擅长:python、mysql、java
<pre><code>chars=['A', 'B', 'C', 'D', '*']
s=""
L = len(chars)
for i in range(0,5):
s += chars[random.randrange(0,L)]
# now ensure that a character is present by setting a random character
s[random.randrange(0,5)] = chars[random.randrange(0,L-1)]
</code></pre>