java 生成随机密码

/**
	 * 生成随机密码
	 * author LiuQiang
	 * date 2013-10-16 上午11:43:17
	 * @return
	 * length 密码长度 
	 * count 特殊字符个数
	 */
	public static String setPass(int length,int count){
		//// 得到8-20 的随机数
		//Random rd = new Random();
		//length = rd.nextInt(20)%(20-8+1) + 8;
		char[] ss = new char[length];
		 int[] flag = {0,0,0}; //A-Z, a-z, 0-9
		 int i=0;
		while(flag[0]==0 || flag[1]==0 || flag[2]==0 || i<length) {
		    i = i%length;
		    int f = (int) (Math.random()*3%3);
		    if(f==0)  
		    	ss[i] = (char) ('A'+Math.random()*26);
		    else if(f==1)  
		    	ss[i] = (char) ('a'+Math.random()*26);
		    else 
		    	ss[i] = (char) ('0'+Math.random()*10);    
		    flag[f]=1;
		    i++;
		 }
		Random rd = new Random();
		char[] a = {'@','#','$','%','&','*'};
		int max = ss.length-1;
		for(int n=0;n<count;n++){
			int indexa = rd.nextInt(5);
			int indexss = rd.nextInt(max);
			ss[indexss]=a[indexa];
		}
		
		return new String(ss);
	}