C# 在新任务中生成文件而不阻塞UI并处理异常
我正在尝试构建生成Crystal Reports文件的.NET4.0应用程序。 我有一个工作版本,但一切都是同步工作的-在我单击“生成”按钮后,应用程序将冻结5秒钟。C# 在新任务中生成文件而不阻塞UI并处理异常,c#,.net-4.0,crystal-reports,task-parallel-library,task,C#,.net 4.0,Crystal Reports,Task Parallel Library,Task,我正在尝试构建生成Crystal Reports文件的.NET4.0应用程序。 我有一个工作版本,但一切都是同步工作的-在我单击“生成”按钮后,应用程序将冻结5秒钟。 相反,我想显示一个进度指示器,表明文件正在生成,但我的代码有问题 生成报告的方法如下所示: public static Task<string> GenerateLetter() { const string destinationLocation = @"C:\Export"; const strin
相反,我想显示一个进度指示器,表明文件正在生成,但我的代码有问题 生成报告的方法如下所示:
public static Task<string> GenerateLetter()
{
const string destinationLocation = @"C:\Export";
const string source = @"C:\Test_Report.rpt";
return Task<string>.Factory.StartNew(() =>
{
if (File.Exists(source))
{
var crReportDocument = new ReportDocument();
crReportDocument.Load(source);
var destinationFolder = new DirectoryInfo(destinationLocation);
if (!destinationFolder.Exists)
destinationFolder.Create();
var timeStamp = DateTime.Now.ToString().Replace(":", "").Replace(" ", "").Replace("-", "");
var destination = Path.Combine(destinationFolder.FullName, timeStamp + ".pdf");
var crDiskFileDestinationOptions = new DiskFileDestinationOptions { DiskFileName = destination };
var crExportOptions = crReportDocument.ExportOptions;
{
crExportOptions.DestinationOptions = crDiskFileDestinationOptions;
crExportOptions.ExportDestinationType = ExportDestinationType.DiskFile;
crExportOptions.ExportFormatType = ExportFormatType.PortableDocFormat;
}
try
{
crReportDocument.Export();
return destination;
}
catch (Exception ex)
{
throw new SystemException("Error exporting!", ex);
}
}
throw new FileNotFoundException("Report file not found!", source);
});
}
Task<string>.Factory.StartNew(() =>
{
// Your logic here
}, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default)
.ContinueWith((p) =>
{
// This will be UI thread
// p is the parent task
progressBar1.Visible = false;
// if parent task has faulted
if (p.IsFaulted)
{
// Do with p.Exception field what ever you want - log it, show it.
// for .net 4.0 you must read this property in order to prevent
// application failure
MessageBox.Show(p.Exception.Message);
return;
}
// Here you know all about the parent task, so you can do the logic you want:
MessageBox.Show(p.Result);
}, TaskScheduler.FromCurrentSynchronizationContext());
公共静态任务生成器()
{
常量字符串destinationLocation=@“C:\Export”;
常量字符串源=@“C:\Test_Report.rpt”;
返回Task.Factory.StartNew(()=>
{
if(File.Exists(source))
{
var crReportDocument=新报告文档();
crReportDocument.Load(源);
var destinationFolder=新目录信息(destinationLocation);
如果(!destinationFolder.Exists)
destinationFolder.Create();
var timeStamp=DateTime.Now.ToString().Replace(“:”,”).Replace(“,”).Replace(“-”,”);
var destination=Path.Combine(destinationFolder.FullName,timeStamp+“.pdf”);
var crDiskFileDestinationOptions=new DiskFileDestinationOptions{DiskFileName=destination};
var crExportOptions=crReportDocument.ExportOptions;
{
crExportOptions.DestinationOptions=crDiskFileDestinationOptions;
crExportOptions.ExportDestinationType=ExportDestinationType.DiskFile;
crExportOptions.ExportFormatType=ExportFormatType.PortableDocFormat;
}
尝试
{
crReportDocument.Export();
返回目的地;
}
捕获(例外情况除外)
{
抛出新的系统异常(“导出错误!”,ex);
}
}
抛出新的FileNotFoundException(“未找到报告文件!”,源);
});
}
方法返回生成文件的本地化,或者在出现问题时抛出异常
在我的表格中,我放置了一个按钮和一个字幕进度条。我已将此处理程序附加到按钮的单击:
private void button1_Click(object sender, EventArgs e)
{
progressBar1.Visible = true;
try
{
Task<string> xx = ReportGenerator.GenerateLetter();
MessageBox.Show(xx.Result);
progressBar1.Visible = false;
}
catch (AggregateException ae)
{
ae.Handle(x =>
{
if (x is FileNotFoundException)
{
var ex = x as FileNotFoundException;
MessageBox.Show(ex.Message,"File not found");
progressBar1.Visible = false;
}
else if (x is SystemException)
{
var ex = x as SystemException;
MessageBox.Show(ex.Message,"Other exception");
progressBar1.Visible = false;
}
return true;
});
}
}
private void按钮1\u单击(对象发送者,事件参数e)
{
progressBar1.Visible=true;
尝试
{
任务xx=ReportGenerator.GenerateLetter();
MessageBox.Show(xx.Result);
progressBar1.Visible=false;
}
捕获(聚合异常ae)
{
ae.Handle(x=>
{
如果(x是FileNotFoundException)
{
var ex=x作为FileNotFoundException;
Show(例如Message,“未找到文件”);
progressBar1.Visible=false;
}
else if(x是系统异常)
{
var ex=x作为系统异常;
MessageBox.Show(例如Message,“其他异常”);
progressBar1.Visible=false;
}
返回true;
});
}
}
我的问题是:
Task.Result
正在阻止调用,因此您的UI线程将冻结,直到任务完成。
解决此问题的方法是使用新的异步
/等待
功能。即使在.NET4.0中也可以使用它,但需要包括
使事件处理程序方法异步并“等待”任务
private async void button1_Click(object sender, EventArgs e)
{
progressBar1.Visible = true;
try
{
string result =await ReportGenerator.GenerateLetter();
MessageBox.Show(result);
progressBar1.Visible = false;
}
catch{
........
}
Task.Result
正在阻止调用,因此您的UI线程将冻结,直到任务完成。
解决此问题的方法是使用新的异步
/等待
功能。即使在.NET4.0中也可以使用它,但需要包括
使事件处理程序方法异步并“等待”任务
private async void button1_Click(object sender, EventArgs e)
{
progressBar1.Visible = true;
try
{
string result =await ReportGenerator.GenerateLetter();
MessageBox.Show(result);
progressBar1.Visible = false;
}
catch{
........
}
这是一个很好的开始
您可以在4.0和4.5.NETFramework中使用它们
为了确保TPL任务在线程上运行,与UI线程不同,您应该使用(例如,查看)
所以你应该这样做:
public static Task<string> GenerateLetter()
{
const string destinationLocation = @"C:\Export";
const string source = @"C:\Test_Report.rpt";
return Task<string>.Factory.StartNew(() =>
{
if (File.Exists(source))
{
var crReportDocument = new ReportDocument();
crReportDocument.Load(source);
var destinationFolder = new DirectoryInfo(destinationLocation);
if (!destinationFolder.Exists)
destinationFolder.Create();
var timeStamp = DateTime.Now.ToString().Replace(":", "").Replace(" ", "").Replace("-", "");
var destination = Path.Combine(destinationFolder.FullName, timeStamp + ".pdf");
var crDiskFileDestinationOptions = new DiskFileDestinationOptions { DiskFileName = destination };
var crExportOptions = crReportDocument.ExportOptions;
{
crExportOptions.DestinationOptions = crDiskFileDestinationOptions;
crExportOptions.ExportDestinationType = ExportDestinationType.DiskFile;
crExportOptions.ExportFormatType = ExportFormatType.PortableDocFormat;
}
try
{
crReportDocument.Export();
return destination;
}
catch (Exception ex)
{
throw new SystemException("Error exporting!", ex);
}
}
throw new FileNotFoundException("Report file not found!", source);
});
}
Task<string>.Factory.StartNew(() =>
{
// Your logic here
}, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default)
.ContinueWith((p) =>
{
// This will be UI thread
// p is the parent task
progressBar1.Visible = false;
// if parent task has faulted
if (p.IsFaulted)
{
// Do with p.Exception field what ever you want - log it, show it.
// for .net 4.0 you must read this property in order to prevent
// application failure
MessageBox.Show(p.Exception.Message);
return;
}
// Here you know all about the parent task, so you can do the logic you want:
MessageBox.Show(p.Result);
}, TaskScheduler.FromCurrentSynchronizationContext());
Task.Factory.StartNew(()=>
{
//你的逻辑在这里
},CancellationToken.None,TaskCreationOptions.None,TaskScheduler.Default)
.ContinueWith((p)=>
{
//这将是UI线程
//p是父任务
progressBar1.Visible=false;
//如果父任务出现故障
如果(p.IsFaulted)
{
//对p.Exception字段执行任何您想要的操作-记录它,显示它。
//对于.net 4.0,必须读取此属性才能防止
//应用程序失败
MessageBox.Show(p.Exception.Message);
返回;
}
//在这里,您了解有关父任务的所有信息,因此可以执行所需的逻辑:
MessageBox.Show(p.Result);
},TaskScheduler.FromCurrentSynchronizationContext());
由于此参数,将在UI线程上执行延续任务
在.NET4.0中,您还必须处理延续任务中的异常。例如,您可以使用try-catch-block来执行此操作。是一个很好的起点
您可以在4.0和4.5.NETFramework中使用它们
为了确保TPL任务在线程上运行,与UI线程不同,您应该使用(例如,查看)
所以你应该这样做:
public static Task<string> GenerateLetter()
{
const string destinationLocation = @"C:\Export";
const string source = @"C:\Test_Report.rpt";
return Task<string>.Factory.StartNew(() =>
{
if (File.Exists(source))
{
var crReportDocument = new ReportDocument();
crReportDocument.Load(source);
var destinationFolder = new DirectoryInfo(destinationLocation);
if (!destinationFolder.Exists)
destinationFolder.Create();
var timeStamp = DateTime.Now.ToString().Replace(":", "").Replace(" ", "").Replace("-", "");
var destination = Path.Combine(destinationFolder.FullName, timeStamp + ".pdf");
var crDiskFileDestinationOptions = new DiskFileDestinationOptions { DiskFileName = destination };
var crExportOptions = crReportDocument.ExportOptions;
{
crExportOptions.DestinationOptions = crDiskFileDestinationOptions;
crExportOptions.ExportDestinationType = ExportDestinationType.DiskFile;
crExportOptions.ExportFormatType = ExportFormatType.PortableDocFormat;
}
try
{
crReportDocument.Export();
return destination;
}
catch (Exception ex)
{
throw new SystemException("Error exporting!", ex);
}
}
throw new FileNotFoundException("Report file not found!", source);
});
}
Task<string>.Factory.StartNew(() =>
{
// Your logic here
}, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.Default)
.ContinueWith((p) =>
{
// This will be UI thread
// p is the parent task
progressBar1.Visible = false;
// if parent task has faulted
if (p.IsFaulted)
{
// Do with p.Exception field what ever you want - log it, show it.
// for .net 4.0 you must read this property in order to prevent
// application failure
MessageBox.Show(p.Exception.Message);
return;
}
// Here you know all about the parent task, so you can do the logic you want:
MessageBox.Show(p.Result);
}, TaskScheduler.FromCurrentSynchronizationContext());
Task.Factory.StartNew(()=>
{
//你的逻辑在这里
},CancellationToken.None,TaskCreationOptions.None,TaskScheduler.Default)
.ContinueWith((p)=>
{
//这将是UI线程
//p是父任务
progressBar1.Visible=false;
//如果父任务出现故障
如果(p.IsFaulted)
{
//对p.Exception字段执行任何您想要的操作-记录它,显示它。
//对于.net 4.0,必须在中读取此属性