获取Bing每日一图作为登陆背景图片

　　之前使用 幻杀博客提供的必应每日图片API作为网站后台登陆页面的背景图片，一直都很稳定，但今天一大早过来 发现获取不到背景图片了，去到幻杀博客看到挂上了一个公告，因为流量使用的问题，到下月为止API使用不了。这一下，我就懵逼了，之前想偷下懒，反正也在开发阶段，没必要自己写，现在API使用不了了，咋办？没办法只有自己写了。

　　整理下思路：进入登陆界面时，判断下是否有存在今天的图片；如果存在直接返回今天的图片地址给前台；不存在 则异步去下载当天图片，同时向前推十天，一天天检查是否存在图片，存在就立刻返回此图片路径，都没有就返回默认图片路径。

 1 private string GetWallpaper()
 2         {
 3             string wallPath = System.Web.Hosting.HostingEnvironment.MapPath("~/") + "wallpaper\\";
 4             string wall = "/wallpaper/20160715.jpg";
 5             string temp = wallPath + DateTime.Now.ToString("yyyyMMdd") + ".jpg";
 6             if (System.IO.File.Exists(temp))
 7             {
 8                 wall = "/wallpaper/" + DateTime.Now.ToString("yyyyMMdd") + ".jpg";
 9             }
10             else
11             {
12                 //异步开始下载bing图片
13                 TaskDelegat downloadWall = Task;
14                 IAsyncResult asyncResult = downloadWall.BeginInvoke(temp, null, null);
15                 asyncResult.AsyncWaitHandle.WaitOne(0);
16 
17                 for (int i = 1; i <= 11; i++)
18                 {
19                     temp = wallPath + DateTime.Now.AddDays(0 - i).ToString("yyyyMMdd") + ".jpg";
20                     if (System.IO.File.Exists(temp))
21                     {
22                         wall = "/wallpaper/" + DateTime.Now.AddDays(0 - i).ToString("yyyyMMdd") + ".jpg";
23                         break;
24                     }
25                 }
26             }
27             return wall;
28         }

获取背景图路径

 1 private delegate void TaskDelegat(string path);
 2         private static void Task(string path)
 3         {
 4             try {
 5                 string json = string.Empty;
 6                 //请求bing壁纸链接
 7                 using (var webclient = new WebClient())
 8                 {
 9                     json = webclient.DownloadString("http://cn.bing.com/HPImageArchive.aspx?format=js&idx=0&n=1");
10                 }
11                 Regex urlreg = new Regex(@"http://.*?.jpg");
12                 string url = "";
13                 foreach (Match mch in urlreg.Matches(json))
14                 {
15                     url = mch.Value.Trim();
16                 }
17                 if (!string.IsNullOrEmpty(url))
18                 {
19                     HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
20                     req.UserAgent = "Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/31.0.1650.57 Safari/537.36";
21                     req.Headers.Add("Accept-Encoding", "gzip");
22                     WebResponse res = req.GetResponse();
23                     Stream resStream = res.GetResponseStream();
24                     int count = (int)res.ContentLength;
25                     int offset = 0;
26                     byte[] buf = new byte[count];
27                     while (count > 0)
28                     {
29                         int n = resStream.Read(buf, offset, count);
30                         if (n == 0) break;
31                         count -= n;
32                         offset += n;
33                     }
34                     FileStream fs = new FileStream(path, FileMode.Create, FileAccess.Write);
35                     fs.Write(buf, 0, buf.Length);
36                     fs.Flush();
37                     fs.Close();
38                 }
39             }
40             catch(Exception ex)
41             {
42                 throw ex;
43             }
44         }

异步下载Bing每日一图

转载于:https://www.cnblogs.com/tanq/p/5674578.html