C#下载歌词文件的同步和异步方法
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前段时间写了一篇C#解析Lrc歌词文件，对lrc文件进行解析，支持多个时间段合并。本文借下载歌词文件来探讨一下同步和异步方法。
{
"count": 2,"code": 0,"result": [
{
"aid": 2727794,"lrc": "http://s.geci.me/lrc/327/32793/3279317.lrc","song": "不得不爱","artist_id": 2,"sid": 3279317
},{
"aid": 3048347,"lrc": "http://s.geci.me/lrc/371/37129/3712941.lrc","sid": 3712941
}
]
}
在C#解析Lrc歌词文件中我们创建了Lrc类，我们继续在该类中添加方法。 同步下载实现
public static Lrc SearchLrc(string musicName)
{
string path = @"D:lrc" + musicName + ".lrc";
if (System.IO.File.Exists(path))
{
return InitLrc(path);
}
else
{
return DownloadLrc(musicName,path);
}
}
下载歌词利用WebClient，首先用DownloadString方法将获取json，再利用JavaScriptSerializer反序列化为自定义对象，这样就得到了lrc文件的url，最后通过url将lrc文件下载到本地，再调用InitLrc方法返回Lrc对象。
public class TempJosnMain
{
public int count { get; set; }
public int code { get; set; }
public List<TempJsonChild> result { get; set; }
}
public class TempJsonChild
{
public int aid { get; set; }
public string lrc { get; set; }
public string song { get; set; }
public int artist_id { get; set; }
public int sid { get; set; }
}
static Lrc DownloadLrc(string musicName,string path)
{
if (musicName.Contains("-"))
musicName = musicName.Split('-')[1].Trim();
string url = "http://geci.me/api/lyric/" + musicName;
WebClient wc = new WebClient();
string json = wc.DownloadString(url);
JavaScriptSerializer js = new JavaScriptSerializer();
TempJosnMain res = js.Deserialize<TempJosnMain>(json);
if (res.count > 0)
{
wc.DownloadFile(new Uri(res.result[0].lrc),path);
wc.Dispose();
return InitLrc(path);
}
return new Lrc();
}
异步下载实现
public static void SearchLrcAsyc(string musicName,Action<Lrc> action)
{
string path = @"D:lrc" + musicName + ".lrc";
if (System.IO.File.Exists(path))
{
action(InitLrc(path));
}
else
{
DownloadLrcAsyc(musicName,path,action);
}
}
WebClient的DownloadStringAsync实现异步下载字符串，不会阻止调用线程。 public void DownloadStringAsync( Uri address,object userToken ) address
public class CallbackObject
{
public string path { get; set; }
public Action<Lrc> action { get; set; }
}
static void DownloadLrcAsyc(string musicName,string path,Action<Lrc> action)
{
if (musicName.Contains("-"))
musicName = musicName.Split('-')[1].Trim();
string url = "http://geci.me/api/lyric/" + musicName;
WebClient wc = new WebClient();
CallbackObject co = new CallbackObject()
{
action = action,path = path
};
wc.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);
wc.DownloadStringAsync(new Uri(url),co);
}
static void wc_DownloadStringCompleted(object sender,DownloadStringCompletedEventArgs e)
{
JavaScriptSerializer js = new JavaScriptSerializer();
TempJosnMain res = js.Deserialize<TempJosnMain>(e.Result);
if (res.count > 0)
{
WebClient wc = sender as WebClient;
if (wc == null)
wc = new WebClient();
CallbackObject co = e.UserState as CallbackObject;
wc.DownloadFileCompleted += new System.ComponentModel.AsyncCompletedEventHandler(wc_DownloadFileCompleted);
wc.DownloadFileAsync(new Uri(res.result[0].lrc),co.path,co);
}
}
static void wc_DownloadFileCompleted(object sender,System.ComponentModel.AsyncCompletedEventArgs e)
{
CallbackObject co = e.UserState as CallbackObject;
co.action(InitLrc(co.path));
}
最后演示：
点击下载时会有线程等待感觉像程序”卡死”,而异步下载则非常流畅。 以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持编程小技巧。 （编辑：李大同） 【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容! |
