我想先执行这个wc_DownloadStringCompleted异步事件再执行retrun。 public string get(string cityName)
{
//获取目标城市的经纬度
string str1 = HttpUtility.UrlEncode(cityName);//更改目的地的数据类型
string str = "http://api.map.baidu.com/geocoder?address=" + str1 + "&key=e99d1a1c866d781a85a0c42799a3182c";//查询目的地经纬度url
WebClient wc = new WebClient();//用WebClient来下载网上的内容,可以是图片或者文档
wc.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);//异步事件开始下载
wc.DownloadStringAsync(new Uri(str));
}
void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{ string str5 = e.Result; //返回网页的XML内容字符串类型
XElement xelement = XElement.Parse(str5);//根据返回的字符串类型加载成XML元素
foreach (XElement item in xelement.Descendants())
{
if (item.Name == "lng")
{
longtude1 = item.Value;//经度
}
if (item.Name == "lat")
{
langtide1 = item.Value;//纬度
}
}
}
{
//获取目标城市的经纬度
string str1 = HttpUtility.UrlEncode(cityName);//更改目的地的数据类型
string str = "http://api.map.baidu.com/geocoder?address=" + str1 + "&key=e99d1a1c866d781a85a0c42799a3182c";//查询目的地经纬度url
WebClient wc = new WebClient();//用WebClient来下载网上的内容,可以是图片或者文档
wc.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);//异步事件开始下载
wc.DownloadStringAsync(new Uri(str));
}
void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{ string str5 = e.Result; //返回网页的XML内容字符串类型
XElement xelement = XElement.Parse(str5);//根据返回的字符串类型加载成XML元素
foreach (XElement item in xelement.Descendants())
{
if (item.Name == "lng")
{
longtude1 = item.Value;//经度
}
if (item.Name == "lat")
{
langtide1 = item.Value;//纬度
}
}
}
wc.DownloadStringCompleted += new DownloadStringCompletedEventHandler(wc_DownloadStringCompleted);//异步事件开始下载
wc.DownloadStringAsync(new Uri(str));完全没用上异步的好处啊,换了吧.
WebClient wc = new WebClient();//
string html = wc.DownloadString(new Uri(str));
wc_DownloadStringCompleted(html);