网络编程ASP.NET的几个技巧

1.显示通过代码生成的图片

把生成图片的代码放在一个aspx页面中，在PageLoad事件中把图片写入输出流：
private void Page_Load(object sender, System.EventArgs e) {
    string code = Request.Params["code"];
    Bitmap image = DrawImage(code);
    Response.ContentType = "image/gif";
    image.Save(Response.OutputStream,System.Drawing.Imaging.ImageFormat.Gif);
    Response.End();
}

在需要引用图片的地方，设定图片URL为生成图片的aspx页面：
ImageCode.ImageUrl = "CodeImage.aspx?code="+code;

2.使用System.Web.HttpContext.Current来实现一些页面中常用的方法，比如：
public class WebApp{
public static void ShowMessage(string message){
    HttpContext.Current.Response.Write ("<script language=javascript>alert('"+message+"')</script>");
}
public static string CurrentUser{
    get{
        return HttpContext.Current.Session["UserID"]+"";
    }
}
}

3.在自定义的Web控件中，把Javascript脚本文件编译为内嵌的资源，然后从资源中读取脚本并注册。

public class Res {
    public static StreamReader GetStream(Type type,string name){
        //Assembly assembly = Assembly.GetAssembly(type);
        Assembly assembly = type.Assembly;
        Stream stream = assembly.GetManifestResourceStream(type,name);
        return new StreamReader(stream);
    }
}

public class ScriptControl : Control {

    /// <summary>
    /// Register Client Script Block
    /// </summary>
    /// <param name="control">custom web control</param>
    /// <param name="scriptfile">resource script file name</param>
    public void RegisterScript(string scriptfile){
        if (!this.Page.IsClientScriptBlockRegistered(scriptfile)) {
            StreamReader reader = Res.GetStream(this.GetType(),scriptfile);
            using(reader){
                string script
                    = "<script language=\"javascript\" type=\"text/javascript\">\r\n<!--\r\n"
                    + reader.ReadToEnd()
                    + "\r\n//-->\r\n</script>";
                this.Page.RegisterClientScriptBlock(scriptfile, script);
            }
        }
    }
}

[DefaultProperty("Text"),
ToolboxData("<{0}:ShowDialogListBox runat=server></{0}:ShowDialogListBox>")]
public class ShowDialogListBox : ScriptControl {
    ......
    protected override void OnInit(EventArgs e) {
        this.RegisterScript("EnDeListBox.js");
    }
    ......
}

4.在web.config文件中定义默认的页面继承类型。

<pages pageBaseType="Msdn.Page" />