asp.net导出Excel乱码的原因及解决方法

protected void Excel_Click(object sender, EventArgs e)
{
Response.Charset = "UTF-8";
Response.ClearContent();
Response.Clear();
Response.ContentEncoding = System.Text.Encoding.UTF8;
Response.HeaderEncoding = System.Text.Encoding.UTF8;
Response.AddHeader("content-disposition", "attachment; filename=MyExpress.xls");
Response.ContentType = "application/excel";
System.IO.StringWriter sw = new System.IO.StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
// turn off paging
GridView1.AllowPaging = false;
dataBind();
GridView1.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();
// turn the paging on again
GridView1.AllowPaging = true;
dataBind();
}

Response.Charset = "UTF-8";//添加编码格式
Response.ClearContent();
Response.Clear();
Response.ContentEncoding = System.Text.Encoding.UTF8;//表格内容添加编码格式
Response.HeaderEncoding = System.Text.Encoding.UTF8;//表头添加编码格式

Response.ClearContent();
Response.Clear();
Response.AddHeader("content-disposition", "attachment; filename=sumlate.xls");
Response.Charset = "GB2312";
Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
Response.ContentType = "application/excel";
System.IO.StringWriter sw = new System.IO.StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);
if (GridView2.Rows.Count > 0)
{
GridView2.RenderControl(htw);
}
else
{
GridView1.RenderControl(htw);
}
Response.Write(sw.ToString());
Response.End();

Response.Charset = "GB2312";
Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");