How to keep the last used folder and put it in a textbox when a form opens?

问题

When the C# form is loaded, I want to have a folder in a textbox belonging to the user who is logged on by default.

I have textbox and buttons for an input and output file, and when the form is opened I want the user to see the default folder where he saved the previous output file.

How can I do this?

回答1:

Double click on the Settings.settings in the Properties section of the project in the solution explorer.

It opens the parameters wizard containing a grid view.

At bottom, add a parameter named for example LastPath and set it to string type and choose a default value that can be empty.

If you choose to set it empty (recommended), add these variables in the static Program class:

    static string UserDataFolderPath
      = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)
      + Path.DirectorySeparatorChar
      + AssemblyCompany
      + Path.DirectorySeparatorChar
      + AssemblyTitle
      + Path.DirectorySeparatorChar;

    static string UserDocumentsFolderPath
      = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
      + Path.DirectorySeparatorChar
      + AssemblyCompany
      + Path.DirectorySeparatorChar
      + AssemblyTitle
      + Path.DirectorySeparatorChar;

And these methods:

    static public string AssemblyCompany
    {
      get
      {
        object[] attributes = Assembly.GetExecutingAssembly()
                              .GetCustomAttributes(typeof(AssemblyCompanyAttribute), false);
        if ( attributes.Length == 0 )
        {
          return "";
        }
        return ( (AssemblyCompanyAttribute)attributes[0] ).Company;
      }
    }

    static public string AssemblyTitle
    {
      get
      {
        object[] attributes = Assembly.GetExecutingAssembly()
                              .GetCustomAttributes(typeof(AssemblyTitleAttribute), false);
        if ( attributes.Length > 0 )
        {
          AssemblyTitleAttribute titleAttribute = (AssemblyTitleAttribute)attributes[0];
          if ( titleAttribute.Title != "" )
          {
            return titleAttribute.Title;
          }
        }
        return Path.GetFileNameWithoutExtension(Assembly.GetExecutingAssembly().CodeBase);
      }
    }

Add at the beginning of the Main method:

Directory.CreateDirectory(UserDataFolderPath);
Directory.CreateDirectory(UserDocumentsFolderPath);
if ( Properties.Settings.Default.LastPath == "" )
{
  Properties.Settings.Default.LastPath = UserDataFolderPath;
  Properties.Settings.Default.Save();
}

Now to get it you can write in the FormLoad event of your form:

textBox1.Text = Properties.Settings.Default.LastPath;

Put in the FormClosed event:

Properties.Settings.Default.LastPath = textBox1.Text;
Properties.Settings.Default.Save();

Here what should be your Program.cs:

using System;
using System.IO;
using System.Reflection;
using System.Windows.Forms;

namespace WindowsFormsAppTest
{

  static class Program
  {

    [STAThread]
    static void Main()
    {
      Directory.CreateDirectory(UserDataFolderPath);
      Directory.CreateDirectory(UserDocumentsFolderPath);
      if ( Properties.Settings.Default.LastPath == "" )
      {
        Properties.Settings.Default.LastPath = UserDataFolderPath;
        Properties.Settings.Default.Save();
      }
      Application.EnableVisualStyles();
      Application.SetCompatibleTextRenderingDefault(false);
      Application.Run(new FormTest());
    }

    static string UserDataFolderPath
      = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)
      + Path.DirectorySeparatorChar
      + AssemblyCompany
      + Path.DirectorySeparatorChar
      + AssemblyTitle
      + Path.DirectorySeparatorChar;

    static string UserDocumentsFolderPath
      = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
      + Path.DirectorySeparatorChar
      + AssemblyCompany
      + Path.DirectorySeparatorChar
      + AssemblyTitle
      + Path.DirectorySeparatorChar;

    static public string AssemblyCompany
    {
      get
      {
        object[] attributes = Assembly.GetExecutingAssembly()
                              .GetCustomAttributes(typeof(AssemblyCompanyAttribute), false);
        if ( attributes.Length == 0 )
        {
          return "";
        }
        return ( (AssemblyCompanyAttribute)attributes[0] ).Company;
      }
    }

    static public string AssemblyTitle
    {
      get
      {
        object[] attributes = Assembly.GetExecutingAssembly()
                              .GetCustomAttributes(typeof(AssemblyTitleAttribute), false);
        if ( attributes.Length > 0 )
        {
          AssemblyTitleAttribute titleAttribute = (AssemblyTitleAttribute)attributes[0];
          if ( titleAttribute.Title != "" )
          {
            return titleAttribute.Title;
          }
        }
        return Path.GetFileNameWithoutExtension(Assembly.GetExecutingAssembly().CodeBase);
      }
    }

  }

}

And your Form.cs:

using System;
using System.Windows.Forms;

namespace WindowsFormsAppTest
{

  public partial class FormTest : Form
  {

    public FormTest()
    {
      InitializeComponent();
    }

    private void FormTest_Load(object sender, EventArgs e)
    {
      textBox1.Text = Properties.Settings.Default.LastPath;
    }

    private void FormTest_FormClosed(object sender, FormClosedEventArgs e)
    {
      Properties.Settings.Default.LastPath = textBox1.Text;
      Properties.Settings.Default.Save();
    }

  }

}

来源：https://stackoverflow.com/questions/58202091/how-to-keep-the-last-used-folder-and-put-it-in-a-textbox-when-a-form-opens