示例1.演示异步获取一个网址的内容，处理后显示在OutPut这一Label上
1
using
System;
2
using
System.Web;
3
using
System.Web.UI;
4
using
System.Web.UI.WebControls;
5
using
System.Net;
6
using
System.IO;
7
using
System.Text;
8
using
System.Text.RegularExpressions;
9
10
public
partial
class
AsyncPage : System.Web.UI.Page
11
{
12
private WebRequest _request;
13
14 void Page_Load (object sender, EventArgs e)
15
{
16 AddOnPreRenderCompleteAsync (
17 new BeginEventHandler(BeginAsyncOperation),
18 new EndEventHandler (EndAsyncOperation)
19 );
20
}
21
22 IAsyncResult BeginAsyncOperation (object sender, EventArgs e,
23 AsyncCallback cb, object state)
24 {
25 _request = WebRequest.Create("http://msdn.microsoft.com");
26 return _request.BeginGetResponse (cb, state);
27 }
28 void EndAsyncOperation (IAsyncResult ar)
29 {
30 string text;
31 using (WebResponse response = _request.EndGetResponse(ar))
32 {
33 using (StreamReader reader =
34 new StreamReader(response.GetResponseStream()))
35 {
36 text = reader.ReadToEnd();
37 }
38 }
39
40 Regex regex = new Regex ("href\\s*=\\s*\"([^\"]*)\"",
41 RegexOptions.IgnoreCase);
42 MatchCollection matches = regex.Matches(text);
43
44 StringBuilder builder = new StringBuilder(1024);
45 foreach (Match match in matches)
46 {
47 builder.Append (match.Groups[1]);
48 builder.Append("<br/>");
49 }
50
51 Output.Text = builder.ToString ();
52 }
53
}
54
55
using
System;2
using
System.Web;3
using
System.Web.UI;4
using
System.Web.UI.WebControls;5
using
System.Net;6
using
System.IO;7
using
System.Text;8
using
System.Text.RegularExpressions;9
10
public
partial
class
AsyncPage : System.Web.UI.Page11
{
12
private WebRequest _request;13
14
void Page_Load (object sender, EventArgs e)15
{16
AddOnPreRenderCompleteAsync (17
new BeginEventHandler(BeginAsyncOperation),18
new EndEventHandler (EndAsyncOperation)19
);20
}21
22
IAsyncResult BeginAsyncOperation (object sender, EventArgs e, 23
AsyncCallback cb, object state)24
{25
_request = WebRequest.Create("http://msdn.microsoft.com");26
return _request.BeginGetResponse (cb, state);27
}28
void EndAsyncOperation (IAsyncResult ar)29
{30
string text;31
using (WebResponse response = _request.EndGetResponse(ar))32
{33
using (StreamReader reader = 34
new StreamReader(response.GetResponseStream()))35
{36
text = reader.ReadToEnd();37
}38
}39
40
Regex regex = new Regex ("href\\s*=\\s*\"([^\"]*)\"", 41
RegexOptions.IgnoreCase);42
MatchCollection matches = regex.Matches(text);43
44
StringBuilder builder = new StringBuilder(1024);45
foreach (Match match in matches)46
{47
builder.Append (match.Groups[1]);48
builder.Append("<br/>");49
}50
51
Output.Text = builder.ToString ();52
}53
}
54
55
示例2:演示如何异步从数据库查询数据，并将返回的DataReader绑定到指定控件上
using
System;
using
System.Data;
using
System.Data.SqlClient;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
using
System.Web.Configuration;
public
partial
class
AsyncDataBind : System.Web.UI.Page
{ private SqlConnection _connection; private SqlCommand _command; private SqlDataReader _reader; protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { // Hook PreRenderComplete event for data binding this.PreRenderComplete += new EventHandler(Page_PreRenderComplete); // Register async methods AddOnPreRenderCompleteAsync( new BeginEventHandler(BeginAsyncOperation), new EndEventHandler(EndAsyncOperation) ); } } IAsyncResult BeginAsyncOperation (object sender, EventArgs e, AsyncCallback cb, object state) { string connect = WebConfigurationManager.ConnectionStrings ["PubsConnectionString"].ConnectionString; _connection = new SqlConnection(connect); _connection.Open(); _command = new SqlCommand( "SELECT title_id, title, price FROM titles", _connection); return _command.BeginExecuteReader (cb, state); } void EndAsyncOperation(IAsyncResult ar) { _reader = _command.EndExecuteReader(ar); } protected void Page_PreRenderComplete(object sender, EventArgs e) { Output.DataSource = _reader; Output.DataBind(); } public override void Dispose() { if (_connection != null) _connection.Close(); base.Dispose(); }}
示例3:异步调用WebService
using
System;
using
System.Data;
using
System.Configuration;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
public
partial
class
AsyncWSInvoke1 : System.Web.UI.Page
{ private WS.PubsWebService _ws; private DataSet _ds; protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { // Hook PreRenderComplete event for data binding this.PreRenderComplete += new EventHandler(Page_PreRenderComplete); // Register async methods AddOnPreRenderCompleteAsync( new BeginEventHandler(BeginAsyncOperation), new EndEventHandler(EndAsyncOperation) ); } } IAsyncResult BeginAsyncOperation (object sender, EventArgs e, AsyncCallback cb, object state) { _ws = new WS.PubsWebService(); // Fix up URL for call to local VWD-hosted Web service _ws.Url = new Uri(Request.Url, "Pubs.asmx").ToString(); _ws.UseDefaultCredentials = true; return _ws.BeginGetTitles (cb, state); } void EndAsyncOperation(IAsyncResult ar) { _ds = _ws.EndGetTitles(ar); } protected void Page_PreRenderComplete(object sender, EventArgs e) { Output.DataSource = _ds; Output.DataBind(); } public override void Dispose() { if (_ws != null) _ws.Dispose(); base.Dispose(); }}
示例4:还是异步调用WebService,但换了一种方法
using
System;
using
System.Data;
using
System.Configuration;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
public
partial
class
AsyncWSInvoke2 : System.Web.UI.Page
{ private WS.PubsWebService _ws; private DataSet _ds; protected void Page_Load(object sender, EventArgs e) { if (!IsPostBack) { // Hook PreRenderComplete event for data binding this.PreRenderComplete += new EventHandler(Page_PreRenderComplete); // Call the Web service asynchronously _ws = new WS.PubsWebService(); _ws.GetTitlesCompleted += new WS.GetTitlesCompletedEventHandler(GetTitlesCompleted); _ws.Url = new Uri(Request.Url, "Pubs.asmx").ToString(); _ws.UseDefaultCredentials = true; _ws.GetTitlesAsync(); } } void GetTitlesCompleted(Object source, WS.GetTitlesCompletedEventArgs e) { _ds = e.Result; } protected void Page_PreRenderComplete(object sender, EventArgs e) { Output.DataSource = _ds; Output.DataBind(); } public override void Dispose() { if (_ws != null) _ws.Dispose(); base.Dispose(); }}
示例5：跟示例1差不多，但是加了TimeOut处理
using
System;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
using
System.Net;
using
System.IO;
using
System.Text;
using
System.Text.RegularExpressions;
public
partial
class
AsyncPageTask : System.Web.UI.Page
{ private WebRequest _request; protected void Page_Load(object sender, EventArgs e) { PageAsyncTask task = new PageAsyncTask( new BeginEventHandler(BeginAsyncOperation), new EndEventHandler(EndAsyncOperation), new EndEventHandler(TimeoutAsyncOperation), null ); RegisterAsyncTask(task); } IAsyncResult BeginAsyncOperation(object sender, EventArgs e, AsyncCallback cb, object state) { _request = WebRequest.Create("http://msdn.microsoft.com"); return _request.BeginGetResponse(cb, state); } void EndAsyncOperation(IAsyncResult ar) { string text; using (WebResponse response = _request.EndGetResponse(ar)) { using (StreamReader reader = new StreamReader(response.GetResponseStream())) { text = reader.ReadToEnd(); } } Regex regex = new Regex("href\\s*=\\s*\"([^\"]*)\"", RegexOptions.IgnoreCase); MatchCollection matches = regex.Matches(text); StringBuilder builder = new StringBuilder(1024); foreach (Match match in matches) { builder.Append(match.Groups[1]); builder.Append("<br/>"); } Output.Text = builder.ToString(); } void TimeoutAsyncOperation(IAsyncResult ar) { Output.Text = "Data temporarily unavailable"; }}
