用 WebClient.UploadData 方法 下载文件数据

如某网站有个表单，例如(url: http://localhost/login.aspx)：
帐号
密码

我们需要在程序中提交数据到这个表单，对于这种表单，我们可以使用 WebClient.UploadData 方法来实现，将所要上传的数据拼成字符即可，程序很简单：

string uriString = "http://localhost/login.aspx";
// 创建一个新的 WebClient 实例.
WebClient myWebClient = new WebClient();
string postData = "Username=admin&Password=admin";
// 注意这种拼字符串的ContentType
myWebClient.Headers.Add("Content-Type","application/x-www-form-urlencoded");
// 转化成二进制数组
byte[] byteArray = Encoding.ASCII.GetBytes(postData);
// 上传数据，并获取返回的二进制数据.
byte[] responseArray = myWebClient.UploadData(uriString,"POST",byteArray);


对于文件上传类的表单，例如(url: http://localhost/uploadFile.aspx)：
文件

对于这种表单，我们可以使用
String uriString = "http://localhost/uploadFile.aspx";

// 创建一个新的 WebClient 实例.
WebClient myWebClient = new WebClient();

string fileName = @"C:/upload.txt";

// 直接上传，并获取返回的二进制数据.
byte[] responseArray = myWebClient.UploadFile(uriString,"POST",fileName);


还有一种表单，不仅有文字，还有文件，例如(url: http://localhost/uploadData.aspx)：
文件名
文件

对于这种表单，似乎前面的两种方法都不能适用，对于第一种方法，不能直接拼字符串，对于第二种，我们只能传文件，重新回到第一个方法，注意参数：
public byte[] UploadData(
string address,
string method,
byte[] data
);
在第一个例子中，是通过拼字符串来得到byte[] data参数值的，对于这种表单显然不行，反过来想想，对于uploadData.aspx这样的程序来说，直接通过网页提交数据，后台所获取到的流是什么样的呢？（在我以前的一篇blog中，曾分析过这个问题：asp无组件上传进度条解决方案），最终的数据如下：

-----------------------------7d429871607fe
Content-Disposition: form-data; name="file1"; filename="G:/homepage.txt"
Content-Type: text/plain
宝玉：http://www.webuc.net
-----------------------------7d429871607fe
Content-Disposition: form-data; name="filename"
default filename
-----------------------------7d429871607fe--


所以只要拼一个这样的byte[] data数据Post过去，就可以达到同样的效果了。但是一定要注意，对于这种带有文件上传的，其ContentType是不一样的，例如上面的这种，其ContentType为"multipart/form-data; boundary=---------------------------7d429871607fe"。有了ContentType，我们就可以知道boundary(就是上面的"---------------------------7d429871607fe")，知道boundary了我们就可以构造出我们所需要的byte[] data了，最后，不要忘记，把我们构造的ContentType传到WebClient中（例如:webClient.Headers.Add("Content-Type", ContentType);）这样，就可以通过WebClient.UploadData 方法上载文件数据了。

具体代码如下：
生成二进制数据类的封装

using System;
using System.Web;
using System.IO;
using System.Net;
using System.Text;
using System.Collections;

namespace UploadData.Common
...{
/**//// <summary>
/// 创建WebClient.UploadData方法所需二进制数组
/// </summary>
public class CreateBytes
...{
Encoding encoding = Encoding.UTF8;

/**//// <summary>
/// 拼接所有的二进制数组为一个数组
/// </summary>
/// <param name="byteArrays">数组</param>
/// <returns></returns>
/// <remarks>加上结束边界</remarks>
public byte[] JoinBytes(ArrayList byteArrays)
...{
int length = 0;
int readLength = 0;

// 加上结束边界
string endBoundary = Boundary + "--/r/n"; //结束边界
byte[] endBoundaryBytes = encoding.GetBytes(endBoundary);
byteArrays.Add(endBoundaryBytes);

foreach(byte[] b in byteArrays)
...{
length += b.Length;
}
byte[] bytes = new byte[length];

// 遍历复制
//
foreach(byte[] b in byteArrays)
...{
b.CopyTo(bytes, readLength);
readLength += b.Length;
}

return bytes;
}

public bool UploadData(string uploadUrl, byte[] bytes, out byte[] responseBytes)
...{
WebClient webClient = new WebClient();
webClient.Headers.Add("Content-Type", ContentType);

try
...{
responseBytes = webClient.UploadData(uploadUrl, bytes);
return true;
}
catch (WebException ex)
...{
Stream resp = ex.Response.GetResponseStream();
responseBytes = new byte[ex.Response.ContentLength];
resp.Read(responseBytes, 0, responseBytes.Length);
}
return false;
}



/**//// <summary>
/// 获取普通表单区域二进制数组
/// </summary>
/// <param name="fieldName">表单名</param>
/// <param name="fieldValue">表单值</param>
/// <returns></returns>
/// <remarks>
/// -----------------------------7d52ee27210a3c/r/nContent-Disposition: form-data; name=/"表单名/"/r/n/r/n表单值/r/n
/// </remarks>
public byte[] CreateFieldData(string fieldName, string fieldValue)
...{
string textTemplate = Boundary + "/r/nContent-Disposition: form-data; name=/"{0}/"/r/n/r/n{1}/r/n";
string text = String.Format(textTemplate, fieldName, fieldValue);
byte[] bytes = encoding.GetBytes(text);
return bytes;
}


/**//// <summary>
/// 获取文件上传表单区域二进制数组
/// </summary>
/// <param name="fieldName">表单名</param>
/// <param name="filename">文件名</param>
/// <param name="contentType">文件类型</param>
/// <param name="contentLength">文件长度</param>
/// <param name="stream">文件流</param>
/// <returns>二进制数组</returns>
public byte[] CreateFieldData(string fieldName, string filename,string contentType, byte[] fileBytes)
...{
string end = "/r/n";
string textTemplate = Boundary + "/r/nContent-Disposition: form-data; name=/"{0}/"; filename=/"{1}/"/r/nContent-Type: {2}/r/n/r/n";

// 头数据
string data = String.Format(textTemplate, fieldName, filename, contentType);
byte[] bytes = encoding.GetBytes(data);



// 尾数据
byte[] endBytes = encoding.GetBytes(end);

// 合成后的数组
byte[] fieldData = new byte[bytes.Length + fileBytes.Length + endBytes.Length];

bytes.CopyTo(fieldData, 0); // 头数据
fileBytes.CopyTo(fieldData, bytes.Length); // 文件的二进制数据
endBytes.CopyTo(fieldData, bytes.Length + fileBytes.Length); // /r/n

return fieldData;
}


属性#region 属性
public string Boundary
...{
get
...{
string[] bArray, ctArray;
string contentType = ContentType;
ctArray = contentType.Split(';');
if (ctArray[0].Trim().ToLower() == "multipart/form-data")
...{
bArray = ctArray[1].Split('=');
return "--" + bArray[1];
}
return null;
}
}

public string ContentType
...{
get ...{
if (HttpContext.Current == null)
...{
return "multipart/form-data; boundary=---------------------------7d5b915500cee";
}
return HttpContext.Current.Request.ContentType;
}
}
#endregion
}
}


在Winform中调用


using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;

using UploadData.Common;
using System.IO;

namespace UploadDataWin
...{
/**//// <summary>
/// frmUpload 的摘要说明。
/// </summary>
public class frmUpload : System.Windows.Forms.Form
...{
private System.Windows.Forms.Label lblAmigoToken;
private System.Windows.Forms.TextBox txtAmigoToken;
private System.Windows.Forms.Label lblFilename;
private System.Windows.Forms.TextBox txtFilename;
private System.Windows.Forms.Button btnBrowse;
private System.Windows.Forms.TextBox txtFileData;
private System.Windows.Forms.Label lblFileData;
private System.Windows.Forms.Button btnUpload;
private System.Windows.Forms.OpenFileDialog openFileDialog1;
private System.Windows.Forms.TextBox txtResponse;
/**//// <summary>
/// 必需的设计器变量。
/// </summary>
private System.ComponentModel.Container components = null;

public frmUpload()
...{
//
// Windows 窗体设计器支持所必需的
//
InitializeComponent();

//
// TODO: 在 InitializeComponent 调用后添加任何构造函数代码
//
}

/**//// <summary>
/// 清理所有正在使用的资源。
/// </summary>
protected override void Dispose( bool disposing )
...{
if( disposing )
...{
if (components != null)
...{
components.Dispose();
}
}
base.Dispose( disposing );
}

Windows 窗体设计器生成的代码#region Windows 窗体设计器生成的代码
/**//// <summary>
/// 设计器支持所需的方法 - 不要使用代码编辑器修改
/// 此方法的内容。
/// </summary>
private void InitializeComponent()
...{
this.lblAmigoToken = new System.Windows.Forms.Label();
this.txtAmigoToken = new System.Windows.Forms.TextBox();
this.lblFilename = new System.Windows.Forms.Label();
this.txtFilename = new System.Windows.Forms.TextBox();
this.btnBrowse = new System.Windows.Forms.Button();
this.txtFileData = new System.Windows.Forms.TextBox();
this.lblFileData = new System.Windows.Forms.Label();
this.btnUpload = new System.Windows.Forms.Button();
this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog();
this.txtResponse = new System.Windows.Forms.TextBox();
this.SuspendLayout();
//
// lblAmigoToken
//
this.lblAmigoToken.Location = new System.Drawing.Point(40, 48);
this.lblAmigoToken.Name = "lblAmigoToken";
this.lblAmigoToken.Size = new System.Drawing.Size(72, 23);
this.lblAmigoToken.TabIndex = 0;
this.lblAmigoToken.Text = "AmigoToken";
//
// txtAmigoToken
//
this.txtAmigoToken.Location = new System.Drawing.Point(120, 48);
this.txtAmigoToken.Name = "txtAmigoToken";
this.txtAmigoToken.Size = new System.Drawing.Size(248, 21);
this.txtAmigoToken.TabIndex = 1;
this.txtAmigoToken.Text = "";
//
// lblFilename
//
this.lblFilename.Location = new System.Drawing.Point(40, 96);
this.lblFilename.Name = "lblFilename";
this.lblFilename.Size = new System.Drawing.Size(80, 23);
this.lblFilename.TabIndex = 2;
this.lblFilename.Text = "Filename";
//
// txtFilename
//
this.txtFilename.Location = new System.Drawing.Point(120, 96);
this.txtFilename.Name = "txtFilename";
this.txtFilename.Size = new System.Drawing.Size(248, 21);
this.txtFilename.TabIndex = 3;
this.txtFilename.Text = "";
//
// btnBrowse
//
this.btnBrowse.Location = new System.Drawing.Point(296, 144);
this.btnBrowse.Name = "btnBrowse";
this.btnBrowse.TabIndex = 4;
this.btnBrowse.Text = "浏览...";
this.btnBrowse.Click += new System.EventHandler(this.btnBrowse_Click);
//
// txtFileData
//
this.txtFileData.Location = new System.Drawing.Point(120, 144);
this.txtFileData.Name = "txtFileData";
this.txtFileData.Size = new System.Drawing.Size(168, 21);
this.txtFileData.TabIndex = 5;
this.txtFileData.Text = "";
//
// lblFileData
//
this.lblFileData.Location = new System.Drawing.Point(40, 144);
this.lblFileData.Name = "lblFileData";
this.lblFileData.Size = new System.Drawing.Size(72, 23);
this.lblFileData.TabIndex = 6;
this.lblFileData.Text = "FileData";
//
// btnUpload
//
this.btnUpload.Location = new System.Drawing.Point(48, 184);
this.btnUpload.Name = "btnUpload";
this.btnUpload.TabIndex = 7;
this.btnUpload.Text = "Upload";
this.btnUpload.Click += new System.EventHandler(this.btnUpload_Click);
//
// txtResponse
//
this.txtResponse.Location = new System.Drawing.Point(136, 184);
this.txtResponse.Multiline = true;
this.txtResponse.Name = "txtResponse";
this.txtResponse.Size = new System.Drawing.Size(248, 72);
this.txtResponse.TabIndex = 8;
this.txtResponse.Text = "";
//
// frmUpload
//
this.AutoScaleBaseSize = new System.Drawing.Size(6, 14);
this.ClientSize = new System.Drawing.Size(400, 269);
this.Controls.Add(this.txtResponse);
this.Controls.Add(this.btnUpload);
this.Controls.Add(this.lblFileData);
this.Controls.Add(this.txtFileData);
this.Controls.Add(this.btnBrowse);
this.Controls.Add(this.txtFilename);
this.Controls.Add(this.lblFilename);
this.Controls.Add(this.txtAmigoToken);
this.Controls.Add(this.lblAmigoToken);
this.Name = "frmUpload";
this.Text = "frmUpload";
this.ResumeLayout(false);

}
#endregion

/**//// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
...{
Application.Run(new frmUpload());
}

private void btnUpload_Click(object sender, System.EventArgs e)
...{
// 非空检验
if (txtAmigoToken.Text.Trim() == "" || txtFilename.Text == "" || txtFileData.Text.Trim() == "")
...{
MessageBox.Show("Please fill data");
return;
}

// 所要上传的文件路径
string path = txtFileData.Text.Trim();

// 检查文件是否存在
if (!File.Exists(path))
...{
MessageBox.Show("{0} does not exist!", path);
return;
}

// 读文件流
FileStream fs = new FileStream(path, FileMode.Open,
FileAccess.Read, FileShare.Read);

// 这部分需要完善
string ContentType = "application/octet-stream";
byte[] fileBytes = new byte[fs.Length];
fs.Read(fileBytes, 0, Convert.ToInt32(fs.Length));


// 生成需要上传的二进制数组
CreateBytes cb = new CreateBytes();
// 所有表单数据
ArrayList bytesArray = new ArrayList();
// 普通表单
bytesArray.Add(cb.CreateFieldData("FileName", txtFilename.Text));
bytesArray.Add(cb.CreateFieldData("AmigoToken", txtAmigoToken.Text));
// 文件表单
bytesArray.Add(cb.CreateFieldData("FileData", path
, ContentType, fileBytes));

// 合成所有表单并生成二进制数组
byte[] bytes = cb.JoinBytes(bytesArray);

// 返回的内容
byte[] responseBytes;

// 上传到指定Url
bool uploaded = cb.UploadData("http://localhost/UploadData/UploadAvatar.aspx", bytes, out responseBytes);

// 将返回的内容输出到文件
using (FileStream file = new FileStream(@"c:/response.text", FileMode.Create, FileAccess.Write, FileShare.Read))
...{
file.Write(responseBytes, 0, responseBytes.Length);
}

txtResponse.Text = System.Text.Encoding.UTF8.GetString(responseBytes);

}

private void btnBrowse_Click(object sender, System.EventArgs e)
...{
if(openFileDialog1.ShowDialog() == DialogResult.OK)
...{
txtFileData.Text = openFileDialog1.FileName;
}

}
}
}


完整的代码见附件: UploadData.rar(38K)(http://bbs.openlab.net.cn/PostAttachment.aspx?PostID=400927)，解压后给web目录建个虚拟目录"UploadData"，其中UploadAvatar.aspx是实际的上传处理页，如果上传成功，则返回文件名和文件类型等信息。default.aspx是asp.net页面来调用 WebClient.UploadData方法提交数据，UploadDataWin项目则是winform程序调用。 <!--内容正文-->