private void button3_Click(object sender, EventArgs e)
{
string SourceFilePath = @textBox1.Text;
string name = Path.GetFileName(SourceFilePath);
string OutFile = @"./解密后的文件/decrypt-" + name; //组装新名字
Encrypt decrypt = new Encrypt(EncryptClass.DecryptDES);
decrypt.BeginInvoke(SourceFilePath, OutFile, "12345678", new AsyncCallback(decryptCompleted), null);
labelState.Text = "开始解密，请稍等";
}