using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.IO;
using System.Threading;

namespace MultiThread
{
public partial class Form1 : Form
{
public Form1()
        {
            InitializeComponent();
        }

private void button1_Click(object sender, EventArgs e)
        {
using (FolderBrowserDialog fbd = new FolderBrowserDialog())
            {
                fbd.Description = "选择要多线程读取文件的路径";
                fbd.ShowNewFolderButton = false;
if (fbd.ShowDialog(this) == DialogResult.OK)
                {
DirectoryInfo di = new DirectoryInfo(fbd.SelectedPath);
foreach (FileInfo fi in di.GetFiles("*.txt"))
                    {
Thread t = new Thread(this.InvokeThread);
                        t.Start(fi.FullName);
                    }
                }
            }
        }

private delegate void ReadFile(object filePath);

private void InvokeThread(object filePath)
        {
if (this.InvokeRequired)
            {
this.Invoke(new ReadFile(ReadFileContent), filePath);
            }
else
{
                ReadFileContent(filePath);
            }
        }


private void ReadFileContent(object filePath)
        {
this.textBox1.AppendText(File.ReadAllText(filePath.ToString(), Encoding.Default));
this.textBox1.AppendText("\r\n");
        }
    }
}