大概看了下C#官方提供的IObservable接口以及IObserver接口來實現發佈和訂閱，寫的很標準，頗有表明性，作下筆記，之後要是項目須要用到發佈訂閱再基於本身的需求改：html
public class BaggageInfo
{
private int flightNo;
private string origin;
private int location;
internal BaggageInfo(int flight, string from, int carousel)
{
this.flightNo = flight;
this.origin = from;
this.location = carousel;
}
public int FlightNumber {
get { return this.flightNo; }
}
public string From {
get { return this.origin; }
}
public int Carousel {
get { return this.location; }
}
}
///
/// 發佈者
///
public class BaggageHandler : IObservable<BaggageInfo>
{
private List<IObserver<BaggageInfo>> observers;
private List<BaggageInfo> flights;
public BaggageHandler()
{
observers = new List<IObserver<BaggageInfo>>();
flights = new List<BaggageInfo>();
}
public IDisposable Subscribe(IObserver<BaggageInfo> observer)
{
// Check whether observer is already registered. If not, add it
if (! observers.Contains(observer)) {
observers.Add(observer);
// Provide observer with existing data.
foreach (var item in flights)
observer.OnNext(item);
}
return new Unsubscriber<BaggageInfo>(observers, observer);
}
// Called to indicate all baggage is now unloaded.
public void BaggageStatus(int flightNo)
{
BaggageStatus(flightNo, String.Empty, 0);
}
public void BaggageStatus(int flightNo, string from, int carousel)
{
var info = new BaggageInfo(flightNo, from, carousel);
// Carousel is assigned, so add new info object to list.
if (carousel > 0 && ! flights.Contains(info)) {
flights.Add(info);
foreach (var observer in observers)
observer.OnNext(info);
}
else if (carousel == 0) {
// Baggage claim for flight is done
var flightsToRemove = new List<BaggageInfo>();
foreach (var flight in flights) {
if (info.FlightNumber == flight.FlightNumber) {
flightsToRemove.Add(flight);
foreach (var observer in observers)
observer.OnNext(info);
}
}
foreach (var flightToRemove in flightsToRemove)
flights.Remove(flightToRemove);
flightsToRemove.Clear();
}
}
public void LastBaggageClaimed()
{
foreach (var observer in observers)
observer.OnCompleted();
observers.Clear();
}
}
internal class Unsubscriber<BaggageInfo> : IDisposable
{
private List<IObserver<BaggageInfo>> _observers;
private IObserver<BaggageInfo> _observer;
internal Unsubscriber(List<IObserver<BaggageInfo>> observers, IObserver<BaggageInfo> observer)
{
this._observers = observers;
this._observer = observer;
}
public void Dispose()
{
if (_observers.Contains(_observer))
_observers.Remove(_observer);
}
}
///
/// 訂閱者
///
public class ArrivalsMonitor : IObserver<BaggageInfo>
{
private string name;
private List<string> flightInfos = new List<string>();
private IDisposable cancellation;
private string fmt = "{0,-20} {1,5} {2, 3}";
public ArrivalsMonitor(string name)
{
if (String.IsNullOrEmpty(name))
throw new ArgumentNullException("The observer must be assigned a name.");
this.name = name;
}
public virtual void Subscribe(BaggageHandler provider)
{
cancellation = provider.Subscribe(this);
}
public virtual void Unsubscribe()
{
cancellation.Dispose();
flightInfos.Clear();
}
public virtual void OnCompleted()
{
flightInfos.Clear();
}
// No implementation needed: Method is not called by the BaggageHandler class.
public virtual void OnError(Exception e)
{
// No implementation.
}
// Update information.
public virtual void OnNext(BaggageInfo info)
{
bool updated = false;
// Flight has unloaded its baggage; remove from the monitor.
if (info.Carousel == 0) {
var flightsToRemove = new List<string>();
string flightNo = String.Format("{0,5}", info.FlightNumber);
foreach (var flightInfo in flightInfos) {
if (flightInfo.Substring(21, 5).Equals(flightNo)) {
flightsToRemove.Add(flightInfo);
updated = true;
}
}
foreach (var flightToRemove in flightsToRemove)
flightInfos.Remove(flightToRemove);
flightsToRemove.Clear();
}
else {
// Add flight if it does not exist in the collection.
string flightInfo = String.Format(fmt, info.From, info.FlightNumber, info.Carousel);
if (! flightInfos.Contains(flightInfo)) {
flightInfos.Add(flightInfo);
updated = true;
}
}
if (updated) {
flightInfos.Sort();
Console.WriteLine("Arrivals information from {0}", this.name);
foreach (var flightInfo in flightInfos)
Console.WriteLine(flightInfo);
Console.WriteLine();
}
}
}
using System;
using System.Collections.Generic;
public class Example
{
public static void Main()
{
//發佈者
BaggageHandler provider = new BaggageHandler();
// 訂閱者
ArrivalsMonitor observer1 = new ArrivalsMonitor("BaggageClaimMonitor1");
// 訂閱者
ArrivalsMonitor observer2 = new ArrivalsMonitor("SecurityExit");
// 發佈
provider.BaggageStatus(712, "Detroit", 3);
//訂閱
observer1.Subscribe(provider);
provider.BaggageStatus(712, "Kalamazoo", 3);
provider.BaggageStatus(400, "New York-Kennedy", 1);
provider.BaggageStatus(712, "Detroit", 3);
observer2.Subscribe(provider);
provider.BaggageStatus(511, "San Francisco", 2);
provider.BaggageStatus(712);
observer2.Unsubscribe();
provider.BaggageStatus(400);
provider.LastBaggageClaimed();
}
}
visual studio code .net 開發
Visual Studio確實是至關好用，各類簡化操做什麼的簡直不要太舒服。但其容量太大，有時不是很方便，因此今天簡單介紹一下另外一個工具--Visual Studio Code.linux
雖然相比於老大哥Visual Studio，VS Code有不少功能不完善，但它也更靈活輕便。而且VS Code還在不斷的更新當中，目前的最新版本是18年11月更新的1.30版本，包含了 多行搜索改進 等內容。git
下面以.Net開發爲例：github
不一樣於Visual Studio，在VS Code上進行.Net開發你須要安裝一些插件，點擊左側邊欄箭頭這個位置搜索web
安裝插件 C# (C# for Visual Studio Code (powered by OmniSharp)) (必須)算法
-
Lightweight development tools for .NET Core.
-
-
Great C# editing support, including Syntax Highlighting, IntelliSense, Go to Definition, Find
-
All References, etc.
-
Debugging support for .NET Core (CoreCLR). NOTE: Mono debugging is not supported. Desktop CLR debugging has limited support.
-
Support for project.json and csproj projects on Windows, macOS and Linux.
安裝插件 NuGet Package Manager (推薦，方便搜索，安裝Nuget包) (推薦)數據庫
-
Search the NuGet package repository for packages using either (partial or full) package name or another search term.
-
Add PackageReference dependencies to your .NET Core 1.1+ .csproj or .fsproj files from Visual Studio Code's Command Palette.
-
Remove installed packages from your project's .csproj or .fsproj files via Visual Studio Code's Command Palette.
-
Handles workspaces with multiple .csproj or .fsproj files as well as workspaces with single .csproj/.fsproj files.
-
-
-
For example:
-
-
-
Ctrl + P Then Shift + > Choose "Nuget Package Manager: Add Package". Then Input the keyword about the Nuget Package. Finally, Choose the project you want to add the Nuget package.
VSCode 安裝插件後通常須要從新激活以啓用插件。因爲VSCode自己不斷更新，對於某些版本的VSCode可能須要重啓應用，才能激活插件。
在VSCode中運行調試前，須要在.vscode路徑下額外配置兩個文件 launch.json 和 tasks.json， 來告訴vscode如何啓動項目。
Launch.json:編程
{
// Use IntelliSense to find out which attributes exist for C# debugging
// Use hover for the description of the existing attributes
// For further information visit https://github.com/OmniSharp/omnisharp-vscode/blob/master/debugger-launchjson.md
"version": "0.2.0",
"configurations": [
{
"name": ".NET Core Launch (web)",
"type": "coreclr",
"request": "launch",
"preLaunchTask": "build",
// If you have changed target frameworks, make sure to update the program path.
"program": "${workspaceRoot}/MyABP.Web/bin/Debug/netcoreapp2.1/MyABP.Web.dll",
"args": [],
"cwd": "${workspaceRoot}/MyABP.Web",
"stopAtEntry": false,
"internalConsoleOptions": "openOnSessionStart",
"launchBrowser": {
"enabled": true,
"args": "${auto-detect-url}",
"windows": {
"command": "cmd.exe",
"args": "/C start ${auto-detect-url}"
},
"osx": {
"command": "open"
},
"linux": {
"command": "xdg-open"
}
},
"env": {
"ASPNETCORE_ENVIRONMENT": "Development"
},
"sourceFileMap": {
"/Views": "${workspaceRoot}/Views"
}
},
{
"name": ".NET Core Attach",
"type": "coreclr",
"request": "attach",
"processId": "${command:pickProcess}"
}
]
}
若是你第一次運行某個項目，你須要確保全部引用的內容都存在，如上面的MyAbp.Web.dll文件.另外，這些配置不是固定不變的，你能夠根據你的須要來進行不一樣的配置。json
如上面c#
"preLaunchTask": "build" 指定了你的項目在launch以前要先進行build操做。
又如
"env": {
"ASPNETCORE_ENVIRONMENT": "Development"
}
指定了你要在「哪一個環境」下啓動你的項目。（實際上一個項目會有多種環境的配置，舉個例子 appsetings.Development.json 和 appseting.QA.json用於區分不一樣環境的配置，若是發如今QA環境出現了問題本地不能重現時，天然須要切換到目標環境來進行調試）
Tasks.json:
{
"version": "0.1.0",
"command": "dotnet",
"isShellCommand": true,
"args": [],
"tasks": [
{
"taskName": "build",
"args": [
"${workspaceRoot}/MyABP.Web/MyABP.Web.csproj"
],
"isBuildCommand": true,
"problemMatcher": "$msCompile"
}
]
}
這裏能夠配置一下Task，如上面的
"preLaunchTask": "build" 具體的任務流程即在這裏配置。
這裏除去筆者使用的Web項目的配置外，固然還能夠有多種其餘項目應用的配置，如
這些配置完成以後，點擊如圖所示這個位置進入調試面板，而後點擊上面的綠色三角就能夠開始你的調試啦
/ **************************************************分割線*************************************************************/
vscode下經常使用DotNet命令
dotnet所使用的命令均可以使用 --help的方式來查看更詳細的用法。
如dotnet --help
在項目開發過程當中，經常使用的命令有
dotnet new
用於新建內容，dotnet提供了許多模板,如Console Application， Class Library等等。
使用dotnet new時須要注意新建的項目是基於.Net Framework仍是基於.NetCore.
可使用 -f 來指定.
dotnet restore
主要是尋找當前目錄下的項目文件（project.json），而後利用NuGet庫還原整個項目的依賴庫，而後遍歷每一個目錄，生成項目文件，繼續還原該項目文件中的依賴項 --CSDN yangzhenping
如下命令不解釋了，可使用 --help 查看具體用法
dotnet build
dotnet run
dotnet publish
設計模式之☞策略模式
策略模式：它定義了算法家族，分別封裝起來，讓它們之間能夠相互替換，此模式讓算法的變化，不會影響到使用算法的客戶。
今天來經過一個案例，來說一下商場的促銷案例。通常商場會有那些活動呢？總結了下，通常會有這3種促銷活動：一、正常收費；二、打折；三、滿多少返多少
面向對象的編程，並非類越多越好，類的劃分是爲了封裝，但分類的基礎是抽象，具備相同屬性和功能的抽象集合纔是類。
現金收費抽象類：
1 abstract class CashSupper //現金收費抽象類
2 {
3 public abstract double acceptCash(double money);//現金收取類的抽象方法，收取現金，參數爲原價，返回爲當前價
4 }
正常收費子類：
1 class CashNormal : CashSupper //正常收費子類
2 {
3 public override double acceptCash(double money)
4 {
5 return money;
6 }
7 }
打折收費子類：
1 class CashRebate : CashSupper //打折收費子類
2 {
3 private double moneryRebate = 1d;
4 public CashRebate(string moneryRebate)
5 {
6 this.moneryRebate = double.Parse(moneryRebate); //打折收費，初始化時，必需要輸入折扣率，如八折，就是0.8
7 }
8 public override double acceptCash(double money)
9 {
10 return money * moneryRebate;
11 }
12 }
返利收費子類：
1 class CashReturn : CashSupper
2 {
3 private double moneryCondition = 0.0d;
4 private double MoneryReturn = 0.0d;
5 public CashReturn(string moneryCondition,string moneryReturn) //返利收費，初始化時必需要輸入返利條件和返利值，好比滿300返100，則moneryCondition=300，moneryReturn=100
6 {
7 this.moneryCondition =double.Parse(moneryCondition);
8 this.MoneryReturn = double.Parse(moneryReturn);
9 }
10 public override double acceptCash(double money)
11 {
12 double result = money;
13 if (money>=moneryCondition) //若大於返利條件，則須要減去返利值
14 {
15 result = money - Math.Floor(money / moneryCondition) * MoneryReturn;
16 }
17 return result;
18 }
19 }
現金收費工廠類：
1 class CashFactory
2 {
3 public static CashSupper createCashAccept(string type)
4 {
5 CashSupper cs = null;
6 switch (type)
7 {
8 case "正常收費":
9 cs = new CashNormal();
10 break;
11 case "滿300反100":
12 CashReturn cr1 = new CashReturn("300","100");
13 cs = cr1;
14 break;
15 case "打8折":
16 CashRebate cr2 = new CashRebate("0.8");
17 cs = cr2;
18 break;
19 }
20 return cs;
21 }
22 }
CashContext類：
1 class CashContext
2 {
3 private CashSupper cs=null; //聲明一個CashSuper
4 public CashContext(string type) //表示收費的類型
5 {
6 switch (type)
7 {
8 case "正常收費":
9 CashNormal cs0 = new CashNormal();
10 cs = cs0;
11 break;
12 case "滿300返100":
13 CashReturn cr1 = new CashReturn("300","100");
14 cs = cr1;
15 break;
16 case "打8折":
17 CashRebate cr2 = new CashRebate("0.8"); //將實例化具體策略的過程由客戶端轉移到Context類中。簡單工廠的引用
18 cs = cr2;
19 break;
20 }
21 }
22 public double GetResult(double Money)
23 {
24 return cs.acceptCash(Money); //根據收費策略的不一樣，得到計算結果
25 }
26 }
界面：
調用：
1 double total = 0.0d; //用戶總計
2 private void btnOk_Click(object sender, EventArgs e)
3 {
4 CashContext cc = new CashContext(cmbType.SelectedItem.ToString());
5 double totalPrices = 0d;
6 totalPrices = cc.GetResult(Convert.ToDouble(txtPrice.Text)*Convert.ToDouble(txtNumber.Text)); //經過對Context的GetResult方法的調用，能夠獲得收取費用的結果，讓具體算法與客戶進行隔離
7 total = total + totalPrices;
8 listBox1.Items.Add("單價:"+txtPrice.Text+"數量:"+txtNumber.Text+" "+cmbType.SelectedItem+"合計:"+totalPrices.ToString());
9 label5.Text = total.ToString();
10 }
C#字符串轉二進制、二進制轉字符串
最近公司要作一個操做日誌的模塊，若是將操做日誌以字符串的形式存到後臺數據庫，很是浪費內存，不可取，特地寫了字符串與二進制相互轉換的函數。
一、字符串轉二進制
1 private string StringToBinary(string str)
2 {
3 byte[] data = Encoding.Unicode.GetBytes(str);
4 StringBuilder sb = new StringBuilder(data.Length*8);
5 foreach (byte item in data)
6 {
7 sb.Append(Convert.ToString(item,2).PadLeft(8,'0'));
8 }
9 return sb.ToString();
10 }
二、二進制轉字符串
1 private string BinaryToString(string str)
2 {
3 System.Text.RegularExpressions.CaptureCollection cs = System.Text.RegularExpressions.Regex.Match(str,@"([01]{8})+").Groups[1].Captures;
4 byte[] data = new byte[cs.Count];
5 for (int i = 0; i < cs.Count; i++)
6 {
7 data[i] = Convert.ToByte(cs[i].Value,2);
8 }
9 return Encoding.Unicode.GetString(data,0,data.Length);
10 }
下面隨便寫了一條Sql語句，便於測試二者是否轉換成功？
轉碼成功！
c# 接口的協變和逆變
若是派生類只是用於輸出值，那麼這種結構化的委託有效性之間的常數關係叫作協變
就是建立一個派生類委託對象 讓派生類賦值給基類對象 協變關鍵字out
對指望傳入基類時容許傳入派生對象的特性叫逆變 逆變關鍵字in
看一下實現代碼
class Animal { public string Name; }
class Dog:Animal { }
interface Im<out T>//協變
{
T GetT();
}
class MyClass<T> : Im<T>
{
public T[] item = new T[2];
public T GetT()
{
return item[0];
}
}
class Program
{
static void DoSomething(Im<Animal> im)
{
Console.WriteLine(im.GetT().Name);
}
static void Main(string[] args)
{
MyClass<Dog> myClass = new MyClass<Dog>();
myClass.item[0] = new Dog() { Name = "AVT" };
Im<Animal> ANIMAL = myClass;
DoSomething(myClass);
}
}
c# 使用迭代器來建立可枚舉類型
class Program
{
public IEnumerator<string> GetEnumerator()
{
IEnumerable<string> my = BlackAndWhite();
return my.GetEnumerator();
}
public IEnumerable<string> BlackAndWhite()
{
yield return "black";
yield return "gray";
yield return "white";
}
static void Main(string[] args)
{
Program program = new Program();
foreach (var item in program)
{
Console.WriteLine(item);
}
foreach (var item in program.BlackAndWhite())
{
Console.WriteLine(item);
}
}
}
c# 建立，加載，修改XML文檔
using System.Xml.Linq;
static void Main(string[] args) { XDocument xDocument = new XDocument(new XElement("mployess", //建立跟元素 new XElement("name", "a"),new XElement("name","b")));//建立元素 xDocument.Save("地址"); XDocument empole = XDocument.Load("地址");//加載xml 文檔 能夠保證修改 Console.WriteLine(empole); }