检测网络资源是否有效代码,CSharp代码库,德仔网

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【CSharp】检测网络资源是否有效
作者:zhanqi / 发布于2011/7/7/ 748
下载数据时，首先需要知道文件在服务器是否存在或链接是否有效，利用 HTTP 的 HEAD 方法，根据 HTTP 的响应状态码，即可确定该资源的可用性。
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            <td class="content">"csharp keyword"><strong><font color="#006699">public</font></strong> "csharp keyword"><strong><font color="#006699">static</font></strong> "csharp keyword"><strong><font color="#006699">bool</font></strong> "csharp plain">CheckWebResource("csharp keyword"><strong><font color="#006699">string</font></strong> "csharp plain">uriString)</td>
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            <td class="content">"csharp plain">{</td>
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            <td class="content">"csharp keyword"><strong><font color="#006699">try</font></strong></td>
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            <td class="content">"csharp plain">{</td>
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            <td class="content">"csharp comments"><font color="#008200">// URI 必须使用 </font><a href="http:///"><font color="#008200">http://</font></a><font color="#008200"> 或 </font><a href="https:///"><font color="#008200">https://</font></a><font color="#008200"> 开头，否则会 uri 前缀无效或强制转换失败！ </font></td>
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            <td class="content">"csharp plain">HttpWebRequest webReq = (HttpWebRequest)WebRequest.Create(uriString);</td>
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            <td class="content">"csharp plain">webReq.Method = WebRequestMethods.Http.Head;</td>
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            <td class="content">"csharp plain">webReq.Timeout = 3000;</td>
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            <td class="content">"csharp plain">HttpWebResponse webRes = (HttpWebResponse)webReq.GetResponse();</td>
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            <td class="content">"csharp keyword"><strong><font color="#006699">return</font></strong> "csharp plain">webRes.StatusCode == HttpStatusCode.OK;</td>
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            <td class="content">"csharp plain">}</td>
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            <td class="content">"csharp keyword"><strong><font color="#006699">catch</font></strong> "csharp plain">(Exception ex)</td>
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            <td class="content">"csharp plain">{</td>
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            <td class="content">"csharp comments"><font color="#008200">// 输出到控制台</font></td>
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            <td class="content">"csharp plain">System.Diagnostics.Debug.WriteLine(ex.Message);</td>
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            <td class="content">"csharp keyword"><strong><font color="#006699">return</font></strong> "csharp keyword"><strong><font color="#006699">false</font></strong>"csharp plain">;</td>
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            <td class="content">"csharp plain">}</td>
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            <td class="content">"csharp plain">}</td>
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