuffer);
}