Java随机生成8位密码

密码规则：8位+大写字母+小写字母+特殊字符

String password = "12345678";
int[] pwdindex = {0,1,2,3,4,5,6,7};

char[] specialCharacters = {'@','#','.','!','$'};

 char[] numbers = { '0','1','2','3','4','5','6','7','8','9'};
 
 char[] upperLetters = {'A','B','C','D','E','F','G','H','I','J',
		 'K','L','M','N','O','P','Q','R','S','T',
		 'U','V','W','X','Y','Z'};
 
 char[] lowerLetters = {'a','b','c','d',
		  'e','f','g','h','i','j','k','l','m','n',
		 'o','p','q','r','s','t','u','v','w','x',
		 'y','z'};
 
 
 char[] allCharacters = { '0','1','2','3','4','5','6','7','8','9',
		  'A','B','C','D','E','F','G','H','I','J',
		  'K','L','M','N','O','P','Q','R','S','T',
		  'U','V','W','X','Y','Z','a','b','c','d',
		 'e','f','g','h','i','j','k','l','m','n',
		 'o','p','q','r','s','t','u','v','w','x',
		  'y','z'};
 
 
 //1. 随机生成特殊字符，随机 放到密码2-7位置中(特殊字符不出现在开头或结尾)
 //System.out.println("随机生成特殊字符，随机 放到密码2-7位置中");
 int aindex = new Random().nextInt(5);
 //System.out.println(specialCharacters[aindex]);
 int aposition = new Random().nextInt(6)+1;
 //System.out.println(password.charAt(aposition));
 password = password.replace(password.charAt(aposition), specialCharacters[aindex]);
 //System.out.println(password);
 
 //2. 随机生成数据，随机放到1-8位置中（除去第1步占用的位置）
int bindex = new Random().nextInt(10);
//System.out.println(numbers[bindex]);
 int bposition = 0;
 do{
	 bposition = new Random().nextInt(8);
 }while(bposition==aposition);
 //System.out.println(password.charAt(bposition));
 password = password.replace(password.charAt(bposition), numbers[bindex]);
 //System.out.println(password);

//3. 随机生成大写字母，随机放到1-8位置中（除去第1、2步占用的位置）
int cindex = new Random().nextInt(26);
//System.out.println(upperLetters[cindex]);
int cposition = 0;
 do{
	 cposition = new Random().nextInt(8);
 }while(cposition==aposition||cposition==bposition);
 //System.out.println(password.charAt(bposition));
 password = password.replace(password.charAt(cposition), upperLetters[cindex]);
// System.out.println(password);

//4. 随机生成小写字母，随机放到1-8位置中（除去第1、2、3步占用的位置）
int dindex = new Random().nextInt(26);
//System.out.println(lowerLetters[dindex]);
int dposition = 0;
 do{
	 dposition = new Random().nextInt(8);
 }while(dposition==aposition||dposition==cposition||dposition==bposition);
 //System.out.println(password.charAt(bposition));
 password = password.replace(password.charAt(dposition), lowerLetters[dindex]);
 //System.out.println(password);

//前4步保证密码包含（特殊字符&大写字母&小写字母&数字  且位置是随机的）
//5. 随机生成数字大小写字母，随机放到1-8位置中（除去第1、2、3、4步占用的位置，余下四位）
 for (int i = 0; i < pwdindex.length; i++) {
	if(pwdindex[i]!=aposition&&pwdindex[i]!=bposition
			&&pwdindex[i]!=cposition&&pwdindex[i]!=dposition){
		int eindex = new Random().nextInt(62);
		password = password.replace(password.charAt(pwdindex[i]), allCharacters[eindex]);
	}
}
System.out.println(password);