C#下载文件(可显示进度)的方法实现代码,CSharp代码库,德仔网

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【CSharp】 C#下载文件(可显示进度)的方法实现
作者:Dezai.CN / 发布于2012/1/12/ 656
在做WIN FORM程序中经常要使用到升级功能，就需要从服务器上下载最新扔软件程序。如何下载呢？
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<span size="2"><span style="COLOR: #808080" color="#808080">        ///</span><span style="COLOR: #008000"> </span><span style="COLOR: #808080"><summary></span></span><span size="2"><span style="COLOR: #008000">        
        </span><span style="COLOR: #808080">///</span></span><span size="2"><span style="COLOR: #008000"> c#,.net 下载文件        
        </span><span style="COLOR: #808080">///</span><span style="COLOR: #008000"> </span><span style="COLOR: #808080"></summary></span></span><span size="2"><span style="COLOR: #008000">        
        </span><span style="COLOR: #808080">///</span><span style="COLOR: #008000"> </span><span style="COLOR: #808080"><param name="URL"></span><span style="COLOR: #008000">下载文件地址</span><span style="COLOR: #808080"></param></span></span><span size="2"><span style="COLOR: #008000">       </span></span><span size="2"><span style="COLOR: #008000">
        </span><span style="COLOR: #808080">///</span><span style="COLOR: #008000"> </span><span style="COLOR: #808080"><param name="Filename"></span><span style="COLOR: #008000">下载后的存放地址</span><span style="COLOR: #808080"></param></span></span><span size="2"><span style="COLOR: #008000">        
        </span><span style="COLOR: #808080">///</span><span style="COLOR: #008000"> </span><span style="COLOR: #808080"><param name="Prog"></span><span style="COLOR: #008000">用于显示的进度条</span><span style="COLOR: #808080"></param></span></span><span size="2"><span style="COLOR: #008000"> </span></span><span style="COLOR: #808080">
</span><span size="2">        <span style="COLOR: #0000ff">public</span> <span style="COLOR: #0000ff">void</span>  DownloadFile(<span style="COLOR: #0000ff">string</span> URL, <span style="COLOR: #0000ff">string</span></span><span size="2"> filename, System.Windows.Forms.ProgressBar prog,  System.Windows.Forms.Label label1)
         {</span>
<span size="2">            <span style="COLOR: #0000ff" color="#0000ff">float</span> percent = 0;
            <span style="COLOR: #0000ff">try</span></span>
<span size="2">             {
                 System.Net.HttpWebRequest Myrq  </span><span size="2">=</span><span size="2">  (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(URL);
                  System.Net.HttpWebResponse myrp =</span><span size="2">  (System.Net.HttpWebResponse)Myrq.GetResponse();
                <span style="COLOR: #0000ff">long</span> totalBytes  =</span><span size="2"> myrp.ContentLength;
                <span style="COLOR: #0000ff">if</span> (prog != <span style="COLOR: #0000ff">null</span></span><span size="2">)
                 {
                      prog.Maximum = (<span style="COLOR: #0000ff">int</span></span><span size="2">)totalBytes;
                 }
                  System.IO.Stream st =</span><span size="2">  myrp.GetResponseStream();
                 System.IO.Stream so = <span style="COLOR: #0000ff">new</span></span><span size="2"> System.IO.FileStream(filename,  System.IO.FileMode.Create);
                <span style="COLOR: #0000ff">long</span>  totalDownloadedByte = <span style="COLOR: #800080">0</span></span><span size="2">;
                <span style="COLOR: #0000ff">byte</span>[] by  =  <span style="COLOR: #0000ff">new</span>  <span style="COLOR: #0000ff">byte</span>[<span style="COLOR: #800080">1024</span></span><span size="2">];
                <span style="COLOR: #0000ff">int</span> osize  =  st.Read(by, <span style="COLOR: #800080">0</span>, (<span style="COLOR: #0000ff">int</span></span><span size="2">)by.Length);
                <span style="COLOR: #0000ff">while</span> (osize  >  <span style="COLOR: #800080">0</span></span><span size="2">)
                 {
                      totalDownloadedByte = osize +</span><span size="2"> totalDownloadedByte;
                      System.Windows.Forms.Application.DoEvents();
                      so.Write(by, <span style="COLOR: #800080">0</span></span><span size="2">,  osize);
                    <span style="COLOR: #0000ff">if</span> (prog != <span style="COLOR: #0000ff">null</span></span><span size="2">)
                     {
                          prog.Value = (<span style="COLOR: #0000ff">int</span></span><span size="2">)totalDownloadedByte;
                      }
                     osize = st.Read(by,  <span style="COLOR: #800080">0</span>,  (<span style="COLOR: #0000ff">int</span></span><span size="2">)by.Length);</span>
<span size="2">                     percent = (float)totalDownloadedByte  / (float)totalBytes * 100;
                     label1.Text = "当前补丁下载进度" +  percent.ToString() + "%";
                   <span style="COLOR: #333300"> </span><span color="#ff0000"> System.Windows.Forms.Application.DoEvents();  //必须加注这句代码，否则label1将因为循环执行太快而来不及显示信息
</span>                 }
                  so.Close();
                 st.Close();
              }
            <span style="COLOR: #0000ff">catch</span></span><span size="2"> (System.Exception)
              {
                <span style="COLOR: #0000ff">throw</span></span><span size="2">;
             }
         }</span>
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