java做个密码生成器，嘿嘿

package j_bin;

import java.util.Random;

public class pwdGen {

    private Random rdseed = new Random();

        /*
     *@param
     *length        password length;
     *@param
     *letters       boolean non-capital letters combination control;
     *@param
     *letters_capi  boolean capital letters combination control;
     *@param
     *numbers       numbers control;
     */
    public String getpwd(int length, boolean letters, boolean letters_capi, boolean numbers) {
        StringBuilder sb = new StringBuilder();
        Random rd = this.rdseed;
        while (length-- > 0) {
            char _1dgt = 0;
            if (letters && letters_capi && numbers) {
                int _key = rd.nextInt(3);
                if (2 == _key) {
                    _1dgt = get_L();
                } else if (1 == _key) {
                    _1dgt = get_L_C();
                } else if (0 == _key) {
                    _1dgt = get_N();
                }
            } else if (letters && letters_capi && !numbers) {
                int _key = rd.nextInt(2);
                if (1 == _key) {
                    _1dgt = get_L();
                } else if (0 == _key) {
                    _1dgt = get_L_C();
                }
            } else if (!letters && letters_capi && numbers) {
                int _key = rd.nextInt(2);
                if (1 == _key) {
                    _1dgt = get_N();
                } else if (0 == _key) {
                    _1dgt = get_L_C();
                }
            } else if (letters && !letters_capi && numbers) {
                int _key = rd.nextInt(2);
                if (1 == _key) {
                    _1dgt = get_L();
                } else if (0 == _key) {
                    _1dgt = get_N();
                }
            } else if (letters && !letters_capi && !numbers) {
                _1dgt = get_L();
            } else if (!letters && !letters_capi && numbers) {
                _1dgt = get_N();
            } else if (!letters && letters_capi && !numbers) {
                _1dgt = get_L_C();
            } else {
                break;
            }

            sb.append(_1dgt);
        }
        return sb.toString();
    }

    private char get_L_C() {
        Random rd = this.rdseed;
        int _dgt = (rd.nextInt(26) + 65);
        return (char) _dgt;
    }

    private char get_N() {
        Random rd = this.rdseed;
        int _dgt = (rd.nextInt(10) + 48);
        return (char) _dgt;
    }

    private char get_L() {
        Random rd = this.rdseed;
        int _dgt = (rd.nextInt(26) + 97);
        return (char) _dgt;
    }

    public static void main(String[] args) {
        pwdGen test = new pwdGen();

        int testct = 100;//测试次数

        long start = System.nanoTime();
        while (testct-- > 0) {
            test.getpwd(10, true, true, true);
        }
        long end = System.nanoTime();
      //  System.out.println(((double) (end - start)) / (1000000000));
        System.out.println(end-start);
      System.out.println(test.getpwd(30, true, true, true));
    }

}