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DoubanFm之设计模式(一)

柳俊健
2023-12-01

  前两版DoubanFm写的太戳,第一版可以忽略,当是熟悉WP手机的一些API。。

第二版用了比较多的依赖注入,熟悉了Messenger,过后越写越大,感觉不对,赶快打住。。现在开始好好思考各模块了。

在Http请求方面,在知道了Restful后还没有机会使用它,感觉Restful应该还不错,不过我还是为我的Http请求使用了下面的设计模式

一.工厂方法

1.抽象产品

UML有空再画,先上代码,

使用Rx建立抽象的Get类产品,如下:

 1 public  abstract class HttpGetMethodBase<T>
 2     {
 3             public virtual IObservable<T> Get(string Url)//设置虚拟方法是为了多态 但是这里不用设置应该也可以
 4             {
 5                 //多态既是为了用子类的方法
 6                 //其实我这里不需要用子类的方法
 7                 //写了应该也可以
 8                 //只要注意子类的Override
 9                 var func = Observable.FromAsyncPattern<HttpWebRequest, T>(Webrequest, WebResponse);
10                 HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(Url);
11                 return func(request);
12             }
13            private  IAsyncResult Webrequest(HttpWebRequest request, AsyncCallback callbcak, object ob)
14             {
15                 return request.BeginGetResponse(callbcak, request);
16             }
17 
18            //发的请求用的是父类的get,WebResponse用的是子类的
19             protected    abstract T WebResponse(IAsyncResult result);
20      }

作为抽象的产品,有些方法可以共享,比如Get方法。要重写的是WebResponse

2.具体产品

(1)返回stream的产品

 1   public class HttpGetStream : HttpGetMethodBase<Stream>
 2     {
 3         protected override Stream WebResponse(IAsyncResult result)
 4         {
 5             try
 6             {
 7                 var request = result.AsyncState as HttpWebRequest;
 8                 HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result);
 9                 #region ignore
10                 if (response.Cookies != null)
11                 {
12                     foreach (Cookie cookie in response.Cookies)
13                     {
14                         Debug.WriteLine(cookie.Value);
15                     }
16                 }
17                 Debug.WriteLine(response.ContentType);
18                 Debug.WriteLine(response.StatusDescription);
19                 if (response.Headers["Set-Cookie"] != null)
20                 {
21                     //setting may write
22                     Debug.WriteLine(response.Headers["Set-Cookie"]);
23                 }
24                 #endregion
25                return  response.GetResponseStream();
26             }
27             catch
28             {
29                 Debug.WriteLine("WEBERROR");
30                 return null;
31             }
32         }
33     }

(2)返回string的产品

 1   public class HttpGetString : HttpGetMethodBase<string>
 2     {
 3         protected  override string WebResponse(IAsyncResult result)
 4         {
 5             try
 6             {
 7                 var request = result.AsyncState as HttpWebRequest;
 8                 HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result);
 9                 #region ignore
10                 if (response.Cookies != null)
11                 {
12                     foreach (Cookie cookie in response.Cookies)
13                     {
14                         Debug.WriteLine(cookie.Value);
15                     }
16                 }
17                 Debug.WriteLine(response.ContentType);
18                 Debug.WriteLine(response.StatusDescription);
19                 if (response.Headers["Set-Cookie"] != null)
20                 {
21                     //setting may write
22                     Debug.WriteLine(response.Headers["Set-Cookie"]);
23                 }
24                 #endregion
25                 Stream stream = response.GetResponseStream();
26                 using (StreamReader sr = new StreamReader(stream))
27                 {
28                     return sr.ReadToEnd(); 
29                 }
30             }
31             catch 
32             {
33                 Debug.WriteLine("WEBERROR");
34                 return null;
35             }
36         }
37     }

(3)返回位图的产品

 1   public class HttpGetBitmapImage : HttpGetMethodBase<BitmapImage>
 2     { 
 3         protected override BitmapImage  WebResponse(IAsyncResult result)
 4         {
 5             try
 6             {
 7                 var request = result.AsyncState as HttpWebRequest;
 8                 HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result);
 9                 #region ignore
10                 if (response.Cookies != null)
11                 {
12                     foreach (Cookie cookie in response.Cookies)
13                     {
14                         Debug.WriteLine(cookie.Value);
15                     }
16                 }
17                 Debug.WriteLine(response.ContentType);
18                 Debug.WriteLine(response.StatusDescription);
19                 if (response.Headers["Set-Cookie"] != null)
20                 {
21                     //setting may write
22                     Debug.WriteLine(response.Headers["Set-Cookie"]);
23                 }
24                 #endregion
25                 Stream stream = response.GetResponseStream();
26                 BitmapImage bitmapimage = new BitmapImage();
27                 bitmapimage.SetSource(stream);
28                 return bitmapimage;
29             }
30             catch
31             {
32                 Debug.WriteLine("WEBERROR");
33                 return null;
34             }
35         }
36     }

现在主要有三种产品,如果以后有返回音频的产品,就照搬就好了,这样便于扩展。

3.接口工厂(不叫抽象工厂是怕跟抽象工厂模式冲突)

(1)用于创建对象(产品)的接口

interface IHttpGet<T>
    {
        HttpGetMethodBase<T> CreateHttpRequest();
    }

(2)具体的工厂

具体工厂都用来创建具体的产品

1.string(get)工厂

1  public class StringHttpFactory:IHttpGet<string>
2     {
3          public HttpGetMethodBase<string>  CreateHttpRequest()
4         {
5             return new HttpGetString();
6         }
7     }

2.stream(get)工厂

1   public class StreamHttpFactory : IHttpGet<Stream>
2     {
3 
4         public HttpGetMethodBase<Stream> CreateHttpRequest()
5         {
6             return new HttpGetStream();
7         }
8     }

3.位图工厂

1 public class BitmapImageHttpFactory : IHttpGet<BitmapImage>
2     {
3         public HttpGetMethodBase<BitmapImage> CreateHttpRequest()
4         {
5             return new HttpGetBitmapImage();
6         }
7     }

 

客户端调用:

客户端调用还是得知道具体的工厂型号,所以这里我打个问号,先看看代码吧

1   IHttpGet<string> factory = new StringHttpFactory();//string 工厂
2             factory.CreateHttpRequest().Get("http://douban.fm/j/mine/playlist?from=mainsite&channel=0&kbps=128&type=n").Subscribe(
3                 (result) =>
4                 {
5                   7                 });

代码new了一个具体的工厂,这里并没有达到真正的解耦,所以我考虑看能不能以后做

1。配置文件反射处理

2.依赖注入。

//to be continued................

 

 二.职责链

先看看背景。

虽然用Newtonsoft的json库很爽,但是面对复杂的json串,不能很好的面对它的变化,变化点在于,JToken[][][][][][][][][],中括号的个数未知,我不知道哪天出来的json串会有几个[],如果使用到解析json串的地方很多,这个中括号的数量会非常多,看着非常恶心。。。。。。。。当然也许Newtonsoft有解决办法,但是我没摸索出来。

1.Json串的多样性

json串是由Web服务端安排的,各种命名,各种key/vaule,客户端很难应对这种变。  

用职责链的效果是:客户端只用发出获得的json字符串,就可以获得与之对应的类,至于json串怎么被处理的,客户端不知道

上代码

 1   public abstract class RequestorBase<T>
 2     {
 3         protected RequestorBase<T> Successor;
 4         internal void SetSucessor(RequestorBase<T> suc)
 5         {
 6             Successor = suc;
 7         }
 8         public abstract T ProcessRequest(string json);//抽象不依赖于具体,抽象依赖于抽象
 9     }

10 public class Requestor1<T> : RequestorBase<T> 11 { 12 public override T ProcessRequest(string json) 13 { 14 try 15 { 16 return JsonConvert.DeserializeObject<T>(JToken.Parse(json)["song"].ToString()); 17 } 18 catch 19 { 20 Debug.WriteLine("这个是在职责链中的该有的异常"); 21 return Successor.ProcessRequest(json); 22 } 23 } 24 } 25 public class Requestor2<T> : RequestorBase<T> 26 { 27 public override T ProcessRequest(string json) 28 { 29 try 30 { 31 return JsonConvert.DeserializeObject<T>(JToken.Parse(json)["song"][0].ToString()); 32 } 33 catch 34 { 35 Debug.WriteLine("这个是在职责链中的该有的异常"); 36 return Successor.ProcessRequest(json); 37 } 38 } 39 } 40 public class Requestor3<T> : RequestorBase<T> 41 { 42 public override T ProcessRequest(string json) 43 { 44 Debug.WriteLine("在职责链中没有能找到处理请求的方法,返回Default"); 45 return default(T); 46 //NO Chain 继续下去了 47 } 48 }

不同的职责人作不同的json串解析。

 

然后再使用

三.单例模式

使用单例模式来创建管理职责链,使用单例管理职责链的目的是职责链只负责处理json串,他们都是无状态的,所有把他们的方法装入内存就可以了。

 1   public class ManagerResponsibilityChain<T>
 2     {
 3        static private RequestorBase<T> _startrequestor;
 4        static public RequestorBase<T> Instance_Startrequestor
 5         {
 6             get 
 7             {
 8                 if (_startrequestor == null)
 9                 {
10                     Inital();
11                 }
12                 return _startrequestor; 
13             }
14         }
15         private ManagerResponsibilityChain()
16         {
17            
18         }
19         static private void Inital()
20         {
21             _startrequestor = new Requestor1<T>();
22             var secondrequestor = new Requestor2<T>();
23             var thridrequestor = new Requestor3<T>();
24             _startrequestor.SetSucessor(secondrequestor);
25             secondrequestor.SetSucessor(thridrequestor);//requestor3 is the end 
26         }
27     }

今天就到这。

后面再来追加一下:

对于上面的职责链,要想增加职责者,难免会忘记增加的过程,要插入在倒数第二个地方,再重新设置后两个的职责链

 

 1    public class ManagerResponsibilityChain<T>
 2     {
 3         static private RequestorBase<T> _startrequestor;
 4         static public RequestorBase<T> Instance_Startrequestor
 5         {
 6             get
 7             {
 8                 if (_startrequestor == null)
 9                 {
10                     Inital();
11                 }
12                 return _startrequestor;
13             }
14         }
15         private ManagerResponsibilityChain()
16         {
17 
18         }
19         static public List<RequestorBase<T>> RequestList=new List<RequestorBase<T>>();
20         static private void InsertARequestor(RequestorBase<T> InsertItem)
21         {
22             RequestList.Insert(RequestList.Count - 1, InsertItem);
23             InsertItem.SetSucessor(RequestList[RequestList.Count - 1]);
24             RequestList[RequestList.Count - 3].SetSucessor(InsertItem);
25 
26         }
27      
28 
29         static private void Inital()
30         {
31            
32             _startrequestor = new Requestor1<T>();
33             var secondrequestor = new Requestor2<T>();
34             var thridrequestor = new Requestor3<T>();
35             RequestList.Add(_startrequestor);
36             RequestList.Add(secondrequestor);
37             RequestList.Add(thridrequestor);
38             _startrequestor.SetSucessor(secondrequestor);
39             secondrequestor.SetSucessor(thridrequestor);//requestor3 is the end 
40 
41 
42             InsertARequestor(new Requestor4<T>());
43             InsertARequestor(new Requestor5<T>());
44             InsertARequestor(new Requestor6<T>());
45         }
46      
47     }

 或者是

 1   public class ManagerResponsibilityChain<T>
 2     {
 3         static private RequestorBase<T> _startrequestor;
 4         static public RequestorBase<T> Instance_Startrequestor
 5         {
 6             get
 7             {
 8                 if (_startrequestor == null)
 9                 {
10                     Inital();
11                 }
12                 return _startrequestor;
13             }
14         }
15         private ManagerResponsibilityChain()
16         {
17 
18         }
19 
20       static  private void InsertARequestor(RequestorBase<T> InsertItem, List<RequestorBase<T>> RequestList)
21         {
22             RequestList.Insert(RequestList.Count - 1, InsertItem);
23             InsertItem.SetSucessor(RequestList[RequestList.Count - 1]);
24             RequestList[RequestList.Count - 3].SetSucessor(InsertItem);
25 
26         }
27      
28 
29         static private void Inital()
30         {
31             List<RequestorBase<T>> RequestList = new List<RequestorBase<T>>();
32             _startrequestor = new Requestor1<T>();
33             var secondrequestor = new Requestor2<T>();
34             var thridrequestor = new Requestor3<T>();
35             RequestList.Add(_startrequestor);
36             RequestList.Add(secondrequestor);
37             RequestList.Add(thridrequestor);
38             _startrequestor.SetSucessor(secondrequestor);
39             secondrequestor.SetSucessor(thridrequestor);//requestor3 is the end 
40 
41 
42             InsertARequestor(new Requestor4<T>(), RequestList);
43             InsertARequestor(new Requestor5<T>(), RequestList);
44             InsertARequestor(new Requestor6<T>(), RequestList);
45         }
46      
47     }

 

转载于:https://www.cnblogs.com/07lyt/p/3991614.html

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