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无刷新上传解析csv文件

　　前阵子工作中用到，贴上代码，仅保留上传有关的代码，发现code其实很少。

上传页面html/js

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title></title>
    <script type="text/javascript">
        function FinishUpload(filePath) {                   
            document.getElementById("uploadForm").reset();
            if (!filePath) {
                alert("Import Failed!");
            }
            else {
                alert("Imported Successfully to " + decodeURIComponent(filePath) + "!");
                
            }
        }

        function UploadFile() {
            var arr = document.getElementById("txtFile").value.split('.');
            var fileType = arr[arr.length - 1];
            if (fileType.toLowerCase().indexOf("csv") < 0) {
                document.getElementById("uploadForm").reset();
                alert("Please select a csv file.");
                return false;
            }

            document.getElementById("uploadForm").encoding = "multipart/form-data";
            document.getElementById("uploadForm").submit();
        }
        
        function ResetFile(file) {
            var tmpForm = document.createElement('form');
            file.parentNode.insertBefore(tmpForm, file);
            tmpForm.appendChild(file);
            tmpForm.reset();
            tmpForm.removeNode(false);
        }
    </script>
</head>
<body>
<form id="uploadForm" name="uploadForm" action="Upload.ashx" method="post" target="hidIframe" enctype="multipart/form-data">
  <table cellpadding='0' cellspacing='0' style="width:100%;height:100%;border-collapse:collapse;" border="0" >
        <tr>
            <td>
                <input id="txtFile" name="txtFile" type="file"  style="border:solid 1px Gray;" />              
                <iframe name="hidIframe" id="hidIframe" style="display:none;" ></iframe>
            </td>
         </tr>
       
        <tr>
            <td>
                <input type="button"  id="btnImportOK" value="Upload" onclick="UploadFile();" />
                <input type="button"  id="btnImportCancel" onclick="ResetFile(document.getElementById('txtFile'))"  value="Reset"/>                
            </td>
        </tr>
    </table>   
</form>
</body>
</html>

处理文件上传的c#code

if (context.Request.Files.Count > 0)
            {
                HttpPostedFile file = context.Request.Files[0];
                if (file.ContentLength > 0)
                {
                    string title = string.Empty;
                    title = DateTime.Now.ToString("yyyyMMddHHmmss") + "_" + Path.GetFileName(file.FileName);
                    string path = "./Upload/" + title;
                    path = System.Web.HttpContext.Current.Server.MapPath(path);
                    file.SaveAs(path);
                    context.Response.Write("<script>window.parent.FinishUpload('" + HttpUtility.UrlEncode(path) + "');</script>");
                }
            }
            else
            {
                context.Response.Write("<script>window.parent.FinishUpload('');</script>");
            }

　　做到无刷新，基本原理就是：通过表单提交到iframe里，从而使刷新发生在iframe里。form设置action指向处理上传的文件，target指向iframe。上传操作的结果可以返回到iframe里，调用父对象的FinishUpload方法显示是否上传成功。所以在AJAX未流行时，常用这种方法来伪装未刷新的效果，现在仍然可以使用。

要注意的是：

enctype="multipart/form-data"不可少，enctype默认编码是“application/x-www-form-urlencoded”，设置enctype="multipart/form-data"，用于二进制方式上传文件。
为防止文件名乱码，防止乱七八糟字符URL传递中出现问题，返回文件名到前台时进行HttpUtility.UrlEncode，在前台JS中取文件名时进行decodeURIComponent。
重置文件选择框时，要把文件选择框临时插入到临时表单，通过表单的reset方法重置。

顺便贴上解析上传的csv文件的code

解析csv文件

private DataTable ImportDataTable(string filepath)
        {            
            DataTable mydt = new DataTable("myTableName");
            mydt.Columns.Add("Data ID", System.Type.GetType("System.String"));
            mydt.Columns.Add("Field Name", System.Type.GetType("System.String"));
            mydt.Columns.Add("New Value", System.Type.GetType("System.String"));
            DataRow mydr;
            using (System.IO.StreamReader mysr = new System.IO.StreamReader(filepath))
            {                
                int data;
                char current;
                StringBuilder text = new StringBuilder();

                IDictionary<int, List<string>> results = new Dictionary<int, List<string>>();
                bool isInYinHao = false; ;
                int lineId = 1;
                int index = 0;
                while (true)
                {
                    data = mysr.Read();
                    if (data != -1)
                    {
                        current = (char)data;
                        if (current == '"')
                        {
                            if (isInYinHao)
                            {
                                isInYinHao = false;
                            }
                            else
                            {
                                if (index > 0)
                                {
                                    text.Append(current);
                                }

                                isInYinHao = true;
                            }
                        }
                        else if (current == ',')
                        {
                            if (isInYinHao)
                            {
                                text.Append(current);
                            }
                            else
                            {

                                SaveResult(results, lineId, text);
                                index = 0;
                                continue;
                            }
                        }
                        else if (current == '\r')
                        {
                            if (isInYinHao)
                            {
                                text.Append(current);
                            }
                        }
                        else if (current == '\n')
                        {
                            if (isInYinHao)
                            {
                                text.Append(current);
                            }
                            else
                            {
                                SaveResult(results, lineId, text);
                                index = 0;
                                lineId++;
                                continue;
                            }
                        }
                        else if (current == '\0')
                        {
                        }
                        else
                        {
                            text.Append(current);
                        }

                        index++;
                    }
                    else
                    {
                        //Read to file end.
                        SaveResult(results, lineId, text);
                        break;
                    }
                }

                foreach (int id in results.Keys)
                {
                    mydr = mydt.NewRow();
                    for (int i = 0; i < results[id].Count; i++)
                    {
                        if (i > 2)
                        {
                            break;
                        }

                        mydr[i] = results[id][i];
                    }

                    mydt.Rows.Add(mydr);
                }

            }

            return mydt;
        }

        private void SaveResult(IDictionary<int, List<string>> results, int lineId, StringBuilder text)
        {
            if (!results.ContainsKey(lineId))
            {
                results.Add(lineId, new List<string>());
            }

            results[lineId].Add(text.ToString());
            text.Remove(0, text.Length);
        }