C#实现下载网页HTML源码的方法

本文实例讲述了c#实现下载网页html源码的方法。分享给大家供大家参考之用。具体方法如下：

public static class download_html
{
private static int failcount = 0; //记录下载失败的次数

public static string gethtml(string url) //传入要下载的网址
{
string str = string.empty;
try
{
system.net.webrequest request = system.net.webrequest.create(url);
request.timeout = 10000; //下载超时时间
request.headers.set("pragma", "no-cache");
system.net.webresponse response = request.getresponse();
system.io.stream streamreceive = response.getresponsestream();
encoding encoding = encoding.getencoding("gb2312");//utf-8 网页文字编码
system.io.streamreader streamreader = new system.io.streamreader(streamreceive, encoding);
str = streamreader.readtoend();
streamreader.close();
}
catch (exception ex)
{
failcount++;

if (failcount > 5)
{
var result = system.windows.forms.messagebox.show("已下载失败" + failcount + "次，是否要继续尝试？" + environment.newline + ex.tostring(), "数据下载异常", system.windows.forms.messageboxbuttons.yesno, system.windows.forms.messageboxicon.error);
if (result == system.windows.forms.dialogresult.yes)
{
str = gethtml(url);
}
else
{
system.windows.forms.messagebox.show("下载html失败" + environment.newline + ex.tostring(), "下载html失败", system.windows.forms.messageboxbuttons.ok, system.windows.forms.messageboxicon.error);
throw ex;
}
}
else
{
str = gethtml(url);
}
}

failcount = 0; //如果能执行到这一步就表示下载终于成功了
return str;
}

希望本文所述对大家的c#程序设计有所帮助