去除截取网页编码字段中所包含的字母和标点及空格测试，目的是减少干扰，以编码方式能跟准确的识别编码方式。（utf-8，gbk）-Remove the intercept web page code field contained in the letters and punctuation and Spaces test, purpose is to reduce the interference, to encode method can accurately identify the encoding. (utf-8, GBK)