C# WebClient.DownloadFile下载后如何释放WebClient
先贴上完整的代码
[HttpPost]
[HandlerAjaxOnly]
public ActionResult export(string cp_fbill, string cp_sn)
{
string sql = "select * from customer_complaint_sp_file where cp_fbill='" + cp_fbill + "' and cp_sn=" + cp_sn + "";
DataTable dt0 = DbHelperSQL.Query(sql).Tables[0];
//获取客诉单单身customer_complaint_e_file的信息
sql = "select * from customer_complaint_e_file where cp_e_fbill='" + cp_fbill + "' and cp_e_sn=" + cp_sn + "";
DataTable dte = DbHelperSQL.Query(sql).Tables[0];
//获取客诉单单头customer_complaint_h_file的信息
sql = "select * from customer_complaint_h_file where cp_h_fbill='" + cp_fbill + "' ";
DataTable dth = DbHelperSQL.Query(sql).Tables[0];
sql = "select * from customer_complaint_sp_d1_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d1_sn=" + cp_sn + "";
DataTable dt1 = DbHelperSQL.Query(sql).Tables[0];
dt1.TableName = "d1";
sql = "select * from customer_complaint_sp_d2_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d2_sn=" + cp_sn + "";
DataTable dt2 = DbHelperSQL.Query(sql).Tables[0];
dt2.TableName = "d2";
sql = "select * from customer_complaint_sp_d3_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d3_sn=" + cp_sn + "";
DataTable dt3 = DbHelperSQL.Query(sql).Tables[0];
dt3.TableName = "d3";
sql = "select * from customer_complaint_sp_d4_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d4_sn=" + cp_sn + "";
DataTable dt4 = DbHelperSQL.Query(sql).Tables[0];
dt4.TableName = "d4";
sql = "select * from customer_complaint_sp_d5_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d5_sn=" + cp_sn + "";
DataTable dt5 = DbHelperSQL.Query(sql).Tables[0];
dt5.TableName = "d5";
sql = "select * from customer_complaint_sp_d6_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d6_sn=" + cp_sn + "";
DataTable dt6 = DbHelperSQL.Query(sql).Tables[0];
dt6.TableName = "d6";
sql = "select * from customer_complaint_sp_d7_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d7_sn=" + cp_sn + "";
DataTable dt7 = DbHelperSQL.Query(sql).Tables[0];
dt7.TableName = "d7";
sql = "select * from customer_complaint_sp_d8_file where cp_sr_fbill='" + cp_fbill + "' and cp_sr_d8_sn=" + cp_sn + "";
DataTable dt8 = DbHelperSQL.Query(sql).Tables[0];
dt8.TableName = "d8";
WorkbookDesigner designer = new WorkbookDesigner();
designer.Open(Server.MapPath("~/Content/template/客诉8D报告导出.xlsx"));
Dictionary<string, string> dict = new Dictionary<string, string>();
if (dt0.Rows.Count > 0)
{
designer.SetDataSource("cp_fbill", dt0.Rows[0]["cp_fbill"] == DBNull.Value ? "" : dt0.Rows[0]["cp_fbill"].ToString());
designer.SetDataSource("cp_sn", dt0.Rows[0]["cp_sn"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sn"].ToString());
designer.SetDataSource("cp_sr_status", dt0.Rows[0]["cp_sr_status"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sr_status"].ToString());
designer.SetDataSource("cp_sr_confirmer", dt0.Rows[0]["cp_sr_confirmer"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sr_confirmer"].ToString());
designer.SetDataSource("cp_sr_confirm_date", dt0.Rows[0]["cp_sr_confirm_date"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sr_confirm_date"].ToString());
designer.SetDataSource("cp_sr_item_code", dt0.Rows[0]["cp_sr_item_code"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sr_item_code"].ToString());
designer.SetDataSource("cp_sr_item_name", dt0.Rows[0]["cp_sr_item_name"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sr_item_name"].ToString());
designer.SetDataSource("cp_sr_item_type", dte.Rows[0]["cp_e_item_type"] == DBNull.Value ? "" : dte.Rows[0]["cp_e_item_type"].ToString());
designer.SetDataSource("cp_e_cu_item_code", dte.Rows[0]["cp_e_cu_item_code"] == DBNull.Value ? "" : dte.Rows[0]["cp_e_cu_item_code"].ToString());
designer.SetDataSource("cp_e_type", dte.Rows[0]["cp_e_type"] == DBNull.Value ? "" : dte.Rows[0]["cp_e_type"].ToString());
designer.SetDataSource("cp_e_problem_desc", dte.Rows[0]["cp_e_problem_desc"] == DBNull.Value ? "" : dte.Rows[0]["cp_e_problem_desc"].ToString());
designer.SetDataSource("cp_e_qty", dte.Rows[0]["cp_e_qty"] == DBNull.Value ? "" : dte.Rows[0]["cp_e_qty"].ToString());
designer.SetDataSource("cp_e_refer_qty", dte.Rows[0]["cp_e_refer_qty"] == DBNull.Value ? "" : dte.Rows[0]["cp_e_refer_qty"].ToString());
designer.SetDataSource("cp_sr_code", dt0.Rows[0]["cp_sr_code"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sr_code"].ToString());
designer.SetDataSource("cp_st_name", dt0.Rows[0]["cp_st_name"] == DBNull.Value ? "" : dt0.Rows[0]["cp_st_name"].ToString());
designer.SetDataSource("cp_sr_reply_date", dt0.Rows[0]["cp_sr_reply_date"] == DBNull.Value ? "" : dt0.Rows[0]["cp_sr_reply_date"].ToString());
designer.SetDataSource("F_CreatorUserId", dt0.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt0.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("F_CreatorTime", dt0.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt0.Rows[0]["F_CreatorTime"].ToString());
if (dt1.Rows.Count > 0)
{
designer.SetDataSource("d1replyer", dt1.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt1.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d1replytime", dt1.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt1.Rows[0]["F_CreatorTime"].ToString());
}
if (dt2.Rows.Count > 0)
{
designer.SetDataSource("d2replyer", dt2.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt2.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d2replytime", dt2.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt2.Rows[0]["F_CreatorTime"].ToString());
}
if (dt3.Rows.Count > 0)
{
designer.SetDataSource("d3replyer", dt3.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt3.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d3replytime", dt3.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt3.Rows[0]["F_CreatorTime"].ToString());
}
if (dt4.Rows.Count > 0)
{
designer.SetDataSource("d4replyer", dt4.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt4.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d4replytime", dt4.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt4.Rows[0]["F_CreatorTime"].ToString());
}
if (dt5.Rows.Count > 0)
{
designer.SetDataSource("d5replyer", dt5.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt5.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d5replytime", dt5.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt5.Rows[0]["F_CreatorTime"].ToString());
}
if (dt6.Rows.Count > 0)
{
designer.SetDataSource("d6replyer", dt6.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt6.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d6replytime", dt6.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt6.Rows[0]["F_CreatorTime"].ToString());
}
if (dt7.Rows.Count > 0)
{
designer.SetDataSource("d7replyer", dt7.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt7.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d7replytime", dt7.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt7.Rows[0]["F_CreatorTime"].ToString());
}
if (dt8.Rows.Count > 0)
{
designer.SetDataSource("d8replyer", dt8.Rows[0]["F_CreatorUserId"] == DBNull.Value ? "" : dt8.Rows[0]["F_CreatorUserId"].ToString());
designer.SetDataSource("d8replytime", dt8.Rows[0]["F_CreatorTime"] == DBNull.Value ? "" : dt8.Rows[0]["F_CreatorTime"].ToString());
}
}
else
{
}
designer.SetDataSource(dt0);//添加列表数据源
designer.SetDataSource(dt1);//添加列表数据源
designer.SetDataSource(dt2);//添加列表数据源
designer.SetDataSource(dt3);//添加列表数据源
designer.SetDataSource(dt4);//添加列表数据源
designer.SetDataSource(dt5);//添加列表数据源
designer.SetDataSource(dt6);//添加列表数据源
designer.SetDataSource(dt7);//添加列表数据源
designer.SetDataSource(dt8);//添加列表数据源
designer.Process();
string fileName = cp_fbill + "-" + cp_sn + ".zip";
string filePath = Server.MapPath("/Content/cpreport8D/" + fileName);
string sourceDir = Server.MapPath("/Content/cpreport8D/" + cp_fbill + "-" + cp_sn);
if (!Directory.Exists(sourceDir))
{
Directory.CreateDirectory(sourceDir);
}
//string reportex = Server.MapPath("/Content/cpreport8D/" + cp_fbill + "-" + cp_sn + "/") + cp_fbill + "-" + cp_sn + "客诉报告.xlsx";
designer.Save(Server.MapPath("/Content/cpreport8D/" + cp_fbill + "-" + cp_sn + "/") + cp_fbill + "-" + cp_sn + "客诉报告.xlsx", FileFormatType.Excel2007Xlsx);
if (System.IO.File.Exists(filePath))
{
System.IO.File.Delete(filePath);
}
sql = " SELECT*FROM customer_complaint_sp_attach_file WHERE cp_attach_fbill='" + cp_fbill + "' AND cp_attach_sn= " + cp_sn;
DataTable dtfile = DbHelperSQL.Query(sql).Tables[0];
for (int i = 0; i < dtfile.Rows.Count; i++)
{
string dir = Server.MapPath("/Content/cpreport8D/" + cp_fbill + "-" + cp_sn + "/" + dtfile.Rows[i]["cp_attach_type"].ToString());
string fir = Server.MapPath("/Content/cpreport8D/" + cp_fbill + "-" + cp_sn + "/" + dtfile.Rows[i]["cp_attach_type"].ToString() + "/" + dtfile.Rows[i]["F_file_name"].ToString());
if (!Directory.Exists(dir))
{
Directory.CreateDirectory(dir);
}
if (System.IO.File.Exists(fir))
{
System.IO.File.Delete(fir);
}
string sdir = Server.MapPath("/Content/upload/" + dtfile.Rows[i]["F_file_name"].ToString());
using (WebClient webClient = new WebClient())
{
webClient.DownloadFileCompleted += (sender, e) =>
{
// 下载完成后的处理，可以在这里进行文件操作
// 释放资源、关闭文件流等
webClient.Dispose();
};
webClient.DownloadFile(new Uri(dtfile.Rows[i]["cp_attach_path"].ToString()), fir);
}
//// 设置参数
//HttpWebRequest request = WebRequest.Create(dtfile.Rows[i]["cp_attach_path"].ToString()) as HttpWebRequest;
////发送请求并获取相应回应数据
//HttpWebResponse response = request.GetResponse() as HttpWebResponse;
////直到request.GetResponse()程序才开始向目标网页发送Post请求
//Stream responseStream = response.GetResponseStream();
////创建本地文件写入流
//Stream stream = new FileStream(fir, FileMode.Create);
//byte[] bArr = new byte[1024];
//int size = responseStream.Read(bArr, 0, (int)bArr.Length);
//while (size > 0)
//{
// stream.Write(bArr, 0, size);
// size = responseStream.Read(bArr, 0, (int)bArr.Length);
//}
//stream.Close();
//responseStream.Close();
}
ZipUtility.ZipFiles(sourceDir, filePath, "");
return Success("/Content/cpreport8D/" + fileName);
}
#endregion
我在使用WebClient来下载文件到我本地上之后，下载下来的文件没法访问
问题关键代码，用了很多种下载文件的方法，都是下载下来后文件还是被一个进程使用中，没法访问
using (WebClient webClient = new WebClient())
{
webClient.DownloadFileCompleted += (sender, e) =>
{
// 下载完成后的处理，可以在这里进行文件操作
// 释放资源、关闭文件流等
webClient.Dispose();
};
webClient.DownloadFile(new Uri(dtfile.Rows[i]["cp_attach_path"].ToString()), fir);
}
//// 设置参数
//HttpWebRequest request = WebRequest.Create(dtfile.Rows[i]["cp_attach_path"].ToString()) as HttpWebRequest;
////发送请求并获取相应回应数据
//HttpWebResponse response = request.GetResponse() as HttpWebResponse;
////直到request.GetResponse()程序才开始向目标网页发送Post请求
//Stream responseStream = response.GetResponseStream();
////创建本地文件写入流
//Stream stream = new FileStream(fir, FileMode.Create);
//byte[] bArr = new byte[1024];
//int size = responseStream.Read(bArr, 0, (int)bArr.Length);
//while (size > 0)
//{
// stream.Write(bArr, 0, size);
// size = responseStream.Read(bArr, 0, (int)bArr.Length);
//}
//stream.Close();
//responseStream.Close();
后续对下载下来的文件进行访问操作的时候会提示，这个文件被另一进程使用，我来来去去经过排查，应该就是这个webClient 在下载完后，它没有释放出来，但我不知道怎么才可以释放这个webClient
我在代码后面添加过webClient.Dispose（）尝试去释放它，但是加了这个也没用还是同样的提示文件被另一进程使用
使用using (WebClient webClient = new WebClient()){}让他自动释放也不行，也是一样的提示被另一进程使用
后续代码访问这个文件时候，提示的错误
System.IO.IOException:“文件“D:\development230310\seagull.Web\Content\cpreport8D\CP2023080001-1\CP2023080001-1客诉报告.xlsx”正由另一进程使用，因此该进程无法访问此文件。”
在本地文件夹上删除这个文件的时候也会已经打开，没法删除
webClient.DownloadFileAsync
->
webClient.DownloadFile
请
await webClient.DownloadFileTaskAsync(new Uri(dtfile.Rows[i]["cp_attach_path"].ToString()), fir);
既然用异步就请等待他完成，如果你不等待完成就直接在后续操作文件，那么他还在下载中
同时WebClient.DownloadFileTaskAsync 是异步task，你可以直接await他
而你用的DownloadFileAsync是早期的方法，虽然也是异步，不过他的结果通知无法等待，你需要再去订阅完成事件去得到结果
事件为WebClient.DownloadFileCompleted 事件
https://learn.microsoft.com/zh-cn/dotnet/api/system.net.webclient.downloadfilecompleted?view=net-7.0
确保在下载完成后手动释放资源，异步回调中处理释放操作。
using (WebClient webClient = new WebClient())
{
webClient.DownloadFileCompleted += (sender, e) =>
{
// 下载完成后的处理，可以在这里进行文件操作
// 释放资源、关闭文件流等
};
webClient.DownloadFileAsync(new Uri(dtfile.Rows[i]["cp_attach_path"].ToString()), fir);
}