WCF系列_WCF影响客户端导出Excel文件的实现

需求：WCF搭建服务端提供导出并下载Excel文件接口，客户端使用ajax发起请求，浏览器直接下载Excel文件。

难点：WCF中并没有HttpContext对象，因此，服务端总是获取不到HttpContext.Current值。即HttpContext.Current=null。

使用WebFrom的方法已经不能实现需求了。

HttpContext.Current.Response.ContentType = "application/ms-excel";
HttpContext.Current.Response.ContentEncoding = Encoding.UTF8;
HttpContext.Current.Response.Charset = "";
HttpContext.Current.Response.AppendHeader("Content-Disposition","attachment;filename=" + HttpUtility.UrlEncode(excelConfig.FileName, Encoding.UTF8));
HttpContext.Current..Response.BinaryWrite(...);
HttpContext.Current..Response.End();

方案：兼容模式下，使用WebOperationContext.Current.OutgoingResponse

public Stream DownloadFileFromWCF()
{
Stream fileStream = null;
try
{
DataTable dtExport = null; //要导出的数据源
#region 转换为流
string fileString = ToStringCSV(dtExport, ",", true);
fileString = ToStringXLS(dtExport, false);
// byte[] array = Encoding.ASCII.GetBytes(fileString);//中文乱码
byte[] array = System.Text.Encoding.UTF8.GetBytes(fileString);//中文乱码
array = System.Text.Encoding.Default.GetBytes(fileString);
MemoryStream stream = new MemoryStream(array);
fileStream = stream;
#endregion

//从硬盘文件读取数据源
//string fileFullPath = @"C:\Users\dell\Desktop\投注页相关接口.txt";
//fileStream = File.OpenRead(fileFullPath);

string saveFileName = "Test.xls";

//WebOperationContext.Current.OutgoingResponse.ContentType = "application/json; charset=utf-8";
//WebOperationContext.Current.OutgoingResponse.Headers.Add("Content-Encoding", "gzip");

//WebOperationContext.Current.OutgoingResponse.ContentType = "text/html; charset=utf-8";
WebOperationContext.Current.OutgoingResponse.ContentType = "application/json; charset=utf-8";
WebOperationContext.Current.OutgoingResponse.Headers.Add("Content-Disposition", "attachment;filename=" + HttpUtility.UrlPathEncode(saveFileName));
}
catch (Exception ex)
{
}

return fileStream;
}
/// <summary>
/// dt转CSV格式文件字符串
/// </summary>
/// <param name="table"></param>
/// <param name="delimiter">分隔符=","</param>
/// <param name="includeHeader">是否包括数据表头</param>
/// <returns></returns>
private string ToStringCSV(DataTable dt, string delimiter, bool includeHeader)
{
var result = new StringBuilder();

if (includeHeader)
{
foreach (DataColumn column in dt.Columns)
{
result.Append(column.ColumnName);
result.Append(delimiter);
}

result.Remove(--result.Length, 0);
result.Append(Environment.NewLine);
}

string itemAsString = string.Empty;
foreach (DataRow row in dt.Rows)
{
foreach (object item in row.ItemArray)
{
itemAsString = string.Empty;

if (item is DBNull)
result.Append(delimiter);
else
{
itemAsString = item.ToString();
// Double up all embedded double quotes
itemAsString = itemAsString.Replace("\"", "\"\"");

// To keep things simple, always delimit with double-quotes
// so we don't have to determine in which cases they're necessary
// and which cases they're not.
itemAsString = "\"" + itemAsString + "\"";

result.Append(itemAsString + delimiter);
}
}

result.Remove(--result.Length, 0);
result.Append(Environment.NewLine);
}

return result.ToString();
}

/// <summary>
/// dt转XLS格式文件字符串
/// </summary>
/// <param name="dt"></param>
/// <param name="includeHeader"></param>
/// <returns></returns>
private string ToStringXLS(DataTable dt, bool includeHeader)
{
var result = new StringBuilder();

string delimiter = "";
if (includeHeader)
{
foreach (DataColumn dc in dt.Columns)
{
result.Append(delimiter + dc.ColumnName);
delimiter = "\t";

}
//result.Append("\n");
result.Append(Environment.NewLine);
}

foreach (DataRow dr in dt.Rows)
{
delimiter = "";
for (int i = 0; i < dt.Columns.Count; i++)
{
result.Append(delimiter + dr[i].ToString());
delimiter = "\t";
}
//result.Append("\n");
result.Append(Environment.NewLine);
}

return result.ToString();
}