C#知识点-16（计算器插件开发、事件、递归、XML）

计算器插件开发

1、Calculator.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Calculator_DLL
{//用来明确所有插件开发人员的开发规范public abstract class Calculator{public int NumberOne { get;set; }public int NumberTwo { get;set; }public abstract string Oper { get; }//抽象属性public Calculator(int n1,int n2){this.NumberOne = n1;this.NumberTwo = n2;}//提供一个计算的方法，具体的计算公式，留给插件开发人员public abstract int GetResult();}
}

2、Calculator_Add.cs

using Calculator_DLL;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Calculator_DLL_Add
{public class Calculator_Add : Calculator{public Calculator_Add(int n1, int n2) : base(n1, n2){}public override string Oper { get { return "+"; } }public override int GetResult(){return this.NumberOne + this.NumberTwo;}}
}

3、Calculator_Sub.cs

using Calculator_DLL;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;namespace Calculator_DLL_Sub
{public class Calculator_Sub : Calculator{public Calculator_Sub(int n1, int n2) : base(n1, n2){}public override string Oper { get { return "-"; } }public override int GetResult(){return this.NumberOne-this.NumberTwo;}}
}

4、Calculator_Factory.cs

using Calculator_DLL;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;namespace Calculator_Factory_DLL
{/// <summary>/// 计算器插件的工厂，根据用户的选择，返回对应的计算对象（插件对象）/// </summary>public class Calculator_Factory{/// <summary>/// 根据用户选择的操作符，创建对应的插件对象（是用父类屏蔽了所有子类插件对象）/// </summary>/// <param name="oper">用户选择的操作符</param>/// <param name="n1">数字1</param>/// <param name="n2">数字2</param>/// <returns>对应的计算插件对象</returns>public static Calculator GetCalculator(string oper,int n1,int n2){Calculator cal = null;//Assembly:表示程序集 GetExecutingAssembly():获取包含当前执行的代码的程序集  Location:位置，也就是路径string path = Assembly.GetExecutingAssembly().Location;//GetDirectoryName():返回指定路径字符串的目录信息path = Path.GetDirectoryName(path);//DLL程序集的上一个目录，也就是Debug目录path = Path.Combine(path, "Plug-in-Components");//读取文件夹下的所有插件(Add、Sub)string[] files = Directory.GetFiles(path);//遍历所有类库文件，从里面找到我们规范的类型（类型要求：继承了Calculator，并且重写了其中的抽象成员，并且不是抽象的）foreach (var file in files){//LoadFile():加载指定路径上的程序集文件的内容Assembly ass = Assembly.LoadFile(file);//GetExportedTypes():获取程序集中定义的公共类型Type[] types = ass.GetExportedTypes();//判断类型是否为我们需要的类型foreach (var type in types){//开始筛选//IsAssignableFrom():确定指定类型的实例是否能分配给当前实例（看有没有继承关系）//IsAbstract:判断当前类型是否是抽象的if (typeof(Calculator).IsAssignableFrom(type)&&!type.IsAbstract){//创建type的对象object o =Activator.CreateInstance(type,n1,n2);cal = o as Calculator;//如果计算对象的Oper属性==用户传入的Oper值if (cal.Oper==oper){return cal;}}}}return cal;}}
}

5、Form1.cs

using Calculator_DLL;
using Calculator_Factory_DLL;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;namespace 插件记事本
{public partial class Form1 : Form{public Form1(){InitializeComponent();}private void Form1_Load(object sender, EventArgs e){//1、读取配置文件，创建对应的按钮对象string path = Assembly.GetExecutingAssembly().Location;path=Path.GetDirectoryName(path);path = Path.Combine(path, "CalculatorConfig.txt");//2、读取配置文件string[] operLines = File.ReadAllLines(path);int x = 100;//3、创建按钮对象for (int i = 0; i < operLines.Length; i++){Button btn = new Button();btn.Text = operLines[i];btn.Size = new Size(75, 23);btn.Location = new Point(326 + i * x, 257);btn.Click += Btn_Click;this.Controls.Add(btn);}}private void Btn_Click(object sender, EventArgs e){Button btn = sender as Button;string oper = btn.Text;Calculator cal = Calculator_Factory.GetCalculator(oper,int.Parse(txtNumberOne.Text),int.Parse(txtNumberTwo.Text));if (cal != null){lblResult.Text = cal.GetResult().ToString();}}}
}

事件

概念：事件，就是一个类型安全的委托（事件是安全的，因为在类的外部，事件只能被赋值，而不能被调用）
事件的三个重要组成部分：注册事件、触发事件、响应事件

递归

概念：在方法中，自己调用自己。必须在满足某个条件的时候，退出递归

递归查找所有的文件夹和文件

        private void Form1_Load(object sender, EventArgs e){//递归加载指定目录下，所有的文件夹和文件string path = @"C:\Windows\Microsoft.NET\Framework64\v4.0.30319";LoadData(path, treeView2.Nodes);}private void LoadData(string path, TreeNodeCollection nodes){//1、获取该路径下所有的文件夹string[] dirs = Directory.GetDirectories(path);//1.1 把所有的子目录的路径，添加到Treeview上foreach (var item in dirs){//tn就是根节点TreeNode tn = nodes.Add(Path.GetFileName(item));LoadData(item, tn.Nodes);}//2、获取该路径下所有的文件string[] files = Directory.GetFiles(path);foreach (var item in files){nodes.Add(Path.GetFileName(item));}}

XML

XML：可扩展的标记语言

通过代码创建XML文档

    internal class Program{static void Main(string[] args){//1、在内存中，创建XML文档对象XmlDocument xml = new XmlDocument();//2、创建文档声明XmlDeclaration dec = xml.CreateXmlDeclaration("1.0", "utf-8", null);//2.1 把创建的文档声明，添加到xml文档中xml.AppendChild(dec);//3、创建根节点XmlElement books = xml.CreateElement("Books");//3.1 把创建的根节点，添加到xml文档中xml.AppendChild(books);//4.1、给根节点，添加对应的属性XmlElement book1 = xml.CreateElement("Book");//Attribute :特性  [Serilizeble]  Property：属性XmlAttribute book1_id = xml.CreateAttribute("ID");//给属性赋值book1_id.Value = "00001";//把属性跟Book标签绑定到一起book1.Attributes.Append(book1_id);books.AppendChild(book1);//4.2 给根节点，添加对应的子节点XmlElement book1_name = xml.CreateElement("Name");//给子节点赋值book1_name.InnerText = "金瓶梅";book1.AppendChild(book1_name);//4.2 给根节点，添加对应的子节点XmlElement book1_author = xml.CreateElement("Author");//给子节点赋值book1_author.InnerText = "西门大官人";book1.AppendChild(book1_author);//4.2 给根节点，添加对应的子节点XmlElement book1_price = xml.CreateElement("Price");//给子节点赋值book1_price.InnerText = "10";book1.AppendChild(book1_price);//4.1、给根节点，添加对应的属性XmlElement book2 = xml.CreateElement("Book");//Attribute :特性  [Serilizeble]  Property：属性XmlAttribute book2_id = xml.CreateAttribute("ID");//给属性赋值book2_id.Value = "00002";//把属性跟Book标签绑定到一起book2.Attributes.Append(book2_id);books.AppendChild(book2);//4.2 给根节点，添加对应的子节点XmlElement book2_name = xml.CreateElement("Name");//给子节点赋值book2_name.InnerText = "水浒传";book2.AppendChild(book2_name);//4.2 给根节点，添加对应的子节点XmlElement book2_author = xml.CreateElement("Author");//给子节点赋值book2_author.InnerText = "潘金莲";book2.AppendChild(book2_author);//4.2 给根节点，添加对应的子节点XmlElement book2_price = xml.CreateElement("Price");//给子节点赋值book2_price.InnerText = "20";book2.AppendChild(book2_price);xml.Save("Books.xml");Console.WriteLine("保存OK");Console.ReadKey();}}

对XML增删改查

    internal class Program{static void Main(string[] args){List<Person> listPerson = new List<Person>();listPerson.AddRange(new Person[] {new Person() {Name= "张三",Age=19,Gender='男' },new Person() {Name= "李四",Age=20,Gender='女' },new Person() {Name= "王五",Age=21,Gender='中' }});//把集合中的数据，写入到xml文档中//1、创建文档对象XmlDocument doc = new XmlDocument();//2、创建文档声明XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", "utf-8", null);doc.AppendChild(dec);//3、创建根节点XmlElement xmlPersons = doc.CreateElement("Persons");doc.AppendChild(xmlPersons);int i = 0;//4、遍历泛型集合，把集合中的Person对象，以元素的形式，添加到XML文档中foreach (var item in listPerson){i++;//4.1 每一个Person对象，都是一个节点XmlElement person = doc.CreateElement("Person");XmlAttribute att = doc.CreateAttribute("ID");att.Value = i.ToString();person.Attributes.Append(att);//4.2 把创建的子节点，添加到根节点上xmlPersons.AppendChild(person);//4.3 给子节点，添加对应的Name、Age、GenderXmlElement name = doc.CreateElement("Name");name.InnerText = item.Name;//4.4 把子节点Name，添加到根节点Person上person.AppendChild(name);//4.3 给子节点，添加对应的Name、Age、GenderXmlElement age = doc.CreateElement("Age");age.InnerText = item.Age.ToString();//4.4 把子节点Name，添加到根节点Person上person.AppendChild(age);//4.3 给子节点，添加对应的Name、Age、GenderXmlElement gender = doc.CreateElement("Gender");gender.InnerText = item.Gender.ToString();//4.4 把子节点Name，添加到根节点Person上person.AppendChild(gender);}doc.Save("Person.xml");Console.WriteLine("保存成功");Console.ReadKey();}}class Person{public string Name { get; set; }public int Age { get; set; }public char Gender { get; set; }}