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：

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：

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

-----------------------------7d429871607fe
content-disposition: form-data; name="file1"; filename="g:/homepage.txt"
content-type: text/plain
：//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;
      }
    }
  }
}