如何有效地在Java中生成安全的随机字母数字字符串？

Question

如何有效地在Java中生成安全的随机(或伪随机)字母数字字符串？

Answer 1

初始化包含所有接受的字符(CHARS_ARRAY)的数组,然后实例化SecureRandom实例,并nextInt(CHARS_ARRAY.length)重复调用以获取char数组中的随机索引.将每个字符附加到a,StringBuilder直到获得预期的字符数.

Answer 2

如果您使用Apache Commons Lang，最简单的方法是

RandomStringUtils.random(20, 0, 0, true, true, null, new SecureRandom());

Answer 3

这是重复问题中我的代码的略微修改版本。

public final class RandomString
{

  /* Assign a string that contains the set of characters you allow. */
  private static final String symbols = "ABCDEFGJKLMNPRSTUVWXYZ0123456789"; 

  private final Random random = new SecureRandom();

  private final char[] buf;

  public RandomString(int length)
  {
    if (length < 1)
      throw new IllegalArgumentException("length < 1: " + length);
    buf = new char[length];
  }

  public String nextString()
  {
    for (int idx = 0; idx < buf.length; ++idx) 
      buf[idx] = symbols.charAt(random.nextInt(symbols.length()));
    return new String(buf);
  }

}

Answer 4

    String chrs = "0123456789abcdefghijklmnopqrstuvwxyz-_ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    SecureRandom secureRandom = SecureRandom.getInstanceStrong();
    // 9 is the length of the string you want
    String customTag = secureRandom.ints(9, 0, chrs.length()).mapToObj(i -> chrs.charAt(i))
      .collect(StringBuilder::new, StringBuilder::append, StringBuilder::append).toString();
    System.out.println(customTag);

例子：

// q3HX6EctP
// WjRrMjQT4
// sX-Piq4DB

Answer 5

使用UUID：

UUID random = UUID.randomUUID();
System.out.println( random );