ADO.NET连接池的建立[转]

此示例阐释如何建立到数据源的连接池。需要进行此操作来部署高性能的应用程序。在此示例中，池是在连接字符串中建立起来，并由 SqlConnection 自动管理的。
　

以下是用C#编写的代码 connectionpooling.cs

namespace HowTo.Samples.ADONET
{

using System;
using System.Data.SqlClient;

public class connectionpooling
{
public static void Main()
{
connectionpooling myconnectionpooling = new connectionpooling();
myconnectionpooling.Run();
}

public void Run()
{
try
{
String connString;

// Specification in the connection string:
// Please note: Pooling is implicit, you automatically get it unless you disable it.
// Therefore, "true" is the default for the pooling keyword (pooling=true).
// Connection Reset: False
// Connection Lifetime: 5
// Enlist: true
// Min Pool Size: 1
// Max Pool Size: 50
connString = "server=(local)\\NetSDK;Trusted_Connection=yes;database=northwind;" +
"connection reset=false;" +
"connection lifetime=5;" +
"min pool size=1;" +
"max pool size=50";

SqlConnection myConnection1 = new SqlConnection(connString);
SqlConnection myConnection2 = new SqlConnection(connString);
SqlConnection myConnection3 = new SqlConnection(connString);

// Open two connections.
Console.WriteLine ("打开两个连接。");
myConnection1.Open();
myConnection2.Open();

// Now there are two connections in the pool that matches the connection string.
// Return the both connections to the pool.
Console.WriteLine ("将两个连接都返回到池中。");
myConnection1.Close();
myConnection2.Close();

// Get a connection out of the pool.
Console.WriteLine ("从池中打开一个连接。");
myConnection1.Open();

// Get a second connection out of the pool.
Console.WriteLine ("从池中打开第二个连接。");
myConnection2.Open();

// Open a third connection.
Console.WriteLine ("打开第三个连接。");
myConnection3.Open();

// Return the all connections to the pool.
Console.WriteLine ("将所有三个连接都返回到池中。");
myConnection1.Close();
myConnection2.Close();
myConnection3.Close();
}
catch (Exception e)
{
// Display the error.
Console.WriteLine(e.ToString());
}
}
}

}

以下是用C#编写的ASP.NET代码 connectionpooling.aspx

<%@ Page Language="C#" Debug="true" Src="connectionpooling.cs"%>
<%@ Import Namespace="System.IO" %>

<%@ Import Namespace="HowTo.Samples.ADONET" %>

protected void Page_Load(Object Src, EventArgs E)
{
StringWriter writer = new StringWriter();
Console.SetOut(writer);
connectionpooling myconnectionpooling = new connectionpooling();
myconnectionpooling.Run();
output.InnerHtml = writer.ToString();
}

</script>

在此示例中，在构造 SqlConnection 时在连接字符串中指定池特性，如以下的代码示例中所示。请注意：池处理是隐式的，除非将其禁用，否则将自动进行池处理。因此，"true"是默认的池关键词 (pooling=true)。

String connString;

connString = "server=(local)\\VSdotNET;Trusted_Connection=yes;database=northwind;" +
"connection reset=false;" +
"connection lifetime=5;" +
"min pool size=1;" +
"max pool size=50";

SqlConnection myConnection1 = new SqlConnection(connString);
SqlConnection myConnection2 = new SqlConnection(connString);
SqlConnection myConnection3 = new SqlConnection(connString);

Dim connString as String

' Specification in the connection string:
' Please note: Pooling is implicit, you automatically get it unless you disable it.
' Therefore, "true" is the default for the pooling keyword (pooling=true).
' Connection Reset: False
' Connection Lifetime: 5
' Enlist: true
' Min Pool Size: 1
' Max Pool Size: 50

connString = "server=(local)\VSdotNET;Trusted_Connection=yes;database=northwind;" & _
"connection reset=false;" & _
"connection lifetime=5;" & _
"enlist=true;" & _
"min pool size=1;" & _
"max pool size=50"

Dim myConnection1 as SqlConnection = new SqlConnection(connString)
Dim myConnection2 as SqlConnection = new SqlConnection(connString)
Dim myConnection3 as SqlConnection = new SqlConnection(connString)

现在，我们有了使用池中的若干连接的代码。首先，打开两个连接并返回这两个到池的连接。然后，从池中打开三个连接，并返回所有这三个到池的连接。

// Open two connections. One is from the pool (see min pool size), the other is created.
Console.WriteLine ("Open two connections.");
myConnection1.Open();
myConnection2.Open();

// Now there are two connections in the pool that matches the connection string.
// Return the both connections to the pool.
Console.WriteLine ("Return both of the connections to the pool.");
myConnection1.Close();
myConnection2.Close();

// Get a connection out of the pool.
Console.WriteLine ("Open a connection from the pool.");
myConnection1.Open();

// Get a second connection out of the pool.
Console.WriteLine ("Open a second connection from the pool.");
myConnection2.Open();

// Open a third connection.
Console.WriteLine ("Open a third connection.");
myConnection3.Open();

// Return the all connections to the pool.
Console.WriteLine ("Return all three connections to the pool.");
myConnection1.Close();
myConnection2.Close();
myConnection3.Close();

池连接的模型与非池连接的相似。但是，当断开池连接来将其释放回池时，调用 Close 是特别重要的。

posted on 2005-08-20 13:53 rockerychn 阅读(658) 评论(1) 编辑收藏举报

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