生成固定长度的随机字符和数字

/**
* 生成固定长度的随机字符和数字
* @param len
* @return
*/

public static String GetRandomCharAndNumber(int len) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i <len; i++) {
int intRand = (int) (Math.random() * 52);
int numValue = (int) (Math.random() * 10);
char base = (intRand < 26) ? 'A' : 'a';
char c = (char) (base + intRand % 26);
if(numValue%2==0){
sb.append(c);
}else{
sb.append(numValue);
}
}
return sb.toString();
}