博客园_MicroCoder

Proxy Pattern - C# 3.0 Design Patterns

2012-03-16T08:10:00Z

Proxy Pattern属于Structural Patterns

介绍：

Proxy Pattern的作用是为其他对象提供一个代理以控制对这个对象的访问，如何你的对象创建非常昂贵；需要访问控制；是一个远程对象或者调用之前需要采取一些其他操作，那么你可以考虑为该对象创建一个代理。

设计于实现：

ISubject：一个公共的接口供代理和被代理对象继承

Subject：需要被代理的对象

Proxy：代理对象 A class that creates, controls, enhances, and authenticates access to a Subject

public interface ISubject
{
string Request();
}

public class Subject : ISubject
{
#region ISubject Members
public string Request()
{
return "Subject Request ";
}
#endregion
}

public class Proxy : ISubject
{
Subject subject;
public string Request()
{
if (subject == null)
{
Console.WriteLine("Subject inactive");
subject = new Subject();
}
Console.WriteLine("Subject active");
return "Proxy: Call to " + subject.Request();
}
}
public class ProtectionProxy : ISubject
{
// An authentication proxy first asks for a password
Subject subject;
string password = "Abracadabra";

public string Authenticate(string supplied)
{
if (supplied != password)
{
return "Protection Proxy: No access";
}
subject = new Subject();
return "Protection Proxy: Authenticated";
}

public string Request()
{
if (subject == null)
{
return "Protection Proxy: Authenticate first";
}
return "Protection Proxy: Call to " + subject.Request();
}
}

[TestFixture]
public class ProxyPatternTest
{
[Test]
public void T1()
{
ISubject subject = new Proxy();
Console.WriteLine(subject.Request());

ISubject subject2 = new ProtectionProxy();

Console.WriteLine(subject2.Request());

Console.WriteLine((subject2 as ProtectionProxy).Authenticate("Abracadabra"));
Console.WriteLine(subject2.Request());

}
}

Decorator Pattern 和 Proxy Pattern 的区别：

Decorator Pattern 有"Smart Proxy" 可见两者有相同之处，在Decorator Pattern中装饰者和被装饰者都实现了相同的接口，这个Proxy Pattern一样代理和被代理的对象也同样实现了相同的接口。同时装饰者和代理都可以对实际的对象进行控制。

但是两者最显著的区别是Proxy Pattern是在代理类内部创建对象的实例，而Decorator Pattern是通过参数传递对象的实例。

var component = new Component();
//Component是通过构造函数的方式传递给DecoratorB的
var decoratorB = new DecoratorB(component);

public class Proxy : ISubject
{
       Subject subject;
       public string Request()
       {
           if (subject == null)
           {
               Console.WriteLine("Subject inactive");
              //在代理的内部创建类（Subject）的实例
               subject = new Subject();
           }

           …
       }
   }

参考文章：

1、The differences between Decorator Pattern and Proxy Pattern

2、How do the Proxy, Decorator, Adaptor, and Bridge Patterns differ?

本文链接

Decorator Pattern - C# 3.0 Design Patterns

2012-03-16T06:47:00Z

Decorator Pattern属于Structural Patterns

介绍：

Decorator pattern的作用是提供一种方式动态的给一个对象添加新的职责或状态，被装饰的对象并不知道被“装饰”了。A key implementation point in the Decorator pattern is that decorators both inherit the original class and contain an instantiation of it.

实现：

UML 类图

public interface IComponent
{
string Operation();
}
/// <summary>
/// 被装饰者
/// </summary>
public class Component : IComponent
{
#region IComponent Members
public string Operation()
{
return "I'm a photo;";
}
#endregion
}
/// <summary>
/// 装饰者A
/// </summary>
public class DecoratorA : IComponent
{
IComponent component;
public DecoratorA(IComponent component)
{
this.component = component;
}
#region IComponent Members
public string Operation()
{
return component.Operation() + "and decorated by DecoratorA";
}
#endregion
}
/// <summary>
/// 装饰者B
/// </summary>
public class DecoratorB : IComponent
{
IComponent component;
public string AddedState = " and added state";
public DecoratorB(IComponent component)
{
this.component = component;
}
#region IComponent Members
public string Operation()
{
return component.Operation() + "and decorated by DecoratorB";
}
public string AddedBehavior()
{
return " and added behavior by DecoratorB";
}
#endregion
}
public class Client
{
public static void Display(string s, IComponent component)
{
Console.WriteLine(s + component.Operation());
}
}
[TestFixture]
public class DecoratorTest
{
[Test]
public void T1()
{
var component = new Component();
Client.Display(string.Empty, component);
var decoratorB = new DecoratorB(component);
Client.Display("hello!", decoratorB);
}
}

本文链接

使用Mongodb的搜索拼音自动补全方案

2012-03-15T07:43:00Z

搜索的自动提示功能能给用户带来很好的搜索体验，由于中文的特点，如果搜索自动提示可以支持拼音的话会给用户带来更大的方便，免得切换输入法。目前大多数的电子商务网站都支持拼音提示功能。

关于多音字

由于中文存在多音字问题（读音，声调），例如调的读音有DIAO;TIAO 长的读音有CHANG;ZHANG 所以对于一个词语如果用程序组合可能有多个组合，比如美的空调有4中组合：meidikongtiao；meidikongdiao； meidekongtiao；meidekongdiao 如何处理这中问题要做到精确第一需要有拼音库还要分词，这种处理难度较大，第二种就是把所有可能组合在一起，这样的缺点是一个词汇组合太多（阶乘）；提示结果不准确。

大多数电子商务网站都采用第二种方案：例如洗衣机洗字有xian 和xi 两种读音。

淘宝商城：

卓越：

京东：

SQLServer还是MongoDB

如果使用sql server这样的关系型数据库需要见两张表一张数提示词一张表是对应的读音，这样不管存储还是读取都相对比较麻烦，同时这种查询数次较高（用户每输入一个字符都要查询数据库）对sql server 造成不必要的浪费。

MongoDB是一种非关系型的文档数据库，开源，免费，具有易于使用，效率高等特点，存储是JSON格式，强大的查询功能（数组和正则表达式的支持）。

比如美的空调可以存储为 {name:’美的空调’;pinyin:[meidikongtiao’,’meidekongtiao’]}

查选也很方便，例如我们用户输入xian，我们的查选语句就是这样的：

查询结果为：

关于汉字转拼音可参考：

使用Microsoft Visual Studio International Pack获得中文字符串的所有拼音组合（处理多音字）

本文链接

一个简单的ASP.NET WebForm "Model Binder"

2011-09-03T04:36:00Z

ASP.NET MVC 中有一个神器Model Binder，给开发带来很多便利，如果使用WebForm 开发的话，只能望洋兴叹了，不过人类是无法阻止程序猿解决问题的决心的。

废话不多说了，直接看看这个山寨版的 "Model Binder"

复杂类型使用示例

先定义几个简单的实体：

public class User
{
public int SysNo { get; set; }
public string Name { get; set; }
public bool Good { get; set; }
public DateTime Birthday { get; set; }
public Address Address { get; set; }
public int[] Test { get; set; }
public List<Order> Orders { get; set; }//不支持复杂列表类型的转换
}
public class Order
{
public string OrderID { get; set; }

}
public class Address
{
public User User { get; set; }
public int SysNo { get; set; }
public string Name { get; set; }
}

然后看看界面上表单的样子

看看效果

转换成功！！

如何判断用户没有输入或者转换失败呢？

很简单在Global中注册默认值

protected void Application_Start(object sender, EventArgs e)
{
RequestBinder.RegistDefaultValue<int>(-999999);
RequestBinder.RegistDefaultValue<DateTime>(DateTime.Parse("1900/01/01"));
}

上面是复杂类型，对于简单的更不在话下了，只要指定表单的Name就可以了

int sysno = RequestBinder.UpdateModel<int>("SysNO");

源码下载：

http://files.cnblogs.com/dushouke/RequestBinder.rar

本文链接

stackoverflow favorites

2011-09-03T02:10:00Z

2011-09-03T02:10:00Z2011-09-03T02:10:00ZMicroCoderhttp://www.cnblogs.com/dushouke/

本文链接

在ashx中使用aspx的OutputCached

2011-06-04T04:45:00Z

public class CacheHandler : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            OutputCachedPage page = new OutputCachedPage(new OutputCacheParameters
            {
                Duration = 60,
                Location = OutputCacheLocation.Server,
                VaryByParam = "v"
            });
            page.ProcessRequest(HttpContext.Current);
            context.Response.Write(DateTime.Now);
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
        private sealed class OutputCachedPage : Page
        {
            private OutputCacheParameters _cacheSettings;

            public OutputCachedPage(OutputCacheParameters cacheSettings)
            {
                // Tracing requires Page IDs to be unique.
                ID = Guid.NewGuid().ToString();
                _cacheSettings = cacheSettings;
            }

            protected override void FrameworkInitialize()
            {
                // when you put the <%@ OutputCache %> directive on a page, the generated code calls InitOutputCache() from here
                base.FrameworkInitialize();
                InitOutputCache(_cacheSettings);
            }
        }
    }

本文链接

Unix时间戳与C# DateTime时间类型互换

2011-01-26T14:20:00Z

/// <summary>
/// method for converting a UNIX timestamp to a regular
/// System.DateTime value (and also to the current local time)
/// </summary>
/// <param name="timestamp">value to be converted</param>
/// <returns>converted DateTime in string format</returns>
private static DateTime ConvertTimestamp(double timestamp)
{
//create a new DateTime value based on the Unix Epoch
DateTime converted = new DateTime(1970, 1, 1, 0, 0, 0, 0);

//add the timestamp to the value
DateTime newDateTime = converted.AddSeconds(timestamp);

//return the value in string format
return newDateTime.ToLocalTime();
}

/// <summary>
/// method for converting a System.DateTime value to a UNIX Timestamp
/// </summary>
/// <param name="value">date to convert</param>
/// <returns></returns>
private double ConvertToTimestamp(DateTime value)
{
//create Timespan by subtracting the value provided from
//the Unix Epoch
TimeSpan span = (value - new DateTime(1970, 1, 1, 0, 0, 0, 0).ToLocalTime());

//return the total seconds (which is a UNIX timestamp)
return (double)span.TotalSeconds;
}

本文链接

[转]SQL Server 事务处理回滚事务

2010-11-07T04:12:00Z

SET ANSI_NULLS ON

GO

SET QUOTED_IDENTIFIER ON

GO

CREATE TABLE [dbo].[t1]
(
     [Id] [INT] NOT NULL,
     [c1] [NVARCHAR](50) NULL,
     [c2] [DATETIME] NULL,
     CONSTRAINT [PK_Table1] PRIMARY KEY CLUSTERED ( [Id] ASC )WITH (PAD_INDEX =
     OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS =
     ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
)
ON [PRIMARY]

--解决方案一
DECLARE @iErrorCount INT

SET @iErrorCount = 0

BEGIN TRAN Tran_2008_10_07

INSERT INTO t1
            (Id,
             c1)
VALUES     (1,
            '1')

SET @iErrorCount=@iErrorCount + @@ERROR

INSERT INTO t1
            (Id,
             c1)
VALUES     (2,
            '2')

SET @iErrorCount=@iErrorCount + @@ERROR

INSERT INTO t1
            (Id,
             c1)
VALUES     ('xxxx3',
            '3')

SET @iErrorCount=@iErrorCount + @@ERROR

INSERT INTO t1
            (Id,
             c1)
VALUES     (4,
            '4')

SET @iErrorCount=@iErrorCount + @@ERROR

INSERT INTO t1
            (Id,
             c1)
VALUES     (5,
            '5')

SET @iErrorCount=@iErrorCount + @@ERROR

IF @iErrorCount = 0
BEGIN
      COMMIT TRAN Tran_2008_10_07
END
ELSE
BEGIN
      ROLLBACK TRAN Tran_2008_10_07
END

--解决方案二
BEGIN TRY
    BEGIN TRAN Tran_2008_10_07

    INSERT INTO t1
                (Id,
                 c1)
    VALUES     (1,
                '1')

    INSERT INTO t1
                (Id,
                 c1)
    VALUES     (2,
                '2')

    INSERT INTO t1
                (Id,
                 c1)
    VALUES     ('xxxx3',
                '3')

    INSERT INTO t1
                (Id,
                 c1)
    VALUES     (4,
                '4')

    INSERT INTO t1
                (Id,
                 c1)
    VALUES     (5,
                '5')

    COMMIT TRAN Tran_2008_10_07
END TRY

BEGIN CATCH
    RAISERROR 50005N'错误了'

    ROLLBACK TRAN Tran_2008_10_07
END CATCH

本文链接

代码片段——泛型类型转换

2010-10-19T10:05:00Z

public static class TConverter
{
public static T ChangeType<T>(object value)
{
return (T)ChangeType(typeof(T), value);
}
public static object ChangeType(Type t, object value)
{
TypeConverter tc = TypeDescriptor.GetConverter(t);
return tc.ConvertFrom(value);
}
public static void RegisterTypeConverter<T, TC>() where TC : TypeConverter
{
TypeDescriptor.AddAttributes(typeof(T), new TypeConverterAttribute(typeof(TC)));
}
}

本文链接

代码存档

2010-10-19T07:49:00Z

public static bool IsCached(HttpContext context, TimeSpan cacheDuration)
{
var modifiedSince = context.Request.Headers["If-Modified-Since"];
if (!string.IsNullOrEmpty(modifiedSince))
{
modifiedSince = Regex.Replace(modifiedSince, @";.*$", "");//ie6
}
DateTime modified;
if (DateTime.TryParse(modifiedSince, out modified) && modified.Add(cacheDuration) > DateTime.Now)
{
context.Response.StatusCode = 304;
context.Response.Status = "304 Not Modified";
return true;
}
return false;
}
public static void SetCachedHeader(HttpContext context, TimeSpan cacheDuration)
{
FieldInfo maxAge = context.Response.Cache.GetType().GetField("_maxAge",
BindingFlags.Instance | BindingFlags.NonPublic);
maxAge.SetValue(context.Response.Cache, cacheDuration);
//context.Response.Cache.SetMaxAge(cacheDuration);
context.Response.Cache.SetETag(string.Empty);
context.Response.Cache.SetCacheability(HttpCacheability.Public);
context.Response.Cache.SetLastModified(DateTime.Now);
context.Response.Cache.SetExpires(DateTime.Now.Add(cacheDuration));
context.Response.Cache.AppendCacheExtension(
"must-revalidate, proxy-revalidate");
}
public static void Cached(HttpContext context)
{
Cached(context, TimeSpan.FromMinutes(10));
}

public static void Cached(HttpContext context, TimeSpan cacheDuration)
{
if (!IsCached(context, cacheDuration))
{
SetCachedHeader(context, cacheDuration);
}
else
{
context.Response.End();
}

}
public static void GZIP(HttpContext context)
{
string acceptEncoding = context.Request.Headers["Accept-Encoding"];

if (!String.IsNullOrEmpty(acceptEncoding))
{
acceptEncoding = acceptEncoding.ToString().ToUpperInvariant();
//如果头部里有包含"GZIP”,"DEFLATE",表示你浏览器支持 GZIP,DEFLATE压缩
if (acceptEncoding.Contains("GZIP"))
{
//向输出流头部添加压缩信息
context.Response.AppendHeader("Content-encoding", "gzip");
context.Response.Filter = new GZipStream(context.Response.Filter, CompressionMode.Compress);
}
else if (acceptEncoding.Contains("DEFLATE"))
{
//向输出流头部添加压缩信息
context.Response.AppendHeader("Content-encoding", "deflate");
context.Response.Filter = new DeflateStream(context.Response.Filter, CompressionMode.Compress);
}
}
}

本文链接

博客园_MicroCoder

Proxy Pattern - C# 3.0 Design Patterns

Decorator Pattern - C# 3.0 Design Patterns

使用Mongodb的搜索拼音自动补全方案

一个简单的ASP.NET WebForm "Model Binder"

stackoverflow favorites

在ashx中使用aspx的OutputCached

Unix时间戳与C# DateTime时间类型互换

[转]SQL Server 事务处理 回滚事务

代码片段——泛型类型转换

代码存档

[转]SQL Server 事务处理回滚事务