JAVA高级面试进阶训练营视频教程

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1) 方案一,  使用Web Service  基础功能没问题, 只是在连接https (ssh) 网站时, 需要针对https进行开发 (即http 和https 生成两套接口, 不太容易统一 ).   后来改为使用web页面交互(实质是.ashx) 结果也遇到了不少问题.

 

2) 方案二, 使用  HttpWebRequest .      HttpWebRequest  这东西get数据很容易, POST却很麻烦, 最终代码如下:

 

 1 public class WebApiClient
 2     {
 3         public string Url { get; set; }
 4         private CookieContainer Cookies = new CookieContainer();
 5          
 6           
 7         public static string Get( string url )
 8         {
 9             //this code can fix https after .net 4.6
10             if (url.StartsWith("https", StringComparison.CurrentCultureIgnoreCase))
11             {
12                 System.Net.ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
13             }
14             System.Net.HttpWebRequest request = (System.Net.HttpWebRequest)WebRequest.Create(url);
15             request.Method = "GET";
16             request.ContentType = "application/x-www-form-urlencoded";
17              
18             System.Net.HttpWebResponse response = (System.Net.HttpWebResponse)request.GetResponse();
19             System.IO.Stream s = response.GetResponseStream();
20             using (StreamReader reader = new StreamReader(s))
21             { 
22                 string strValue = reader.ReadToEnd();
23                 return strValue;
24             }
25         }
26         private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
27         {
28             return true;  
29         }
30         public Result<DataTable> CallWebApi(string action, string json )
31         {
32             return CallWebApi(action, json, null, null);
33         }
34         public Result<DataTable> CallWebApi(string action, string json, string fileName, byte[] fileData)
35         {
36             string responseContent;
37             var memStream = new MemoryStream();
38             var webRequest = (HttpWebRequest)WebRequest.Create(Url); 
39             var boundary = "---------------" + DateTime.Now.Ticks.ToString("x"); 
40             var beginBoundary = Encoding.ASCII.GetBytes("--" + boundary + "\r\n");
41             //var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read); 
42             var endBoundary = Encoding.ASCII.GetBytes("--" + boundary + "--\r\n"); 
43             webRequest.Method = "POST"; 
44             //webRequest.Timeout = timeOut;
45             webRequest.ContentType = "multipart/form-data; boundary=" + boundary;
46             if (!string.IsNullOrEmpty(fileName))
47             {
48                 const string filePartHeader =
49                "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\n" +
50                 "Content-Type: application/octet-stream\r\n\r\n";
51                 var header = string.Format(filePartHeader, "file1", fileName);
52                 var headerbytes = Encoding.UTF8.GetBytes(header);
53                 memStream.Write(beginBoundary, 0, beginBoundary.Length);
54                 memStream.Write(headerbytes, 0, headerbytes.Length);
55                 memStream.Write(fileData, 0, fileData.Length);
56             }
57             
58             
59             var stringKeyHeader = "\r\n--" + boundary +
60                                    "\r\nContent-Disposition: form-data; name=\"{0}\"" +
61                                    "\r\n\r\n{1}\r\n";
62             var bytes = Encoding.UTF8.GetBytes(string.Format(stringKeyHeader, "action", action));
63             memStream.Write(bytes, 0, bytes.Length);
64             bytes = Encoding.UTF8.GetBytes(string.Format(stringKeyHeader, "json", json));
65             memStream.Write(bytes, 0, bytes.Length);
66              
67             memStream.Write(endBoundary, 0, endBoundary.Length);
68             webRequest.ContentLength = memStream.Length;
69             var requestStream = webRequest.GetRequestStream();
70             memStream.Position = 0;
71             var tempBuffer = new byte[memStream.Length];
72             memStream.Read(tempBuffer, 0, tempBuffer.Length);
73             memStream.Close();
74             requestStream.Write(tempBuffer, 0, tempBuffer.Length);
75             requestStream.Close();
76             var httpWebResponse = (HttpWebResponse)webRequest.GetResponse();
77             using (var httpStreamReader = new StreamReader(httpWebResponse.GetResponseStream(),
78                                                             Encoding.GetEncoding("utf-8")))
79             {
80                 responseContent = httpStreamReader.ReadToEnd();
81             } 
82             httpWebResponse.Close();
83             webRequest.Abort();
84             try
85             {
86                 return JsonConvert.DeserializeObject<Result<DataTable>>(responseContent);
87             }
88             catch (Exception ex)
89             {
90                 throw new ApplicationException("Parse server result error: " + responseContent, ex);
91             } 
92         }
93          
94     }

View Code

 

POST数据的麻烦, 封装一下可以忍了, 但是连接HTTPS的网站时, 有的网站可以, 有的网站会出错: System.Net.WebException: The underlying connection was closed: An unexpected error occurred on a send. ---> System.IO.IOException: Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. ---> System.Net.Sockets.SocketException: An existing connection was forcibly closed by the remote host

   at System.Net.Sockets.Socket.Receive(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)

   at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)

   --- End of inner exception stack trace ---

   at System.Net.Sockets.NetworkStream.Read(Byte[] buffer, Int32 offset, Int32 size)

   at System.Net.FixedSizeReader.ReadPacket(Byte[] buffer, Int32 offset, Int32 count)

   at System.Net.Security.SslState.StartReceiveBlob(Byte[] buffer, AsyncProtocolRequest asyncRequest)

   at System.Net.Security.SslState.ForceAuthentication(Boolean receiveFirst, Byte[] buffer, AsyncProtocolRequest asyncRequest)

   at System.Net.Security.SslState.ProcessAuthentication(LazyAsyncResult lazyResult)

   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)

   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)

   at System.Net.TlsStream.ProcessAuthentication(LazyAsyncResult result)

   at System.Net.TlsStream.Write(Byte[] buffer, Int32 offset, Int32 size)

   at System.Net.ConnectStream.WriteHeaders(Boolean async)

   --- End of inner exception stack trace ---

   at System.Net.HttpWebRequest.GetResponse()

 

如果是普通的桌面程序 , 在.net 4.6以上版本时, Create  HttpWebRequest 对象前添加

1. if(url.StartsWith("https",StringComparison.CurrentCultureIgnoreCase))
2. {
3. System.Net.ServicePointManager.ServerCertificateValidationCallback=newRemoteCertificateValidationCallback(CheckValidationResult);
4. }

1. privatestatic bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain,SslPolicyErrors errors)
2. {
3. returntrue;
4. }

 

有的web服务器要求较新的HTTPS的安装协议, 这种情况下.net4.0以下的版本不支持, 因此要升级到.net4.6以上, 并且在创建HttpWebRequest对象前加入如下设置代码:

1. ServicePointManager.SecurityProtocol=SecurityProtocolType.Tls|SecurityProtocolType.Tls11|SecurityProtocolType.Tls12|SecurityProtocolType.Ssl3;

这样就可以最大程度的兼容各种安全协议了. 有的时候发现我们的程序挑.net framework的版本, 大都是由这个原因引起的.

解决了HttpWebRequest连接HTTPS的问题之后, 该方案成为了功能最强的方案(重要是能较好的支持文件的上传)

 

方案三 使用WebBrowser控件 .

 

初步试了一下, get https的页面没有问题, post 的略有麻烦, 网上查到的方法是截获post事件进行处理:

WebBrowser 其实是对 ActiveX 控件 SHDocVw 的封装，而这个SHDocVw的很多底层调用WebBrowser控件并没有提供实现，我们需要直接操作 SHDoceVw 控件来实现这些高级调用。操作方法如下： 1、在 windows/system32 目录下找到 shdocvw.dll 这个动态库，将其添加到引用中 2、在 Form1_Load 中添加如下语句 SHDocVw.WebBrowser wb = (SHDocVw.WebBrowser)webBrowser1.ActiveXInstance; wb.BeforeNavigate2 += new DWebBrowserEvents2_BeforeNavigate2EventHandler(WebBrowser_BeforeNavigate2); 3、添加如下成员函数 private void WebBrowser_BeforeNavigate2(object pDisp, ref object URL, ref object Flags, ref object TargetFrameName, ref object PostData, ref object Headers, ref bool Cancel) { string postDataText = System.Text.Encoding.ASCII.GetString(PostData as byte[]); } 完成上述3步后，你post 数据时， 就会响应 BeforeNavigate2 事件，postDataText 中就是你post的数据。你也可以修改PostData，对这些数据进行转换或加密。 来源： http://www.cnblogs.com/swtseaman/archive/2011/10/17/2215717.html

感觉会比较麻烦, 其实还有一种方法,就是利用WebBrowser的DocumentText属性注入脚本(执行脚本), 然后利用Ajax的方式和web服务器进行交互. 之后利用JS和C#互操作来完成相应的功能.

互操作的C#类上需要加上这个设置:

1. [System.Runtime.InteropServices.ComVisibleAttribute(true)]

并且运行此代码:

1. webBrowser1.ObjectForScripting=this;

C#里调用JS方法:

1. webBrowser1.Document.InvokeScript("jsFunction",newstring[]{‘ssss’});

 

JS里调用C#方法:

1. window.external.CSharpFunction(‘呵呵’);

这个方法也有些麻烦的地方, 而且不支持文件的上传.

 

来自为知笔记(Wiz)