为什么使用 NPOI 导出 DataTable 到 Excel 会导致 ERR_CONNECTION_RESET
我使用 ASP.NET C# 和 angular 8 开发了一个 Web API。 我尝试将一些数据从 Oracle 导出到服务器端的 Excel 文件中（使用 NPOI），然后在客户端下载。 我可以看到 memoryStream 有数据，但在“返回响应”中它没有返回到客户端，而是再次调用了该函数。 这是我的代码：
HTML：
<button
class="col-sm-2 button-style button-text"
style="color: white; background-color: #19D893;height: 100%;"
(click)="exportPriceList()">
Export
</button>类型脚本：
public exportPriceList(): void {
let fileName='filename';
const fileType = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
console.log('before promise');
const promise = new Promise((resolve, reject) => {
this.export().subscribe(
success => {
console.log('start success');
const blob = new Blob ([success], {type: fileType});
console.log('window.navigator ', window.navigator );
console.log('window.navigator.msSaveOrOpenBlob ', window.navigator.msSaveOrOpenBlob );
if (window.navigator && window.navigator.msSaveOrOpenBlob) {
window.navigator.msSaveOrOpenBlob(blob, );
} else {
const a = document.createElement('a');
a.href = URL.createObjectURL(blob);
a.download = fileName ;
document.body.appendChild(a);
a.click();
document.body.removeChild(a);
}
},
err => {
alert(err);
});
});
promise.then((res) => {
console.log('promise!!!! ', res );
});
promise.catch((err) => {
});
}public export()
{
console.log('start export to excel');
const fileName = 'filename1';
const fileType = 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet';
const url = this.apiService.baseUrl + 'api/PriceList/Export?token=' + this.auth.authDetails.getValue().token +
'&priceListType=' + this.selectedPriceListType.Key + '&fileType=' + fileType + '&bank=' + this.selectedBank.Key;
return this.http.get(url, {responseType: 'arraybuffer'});// this.http.get(url, {responseType: 'blob'});
}API 控制器：
[HttpGet]
[Route("api/PriceList/Export")]
public HttpResponseMessage Export([FromUri]string token, [FromUri]int priceListType,[FromUri]string fileType, [FromUri]int? bank=null)
{
try
{
var stream = dal.ExportPriceListServer(priceListType, bank);
var response = new HttpResponseMessage(System.Net.HttpStatusCode.OK);
response.Content = new StreamContent(stream);
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName= "PriceList_" + bank + "_" + DateTime.Now.ToString("yyyyMMdd") + ".xlsx"
};
response.Content.Headers.ContentType = new MediaTypeHeaderValue(fileType);
return response;
}
catch (Exception ex)
{
exc.throwException(EventLogEntryType.Error, ex.ToString());
throw;
}
}
DAL：（生成 excel 的最终函数。）
public MemoryStream ExportToExcel(DataTable dt)
{
try
{
using (var stream = new MemoryStream())
{
// Declare XSSFWorkbook object for create sheet
var workbook = new XSSFWorkbook();
var sheet = workbook.CreateSheet("sheet 1");
int rowIndex = 0;
var headerRow = sheet.CreateRow(1);
//Below loop is create header
foreach (DataColumn column in dt.Columns)
{
XSSFCell xc = (XSSFCell)headerRow.CreateCell(column.Ordinal);
xc.SetCellValue(GetColumnTitle(column.ColumnName));
//xc.CellStyle = xstl;
}
rowIndex = 2;
foreach (DataRow row in dt.Rows)
{
XSSFRow dataRow = (XSSFRow)(sheet.CreateRow(rowIndex));
foreach (DataColumn column in dt.Columns)
{
XSSFCell c = (XSSFCell)dataRow.CreateCell(column.Ordinal);
string val = row[column].ToString();
int x;
if (Int32.TryParse(val, out x) && (!String.IsNullOrEmpty(val)))//column.IsNumeric()
{
c.SetCellValue(Int64.Parse(val));
c.SetCellType(CellType.Numeric);
}
else
{
c.SetCellValue(row[column].ToString());
}
// no need to auto size all the time, after 100 is ok... (it costs a lot)
if (rowIndex == 100)
{
sheet.AutoSizeColumn(column.Ordinal);
}
}
rowIndex++;
}
// Declare one MemoryStream variable for write file in stream
workbook.Write(stream, true);
return stream;
}
}
catch (Exception ex)
{
Console.Write(ex);
return null;
}
}
这是我在 chrome 调试器中看到的： [Network][1]
在 Timing 中我看到“Stallen”： [Stallen][2]
rates.component.ts:100 before promise zone.js:2969 GET ..... **net::ERR_CONNECTION_RESET** scheduleTask @ zone.js:2969 push../node_modules/zone.js/dist/zone.js.ZoneDelegate.scheduleTask @ zone.js:407 onScheduleTask @ zone.js:297 push../node_modules/zone.js/dist/zone.js.ZoneDelegate.scheduleTask @ zone.js:401 push../node_modules/zone.js/dist/zone.js.Zone.scheduleTask @ zone.js:232 push../node_modules/zone.js/dist/zone.js.Zone.scheduleMacroTask @ zone.js:255 scheduleMacroTaskWithCurrentZone @ zone.js:1114 (anonymous) @ zone.js:3001 proto.<computed> @ zone.js:1394 (anonymous) @ http.js:1630 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable._trySubscribe@ Observable.js:43 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe @ Observable.js:29 push../node_modules/rxjs/_esm5/internal/operators/finalize.js.FinallyOperator.call @ finalize.js:13 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe @ Observable.js:24 (anonymous) @ subscribeTo.js:21 subscribeToResult @ subscribeToResult.js:11 push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._innerSub @ mergeMap.js:74 push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._tryNext @ mergeMap.js:68 push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapSubscriber._next @ mergeMap.js:51 push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next @ Subscriber.js:54 (anonymous) @ scalar.js:5 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable._trySubscribe @ Observable.js:43 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe @ Observable.js:29 push../node_modules/rxjs/_esm5/internal/operators/mergeMap.js.MergeMapOperator.call @ mergeMap.js:29 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe @ Observable.js:24 push../node_modules/rxjs/_esm5/internal/operators/filter.js.FilterOperator.call @ filter.js:15 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe @ Observable.js:24 push../node_modules/rxjs/_esm5/internal/operators/map.js.MapOperator.call @ map.js:18 push../node_modules/rxjs/_esm5/internal/Observable.js.Observable.subscribe @ Observable.js:24 (anonymous) @ rates.component.ts:144 ZoneAwarePromise @ zone.js:891 push../src/app/Components/content/rates/rates.component.ts.RatesComponent.exportPriceList @ rates.component.ts:143 eval @ RatesComponent.html:100 handleEvent @ core.js:19545 callWithDebugContext @ core.js:20639 debugHandleEvent @ core.js:20342 dispatchEvent @ core.js:16994 (anonymous) @ core.js:17441 (anonymous) @ platform-browser.js:993 push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask @ zone.js:421 onInvokeTask @ core.js:14051 push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask @ zone.js:420 push../node_modules/zone.js/dist/zone.js.Zone.runTask @ zone.js:188 push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask @ zone.js:496 invokeTask @ zone.js:1540 globalZoneAwareCallback @ zone.js:1566
您有什么解决方案吗？
谢谢，
我解决了这个问题。 我更改了代码：
API 控制器：
MemoryStream stream = dal.ExportPriceListServer(priceListType);
var response = new HttpResponseMessage(System.Net.HttpStatusCode.OK);
response.Content = new ByteArrayContent(stream.ToArray());
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName = "test.xlsx"
};
response.Content.Headers.ContentType = new MediaTypeHeaderValue(fileType);
return response;
DAL：使用仅用于写入流而包围
// Declare one MemoryStream variable for write file in stream
using (var stream = new MemoryStream())
{
workbook.Write(stream, true);
return stream;
}