变量"filePath"被声明为btFiles_Click方法的本地变量。为了将其用于其他地方，必须将其声明为代码页的全局：
我有以下代码，我试图通过后台工作程序打开一个目录并处理其中的文件，但我遇到了问题。
我的错误是（名称filePath在当前上下文中不存在），我可以理解，因为它存储在另一个方法中？如果有人能向我指出我的代码有什么问题，我将不胜感激。文件夹浏览器在后台工作程序部分下不起作用。
private void btnFiles_Click(object sender, EventArgs e)
{
//btnFiles.Enabled = false;
btnSTOP.Enabled = true;
//Clear text fields
listBoxResults.Items.Clear();
listBoxPath.Items.Clear();
txtItemsFound.Text = String.Empty;
//Open folder browser for user to select the folder to scan
DialogResult result = folderBrowserDialog1.ShowDialog();
if (result == DialogResult.OK)
{
//Store selected folder path
string filePath = folderBrowserDialog1.SelectedPath;
}
//Start the async operation here
backgroundWorker1.RunWorkerAsync();
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
//Process the folder
try
{
foreach (string dir in Alphaleonis.Win32.Filesystem.Directory.EnumerateFiles(filePath, "*.*", SearchOption.AllDirectories, true))
{
//Populate List Box with all files found
this.Invoke(new Action(() => listUpdate2(dir)));
FileInfo fi = new FileInfo(dir);
if (fi.Length == 0)
{
//Populate List Box with all empty files found
this.Invoke(new Action(() => listUpdate1(dir + Environment.NewLine)));
}
}
}
//Catch exceptions
catch (Exception err)
{
// This code just writes out the message and continues to recurse.
log.Add(err.Message);
//throw;
}
finally
{
//add a count of the empty files here
txtItemsFound.Text = listBoxResults.Items.Count.ToString();
// Write out all the files that could not be processed.
foreach (string s in log)
{
this.Invoke(new Action(() => listUpdate1(s)));
}
log.Clear();
MessageBox.Show("Scanning Complete", "Done", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
}
//If cancel button was pressed while the execution is in progress
//Change the state from cancellation ---> cancelled
if (backgroundWorker1.CancellationPending)
{
e.Cancel = true;
//backgroundWorker1.ReportProgress(0);
return;
}
//}
//Report 100% completion on operation completed
backgroundWorker1.ReportProgress(100);
}
@DonBoitnott解决方案是类内数据流的最通用解决方案。具体到BackgroundWorker，存在另一个
private void btnFiles_Click(object sender, EventArgs e)
{
...
// pass folder name
backgroundWorker1.RunWorkerAsync(folderBrowserDialog1.SelectedPath);
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
// get passed folder name
string filePath = (string)e.Argument;
...
}
public class Form1
{
private String _filePath = null;
private void btnFiles_Click(object sender, EventArgs e)
{
//get your file and assign _filePath here...
_filePath = folderBrowserDialog1.SelectedPath;
}
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
//use _filePath here...
}
}