給 string 添加一個 GetInputStream 擴展方法
有時候,我們須要讀取一些數據,而無論這數據來源於磁盤上的數據文件,還是來源於網絡上的數據。於是。就有了以下的 StringExtensions.cs:
1 using System; 2 using System.IO; 3 using System.Net; 4 5 namespace Skyiv 6 { 7 public static class StringExtensions 8 { 9 public static Stream GetInputStream(this string fileNameOrUri, string user = null, string password = null) 10 { 11 if (!Uri.IsWellFormedUriString(fileNameOrUri, UriKind.Absolute)) return File.OpenRead(fileNameOrUri); 12 var uri = new Uri(fileNameOrUri); 13 if (uri.Scheme == Uri.UriSchemeHttp || uri.Scheme == Uri.UriSchemeHttps) return uri.GetHttpStream(); 14if (uri.Scheme == Uri.UriSchemeFtp) return uri.GetFtpStream(user, password); 15 if (uri.Scheme == Uri.UriSchemeFile) return uri.GetFileStream(); 16 throw new NotSupportedException("Notsupported uri scheme: " + uri.Scheme); 17 } 18 19 static Stream GetFtpStream(this Uri uri, stringuser = null, string password = null) 20 { 21 var ftp = (FtpWebRequest)WebRequest.Create(uri); 22 if (user != null && user != "anonymous" && user != "ftp") 23 ftp.Credentials = new NetworkCredential(user, password); 24 ftp.Method = WebRequestMethods.Ftp.DownloadFile; 25 return ((FtpWebResponse)ftp.GetResponse()).GetResponseStream(); 26 } 27 28 static Stream GetHttpStream(this Uri uri) 29 { 30 return ((HttpWebResponse)((HttpWebRequest)WebRequest.Create(uri)).GetResponse()).GetResponseStream(); 31 } 32 33 static Stream GetFileStream(this Uri uri) 34 { 35 return ((FileWebResponse)((FileWebRequest)WebRequest.Create(uri)).GetResponse()).GetResponseStream(); 36 } 37 } 38 }
上述程序中:
- 第 9 到 17 行的 GetInputStream 擴展方法返回來讀取的數據的輸入流。
- 第 11 行調用 Uri 類的靜態方法 IsWellFormedUriString 推斷是否從網絡上讀取數據。如不是。則直接調用 File 類的靜態方法 OpenRead 得到輸入流。
- 第 12 行構造一個 Uri 類的實例。
- 第 13 行處理輸入使用 http 或者 https 協議的情況。
- 第 14 行處理輸入使用 ftp 協議的情況。
- 第 15 行處理輸入使用 file 協議的情況。
- 第 16 行處理其它協議。就是直接拋出一個 NotSupportedException 異常。表示我們僅僅支持上述四種協議。
- 第 19 到 26 行的 GetFtpStream 擴展方法用於獲得 FTP server上發送的響應數據的輸入流。能夠是匿名的。也能夠是非匿名的。
- 第 28 到 31 行的 GetHttpStream 擴展方法用於獲得使用 http 或者 https 協議的網絡流。
- 第 33 到 36 行的 GetFileStream 擴展方法用於獲得使用 file 協議的本地磁盤文件系統的數據流。
以下就是測試用的 CopyTester.cs:
1 using System.IO; 2 3 namespace Skyiv.Test 4 { 5 static class CopyTester 6 { 7 static void Main(string[] args) 8 { 9 args[0].GetInputStream().CopyTo(File.Create(args[1])); 10 } 11 } 12 }
這個測試程序的功能就是拷貝數據,須要兩個命令行參數:
- 第一個命令行參數指定數據來源,能夠是本地磁盤文件。也能夠是網絡數據,支持 https、http、ftp 和 file 協議,當然,file 協議實際上還是讀取本地磁盤文件。
- 第二個命令行參數指定將要復制到的本地磁盤文件的名稱。
上述測試程序實質內容就是第 9 行的語句:
- 使用第一個命令行參數 args[0] 調用 String 類的 GetInputStream 擴展方法得到輸入流。
- 調用 Stream 類的 CopyTo 方法將輸入流復制到輸出流。
- 輸出流是使用 File 類的靜態方法 Create 得到的。
在 Windows 操作系統中編譯和執行:
E:\work> csc CopyTester.cs StringExtensions.cs Microsoft(R) Visual C# 2010 編譯器 4.0.30319.1 版 版權全部(C) Microsoft Corporation。保留全部權利。 E:\work> CopyTester https://github.com/mono/xsp/zipball/master mono-xsp.zip E:\work> CopyTester http://mysql.ntu.edu.tw/Downloads/Connector-Net/mysql-connector-net-6.5.4-noinstall.zip mysql-connector.zip E:\work> CopyTester ftp://ftp.ntu.edu.tw/pub/MySQL/Downloads/Connector-Net/mysql-connector-net-6.5.4-noinstall.zip mysql-connector.2.zip E:\work> CopyTester file:///E:/work/mysql-connector.zip mysql-connector.3.zip E:\work> CopyTester mysql-connector.zip mysql-connector.4.zip E:\work> dir *.zip 2012/03/11 09:35 468,024 mono-xsp.zip 2012/03/11 09:37 4,176,361 mysql-connector.2.zip 2012/03/11 09:38 4,176,361 mysql-connector.3.zip 2012/03/11 09:38 4,176,361 mysql-connector.4.zip 2012/03/11 09:36 4,176,361 mysql-connector.zip
上面分別測試了以 https、http、ftp、file 協議讀取網絡數據,以及從本地磁盤上讀取數據。註意。file 協議實際上還是從本地磁盤讀取數據。
在 Linux 操作系統中編譯和執行:
[email protected]:~/work> dmcs CopyTester.cs StringExtensions.cs [email protected]:~/work> mono CopyTester.exe http://mysql.ntu.edu.tw/Downloads/Connector-Net/mysql-connector-net-6.5.4-noinstall.zip mysql-connector.zip [email protected]:~/work> mono CopyTester.exe ftp://ftp.ntu.edu.tw/pub/MySQL/Downloads/Connector-Net/mysql-connector-net-6.5.4-noinstall.zip mysql-connector.2.zip [email protected]:~/work> mono CopyTester.exe file:///home/ben/work/mysql-connector.zip mysql-connector.3.zip [email protected]:~/work> mono CopyTester.exe mysql-connector.zip mysql-connector.4.zip [email protected]:~/work> ls -l *.zip -rw-r--r-- 1 ben users 4176361 Mar 11 09:54 mysql-connector.2.zip -rw-r--r-- 1 ben users 4176361 Mar 11 10:01 mysql-connector.3.zip -rw-r--r-- 1 ben users 4176361 Mar 11 10:01 mysql-connector.4.zip -rw-r--r-- 1 ben users 4176361 Mar 11 09:53 mysql-connector.zip
在 Windows 操作系統能夠正常讀取網絡上的 https 數據流,在 Linux 操作系統中會失敗:
[email protected]:~/work> mono CopyTester.exe https://github.com/mono/xsp/zipball/master mono-xsp.zip Unhandled Exception: System.Net.WebException: Error getting response stream (Write: The authentication or decryption has failed.): SendFailure ---> System.IO.IOException: The authentication or decryption has failed. ---> Mono.Security.Protocol.Tls.TlsException: Invalid certificate received from server. Error code: 0xffffffff800b010a at Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.validateCertificates (Mono.Security.X509.X509CertificateCollection certificates) [0x00000] in :0 at Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.ProcessAsTls1 () [0x00000] in :0 at Mono.Security.Protocol.Tls.Handshake.HandshakeMessage.Process () [0x00000] in :0 at (wrapper remoting-invoke-with-check) Mono.Security.Protocol.Tls.Handshake.HandshakeMessage:Process () at Mono.Security.Protocol.Tls.ClientRecordProtocol.ProcessHandshakeMessage (Mono.Security.Protocol.Tls.TlsStream handMsg) [0x00000] in :0 at Mono.Security.Protocol.Tls.RecordProtocol.InternalReceiveRecordCallback (IAsyncResult asyncResult) [0x00000] in :0 --- End of inner exception stack trace --- at Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult) [0x00000] in :0 --- End of inner exception stack trace --- at System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult) [0x00000] in :0 at System.Net.HttpWebRequest.GetResponse () [0x00000] in :0 at Skyiv.StringExtensions.GetHttpStream (System.Uri uri) [0x00000] in :0 at Skyiv.StringExtensions.GetInputStream (System.String fileNameOrUri, System.String user, System.String password) [0x00000] in :0 at Skyiv.Test.CopyTester.Main (System.String[] args) [0x00000] in :0 [ERROR] FATAL UNHANDLED EXCEPTION: System.Net.WebException: Error getting response stream (Write: The authentication or decryption has failed.): SendFailure ---> System.IO.IOException: The authentication or decryption has failed. ---> Mono.Security.Protocol.Tls.TlsException: Invalid certificate received from server. Error code: 0xffffffff800b010a at Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.validateCertificates (Mono.Security.X509.X509CertificateCollection certificates) [0x00000] in :0 at Mono.Security.Protocol.Tls.Handshake.Client.TlsServerCertificate.ProcessAsTls1 () [0x00000] in :0 at Mono.Security.Protocol.Tls.Handshake.HandshakeMessage.Process () [0x00000] in :0 at (wrapper remoting-invoke-with-check) Mono.Security.Protocol.Tls.Handshake.HandshakeMessage:Process () at Mono.Security.Protocol.Tls.ClientRecordProtocol.ProcessHandshakeMessage (Mono.Security.Protocol.Tls.TlsStream handMsg) [0x00000] in :0 at Mono.Security.Protocol.Tls.RecordProtocol.InternalReceiveRecordCallback (IAsyncResult asyncResult) [0x00000] in :0 --- End of inner exception stack trace --- at Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (IAsyncResult asyncResult) [0x00000] in :0 --- End of inner exception stack trace --- at System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult) [0x00000] in :0 at System.Net.HttpWebRequest.GetResponse () [0x00000] in :0 at Skyiv.StringExtensions.GetHttpStream (System.Uri uri) [0x00000] in :0 at Skyiv.StringExtensions.GetInputStream (System.String fileNameOrUri, System.String user, System.String password) [0x00000] in :0 at Skyiv.Test.CopyTester.Main (System.String[] args) [0x00000] in :0
不知道是不是我的 openSUSE 12.1 操作系統或者是 Mono 2.10.6 執行環境還須要進行一些配置,以便滿足 https 的安全驗證要求。可是我在 Windows 操作系統中也沒有進行特別的配置。並且在 Linux 操作系統中使用 wget 命令也可下面載 https 協議的數據:
[email protected]:~/work> wget https://github.com/mono/xsp/zipball/master asking libproxy about url ‘https://github.com/mono/xsp/zipball/master‘ libproxy suggest to use ‘direct://‘ --2012-03-11 13:48:32-- https://github.com/mono/xsp/zipball/master Resolving github.com (github.com)... 207.97.227.239 Connecting to github.com (github.com)|207.97.227.239|:443... connected. HTTP request sent, awaiting response... 302 Found Location: https://nodeload.github.com/mono/xsp/zipball/master [following] asking libproxy about url ‘https://nodeload.github.com/mono/xsp/zipball/master‘ libproxy suggest to use ‘direct://‘ --2012-03-11 13:48:34-- https://nodeload.github.com/mono/xsp/zipball/master Resolving nodeload.github.com (nodeload.github.com)... 207.97.227.252 Connecting to nodeload.github.com (nodeload.github.com)|207.97.227.252|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 468024 (457K) [application/octet-stream] Saving to: `master‘ 100%[======================================>] 468,024 46.5K/s in 17s 2012-03-11 13:48:54 (27.0 KB/s) - `master‘ saved [468024/468024] [email protected]:~/work> mv master mono-xsp.zip
這樣看來。Mono 環境的 HttpWebRequest 類可能須要進行一些設置才幹讀取 https 協議的數據。
假設有哪位園友知道的話,請在本文的評論裏告訴我,謝謝。
給 string 添加一個 GetInputStream 擴展方法