Asp.Net模拟表单提交数据和上传文件的实现代码

如果你需要跨域上传内容到另外一个域名并且需要获取返回值，使用Asp.Net的作为代理是最好的办法，要是客户端直接提交到iframe中，由于跨域是无法用javascript获取到iframe中返回的内容的。此时需要在自己的网站做一个动态页作为代理，将表单提交到动态页，动态页负责将表单的内容使用WebClient或HttpWebRequest将表单数据再上传到远程服务器，由于在服务器端进行操作，就不存在跨域问题了。

WebClient上传只包含键值对的文本信息示例代码：

代码如下:

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);

WebClient上传只包含文件的示例代码：

代码如下:

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);

　对于既包含文件又包含文本键值对信息的示例代码，需要构造表单提交的内容，对于学asp的同学来说，下面的表单提交内容一定不会陌生

代码如下:

-----------------------------7d429871607fe
Content-Disposition: form-data; name="file1"; filename="G:/homepage.txt"
Content-Type: text/plain
我们：http://www.jb51.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。

using System;
using System.Web;
using System.IO;
using System.Net;
using System.Text;
using System.Collections;
namespace UploadData.Common
{
  public class CreateBytes
  {
    Encoding encoding = Encoding.UTF8;
    public byte[] JoinBytes(ArrayList byteArrays)
    {
      int length = 0;
      int readLength = 0;
      // 加上结束边界
      string endBoundary = Boundary + "-- ";
      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;
    }
    /// 获取普通表单区域二进制数组
    public byte[] CreateFieldData(string fieldName, string fieldValue)
    {
      string textTemplate = Boundary + " Content-Disposition: form-data; name="{0}" {1} ";
      string text = String.Format(textTemplate, fieldName, fieldValue);
      byte[] bytes = encoding.GetBytes(text);
      return bytes;
    }
    public byte[] CreateFieldData(string fieldName, string filename, string contentType, byte[] fileBytes)
    {
      string end = " ";
      string textTemplate = Boundary + " Content-Disposition: form-data; name="{0}"; filename="{1}" Content-Type: {2} ";
      // 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); //
      return fieldData;
    }
    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;
      }
    }
  }
}
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
{
  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;
    private System.ComponentModel.Container components = null;
    public frmUpload()
    {
      InitializeComponent();
    }
    protected override void Dispose(bool disposing)
    {
      if (disposing)
      {
        if (components != null)
        {
          components.Dispose();
        }
      }
      base.Dispose(disposing);
    }
    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);
    }
    [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: esponse.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;
      }
    }
  }
}