src/org/nutz/lang/random/StringGenerator.java
public String next() {
        if (maxLen <= 0 || minLen <= 0 || minLen > maxLen)
            return null;
        char[] buf = new char[R.random(minLen, maxLen)];
        for (int i = 0; i < buf.length; i++)
            buf[i] = CharGenerator.next();
        return new String(buf);
    }
public String next() {
        if (maxLen <= 0 || minLen <= 0 || minLen > maxLen)
            return null;
        char[] buf = new char[R.random(minLen, maxLen)];
        for (int i = 0; i < buf.length; i++)
            buf[i] = CharGenerator.next();
        return new String(buf);
    }
根据设置的max和min的长度,生成随机字符串.
<p/>
若max或min小于0,则返回null

@return 生成的字符串