生成随机数字或字母码

public static void GenerateRandomStr() {
String randStr = "ABCDEFGHIabcdef0123456789"; //写入你所希望的所有的字母A-Z,a-z,0-9
StringBuffer generateRandStr=new StringBuffer();
Random rand = new Random();
int randStrLength = 5; //你想生成的随机数的长度
for (int i = 0; i < randStrLength; i++) {
int randNum = rand.nextInt(25);
generateRandStr.append(randStr.substring(randNum,randNum+1));
}
System.out.println(generateRandStr); //打印你的结果
}

//自己写一段代码

public static String getStrOfNum(int num, int strLength)
{
String returnStr =String.valueOf(num);
while(returnStr.length()<strLength)
{
returnStr = "0"+returnStr;
}
return returnStr;
}