.net core不支持gb2312编码的问题

在用net core写爬虫的时候，发现默认不再支持gb2312编码了：

解决方案如下：

1，引入System.Text.Encoding.CodePages：

2，在需要的地方注册EncodingProvider的方法；

3，调用 Encoding.GetEncoding("GB2312").GetString(pageSource);

public void CityCrawler(string allCityUrl)
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
            var cityList = new List<string>();
            var pageSource = new HttpClient(new HttpClientHandler { AutomaticDecompression = DecompressionMethods.GZip })
                    .GetByteArrayAsync(allCityUrl).Result;
            var result = Encoding.GetEncoding("GB2312").GetString(pageSource);

            var cities = Regex.Matches(result,
                "([u4e00-u9fa5]{2,5})", "spell": "[A-Za-z]+", "url": "//([A-Za-z]{2,}.esf.fang.com)");
            for (int index = 0; index < cities.Count; index++)
            {
                var city = cities[index].Groups[1].Value + ":" + "https://" + cities[index].Groups[2].Value;
                cityList.Add(city);
            }
            File.WriteAllLines("房天下城市列表.txt", cityList);
        }