using System;
using System.Collections.Generic;
using System.Text;
using System.Configuration;
using System.Configuration.Provider;
using System.Drawing;
namespace ps
{
public abstract class ImageProvider : ProviderBase
{
public abstract Image ShowImg(string id);
}
}
ImageProviderCollection类，ImageProvider类的集合
using System;
using System.Collections.Generic;
using System.Text;
using System.Configuration;
using System.Configuration.Provider;
namespace ps
{
public class ImageProviderCollection:ProviderCollection
{
public new ImageProvider this[string name]
{
get
{
return (ImageProvider)base[name];
}
}
public override void Add(ProviderBase provider)
{
if (provider == null)
{
throw new ArgumentNullException("provider is null");
}
if (!(provider is ImageProvider))
{
throw new ArgumentException("provider is not imageprovider");
}
base.Add(provider);
}
}
}
ImageServiceSection类，实现自己的Section
using System;
using System.Collections.Generic;
using System.Text;
using System.Configuration;
using System.Configuration.Provider;
namespace ps
{
public class ImageServiceSection:ConfigurationSection
{
[ConfigurationProperty("myp")]
public ProviderSettingsCollection provider
{
get
{
return (ProviderSettingsCollection)base["myp"];
}
}
[StringValidator(MinLength = 1)]
[ConfigurationProperty("defaultProvider", DefaultValue = "SqlImageProvider")]
public string defaultProvider
{
get
{
return (string)base["defaultProvider"];
}
set
{
base["defaultProvider"] = value;
}
}
}
}
SqlImg类，具体实现自己的工作
using System;
using System.Collections.Generic;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
namespace ps
{
public class SqlImg : ImageProvider
{
private string _constr;
public override Image ShowImg(string id)
{
System.Data.SqlClient.SqlConnection conn = new SqlConnection(_constr);
string sql = "select url from img where id =" + id;
System.Data.SqlClient.SqlCommand cmd = new SqlCommand(sql, conn);
cmd.Connection.Open();
//cmd.ExecuteScalar();
System.Data.SqlClient.SqlDataReader read = cmd.ExecuteReader();
if (read.Read())
{
string url = read[0].ToString();
System.Drawing.Bitmap bmp = new System.Drawing.Bitmap(url);
return (System.Drawing.Image)bmp;
}
else
{
return null;
}
//throw new Exception("The method or operation is not implemented.");
}
public override void Initialize(string name, System.Collections.Specialized.NameValueCollection config)
{
base.Initialize(name, config);
string connfig = config["sqlconstr"];
_constr = System.Configuration.ConfigurationManager.ConnectionStrings[connfig].ConnectionString;
}
}
}
ImageService类，对自己实现的sqlimg进行调用
using System;
using System.Collections.Generic;
using System.Text;
using System.Configuration;
using System.Configuration.Provider;
using System.Drawing;
using System.Drawing.Imaging;
namespace ps
{
public class ImageService
{
private static ImageProvider _ip;
private static ImageProviderCollection _ipc;
private static object _obj = new object();
public static ImageProvider ip
{
get
{
loadprovider();
return _ip;
}
}
private static void loadprovider()
{
if (_ipc == null)
{
lock (_obj)
{
ImageServiceSection section = (ImageServiceSection)ConfigurationManager.GetSection("testmy");
_ipc = new ImageProviderCollection();
System.Web.Configuration.ProvidersHelper.InstantiateProviders(section.provider, _ipc, typeof(SqlImg));
_ip = _ipc[section.defaultProvider];
}
}
}
}
}
然后看看confi文件的配置
<configSections>
<section name="testmy" type="ps.ImageServiceSection,ps"
allowDefinition="MachineToApplication" restartOnExternalChanges="true"
/>
</configSections>
<appSettings/>
<connectionStrings>
<add name="ImageServiceConnectionString"
connectionString="server=PM_WANGCHAO_PC\SQLEXPRESS;database=test;uid=sa;pwd=123"
providerName="System.Data.SqlClient"/>
</connectionStrings>
<testmy defaultProvider="SqlImageProvider">
<myp>
<add name="SqlImageProvider" type="ps.SqlImg,ps" sqlconstr="ImageServiceConnectionString"/>
</myp>
</testmy>
代码贴完了，总的来说比较简单。相信大家对配置驱动又会加深理解老。
