asp.net response.ContentType 下载文件的四种方法

protected void Button1_Click(object sender, EventArgs e)
{

protected void Button1_Click(object sender, EventArgs e)
2 protected void Button2_Click(object sender, EventArgs e)
protected void Button3_Click(object sender, EventArgs e)

//字符流方式下载文件
protected void Button4_Click(object sender, EventArgs e)
{
string fileName = "ce2.rar";//客户端保存的文件名
string filePath = Server.MapPath("keji.rar");//路径

//以字符流的形式下载文件
FileStream fs = new FileStream(filePath, FileMode.Open);
byte[] bytes = new byte[(int)fs.Length];
fs.Read(bytes, 0, bytes.Length);
fs.Close();
Response.ContentType = "application/octet-stream";
//通知浏览器下载文件而不是打开
Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
Response.BinaryWrite(bytes);
Response.Flush();
Response.End();

}