关于c#高级语法
第一章：c#委托
创建委托
//创建一个委托 delegate
public delegate void zj(string s);
创建委托类型对象把方法当作参数传进来
- 委托的类型和参数必须和委托的方法的类型和参数一样的
static void Main(string[] args)
{
// 创建委托类型的对象 ，将方法名作为参数传递进来
zj zj = new zj(Mf);
zj.Invoke("张三");
zj zj1 = maif;//简化方式
zj1.Invoke("小沈");
//多播委托
zj += maif;
//删除委托 : zj-=maif;
zj("张三");
}
public static void maif(string s)
{
Console.WriteLine(s+"卖出一套房子");
}
public static void Mf(string s)
{
Console.WriteLine(s+"买了一套汤臣一品");
}
-
可以创建一个以委托为参数的方法
public delegate void Act(); public static void action(Act act) { act.Invoke(); }
匿名类型
var a=new {
id=511,
Name="帅气",
age=5
}
a.GetType();//获取类型
-
委托匿名
//声明一个委托类 public delegate void other(int a, int b); other other = delegate (int x, int y) { Console.WriteLine("{2}+{1}={0}", x + y , x, y); }; other.Invoke(6, 7);
c#扩展方法
自定义内方法
public static class StringExd
{
public static int count(this string s)
{
return s.Split(new char[] { ' ','.',',','?'},StringSplitOptions.RemoveEmptyEntries).Count();
}
}
//运用
string s="hellow, how are you";
int cout=count(s);//解决的方法
console.writeLine(count)//有多少个单词
枚举类
//1-100被3整除的数 ，yield关键字
// 不断返回
public static IEnumerable<int> getlist()
{
for (int i = 1; i <= 100; i++)
{
if (i % 3 == 0)
{
yield return i;
}
}
}
lambda
public delegate void weiT(int a, int b);
weiT weiT = new weiT((int x,int y)=> {
Console.WriteLine("{0}+{1}={2}",x,y,x+y);
});
//两种采用
new weiT((x, y)=> {
Console.WriteLine("{0}+{1}={2}",x,y,x+y);
})(8,9)；
//Action内置的委托方法《string》定义类型
new Action<string>((s) =>
{
Console.WriteLine(s + "你吃了吗");
})("小张");
匿名方法
public delegate int weiT(int a, int b);
weiT wei=delegate (int x,int y){
return x+y;
}
wei(5,6)
第二章：LINQ查询
int[] nums = new int[7] {0,1,2,3,4,5,6 };
//num ：自己定义的局部变量
var result = from num in nums
where num % 2 == 0
select num;
foreach (var item in result)
{
Console.WriteLine(item);
}
//创建对象
public string Name { get; set; }
public string CategoryID { get; set; }
查询所有
List<Products> pList = new List<Products>()
{
new Products{ Name="iphone11",CategoryID="手机"},
new Products{ Name="华为Mate",CategoryID="手机"},
new Products{ Name="小米电视",CategoryID="家电"},
new Products{ Name="运动鞋",CategoryID="鞋子"}
};
var result = from n in pList select n;
foreach (var item in result)
{
Console.WriteLine(item.CategoryID);
Console.WriteLine(item.Name);
}
//列子：假如要查询类别为鞋子的
// var result = from n in pList
// where n.CategoryID=="鞋子"
// select n;
// 查询分组以 类型 ：from n in pLisy group n by n.CategoryID;
/**
foreach (var item in result)
{
Console.WriteLine(item.key);
}
*/
//查询每种产品的数量
var results = from p in pList
group p by p.CategoryID into g
select new {g.Key,ProNums=g.Count() };//ProNums定义数量的名字(随意取)
foreach (var item in results)
{
Console.WriteLine(item.Key);
Console.WriteLine(item.ProNums);
}
排序查询
-
//创建对象 public string LastName { get; set; } public string TitleOfCourtesy { get; set; }
List<Employees> eList = new List<Employees>()
{
new Employees{LastName="王二",TitleOfCourtesy="助理设计师"},
new Employees{LastName="张三",TitleOfCourtesy="软件设计师"},
new Employees{LastName="李四",TitleOfCourtesy="助理设计师"},
new Employees{LastName="王五",TitleOfCourtesy="系统设计师"},
new Employees{LastName="赵六",TitleOfCourtesy="系统分析师"}
};
var result = from p in eList
orderby p.TitleOfCourtesy //descending
select p;
//降序：descending
//第二种写法
//var results = from p in eList
// select new
// {
// LastName = p.LastName,
// Title = p.TitleOfCourtesy
// } into e
// orderby e.Title
// select e;
foreach (var item in result)
{
Console.WriteLine("{0},{1}",item.LastName,item.TitleOfCourtesy);
}
列式编程查询
//查询里面有"a"
string[] names = { "Toms", "jack", "Dick", "Harry", "Mary" };
IEnumerable<string> res=
names.Where(n => n.Contains('a'))
.OrderBy(n => n.Length)
.Select(n => n.ToUpper());
foreach (var item in res)
{
Console.WriteLine(item);
}
查询特有字段
- 添加对象
List<Student> students = new List<Student>
{
new Student {First="Svetlana", Last="Omelchenko", ID=111, Scores= new List<int> {97, 92, 81, 60}},
new Student {First="Claire", Last="ODonnell", ID=112, Scores= new List<int> {75, 84, 91, 39}},
new Student {First="Sven", Last="Mortensen", ID=113, Scores= new List<int> {88, 94, 65, 91}},
new Student {First="Cesar", Last="Garcia", ID=114, Scores= new List<int> {97, 89, 85, 82}},
new Student {First="Debra", Last="Garcia", ID=115, Scores= new List<int> {35, 72, 91, 70}},
new Student {First="Fadi", Last="Fakhouri", ID=116, Scores= new List<int> {99, 86, 90, 94}},
new Student {First="Hanying", Last="Feng", ID=117, Scores= new List<int> {93, 92, 80, 87}},
new Student {First="Hugo", Last="Garcia", ID=118, Scores= new List<int> {92, 90, 83, 78}},
new Student {First="Lance", Last="Tucker", ID=119, Scores= new List<int> {68, 79, 88, 92}},
new Student {First="Terry", Last="Adams", ID=120, Scores= new List<int> {99, 82, 81, 79}},
new Student {First="Eugene", Last="Zabokritski", ID=121, Scores= new List<int> {96, 85, 91, 60}},
new Student {First="Michael", Last="Tucker", ID=122, Scores= new List<int> {94, 92, 91, 91}}
};
求平均值（查询特有的字段）
//求平均值（查询特有的字段）
var resus = students.Select(s => new
{
first = s.First,
last = s.Last,
score = s.Scores.Average()//平均方法
});
foreach (var item in resus)
{
Console.WriteLine("{0},{1},{2}",item.first,item.last,item.score);
}
-
FirstOrDefault：返回第一个元素，没有则返回默认值
-
var s = students.FirstOrDefault(); if(s!=null){ console.writeLine("{0},{1}",s.First,s.Last) } LastOrDefault()//：返回最后一个元素，没有则返回默认值 students.ElementAtOrDefault(5)//返回索引为5的，没有则返回默认值
数据转换操作
-
转换集合：ToList()
-
//查出平均分>85的学生，并将结果转为List集合 //students：上面的添加的对象 List<Student> r = students.Where(c => c.Scores.Average() > 85).ToList();//假如List<student>换成ArrayList(); //用Cast<Student>()强转换 students.Cast<Student>() -
转换不满足的条件的过滤转换
-
var results=students.OfType<Student>(.where)//除了Student都会过滤掉
第三章：ORM数据框架技术
ORM增删改查操作
查询数据库里面的值，并且绑定表
-
using (meixinEntities db=new meixinEntities()) { var data = db.m_user.ToList(); this.GridView1.DataSource = data; DataBind(); }
添加数据库数据：Add
m_user _User = new m_user();
_User.email = "3024888569@qq.com";
_User.pwd = "123456";
_User.logintime = DateTime.Now;
db.m_user.Add(_User);//添加
db.SaveChanges();//保存更改
Response.Write("成功");
删除对象，数据库
int id=int.Parse(this.GridView1.Rows[e.RowIndex].Cells[0].Text);
//m_user _User = new m_user();
//_User.id =Convert.ToInt32(id);
using (meixinEntities db=new meixinEntities())
{
var user = db.m_user.FirstOrDefault(n => n.id == id);//获取满足该条件的第一条数据
db.m_user.Remove(user);
db.SaveChanges();
}
NewMethod();//重新获取页面
修改数据：GridView1
protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
{
this.GridView1.EditIndex = -1;
NewMethod();//重新获取页面
}
protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
this.GridView1.EditIndex = e.NewEditIndex;
NewMethod();//重新获取页面
}
protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
int id = Convert.ToInt32(this.GridView1.Rows[e.RowIndex].Cells[0].Text);
using (meixinEntities db = new meixinEntities())
{
var user= db.m_user.FirstOrDefault(n => n.id == id);
user.pwd = ((TextBox)(this.GridView1.Rows[e.RowIndex].Cells[2].Controls[0])).Text;
user.email = ((TextBox)(this.GridView1.Rows[e.RowIndex].Cells[1].Controls[0])).Text;
user.logintime = Convert.ToDateTime(((TextBox） (this.GridView1.Rows[e.RowIndex].Cells[3].Controls[0])).Text);
db.SaveChanges();//保存修改
}
this.GridView1.EditIndex = -1;
NewMethod();//重新获取页面
}
ORM增删改查多表
绑定下拉菜单
第四章：利用EF进行sql执行
数据库方面
Database.ExecuteSqlCommand ：增删改
using(EFTestEntities db=new EFTestEntities())
{
string sql = $"create table Admin(id int primary key not null," +
"Account varchar(16)," +
"password varchar(20))";
var result = db.Database.ExecuteSqlCommand(sql);
Console.WriteLine(result);
}
添加数据
string sql = "insert into Admin values" +
"(1,'张三','zm123')" +
",(2,'李四','lmm123')";
var result = db.Database.ExecuteSqlCommand(sql);
Console.WriteLine(result);
修改数据 进行传参
- @pwd1,@id1为参数占位符
string sql = @"update Admin set password = @pwd1 where id = @id1";
SqlParameter[] parm = new SqlParameter[]
{
new SqlParameter("@pwd1","123456"),
new SqlParameter("@id1",1)
};
var res = db.Database.ExecuteSqlCommand(sql,parm);
Console.WriteLine(res);
删除数据
-
string sql = "delete from Admin where id=2"; var result = db.Database.ExecuteSqlCommand(sql);
查询数据:SqlQuery
string sql = "select * from Admin where id>=1 order by account desc";
var data = db.Database.SqlQuery<Admin>(sql);
foreach (var item in data)
{
Console.WriteLine("{0},{1},{2}",item.id,item.password,item.Account);
}
查询行数:int
//string sql = "select * from Admin where id>=1 order by account desc";
//var data = db.Database.SqlQuery<Admin>(sql);
//int count = data.ToList().Count;
//Console.WriteLine(count);
//foreach (var item in data)
//{
// Console.WriteLine("{0},{1},{2}",item.id,item.password,item.Account);
//}
string sql = "select count(*) from Admin ";
var data = db.Database.SqlQuery<int>(sql);
foreach (var item in data)
{
Console.WriteLine("{0}",item);
}
查询后进行更新
string sql = "select * from Admin where id>=1 order by account desc";
var data = db.Database.SqlQuery<Admin>(sql).FirstOrDefault();
data.password = "123123";
db.Entry<Admin>(data).State = System.Data.Entity.EntityState.Modified;//传递状态已经被修改
db.SaveChanges();//保存修改
调用存储过程
var admin = db.getAdmin(2).ToList().FirstOrDefault();
Console.WriteLine("{0},{1},{2}",admin.id,admin.password,admin.Account);
调用增加数据的存储过程
- 在数据模型中更新，添加了存储过程后才能调用
int num = db.getInsert(6, "yuanxiao", "131316");
Console.WriteLine(num);//行数
code first模式
-
先创建对象类
-
//用户类 class User { public int Id { get; set; } public string Email { get; set; } public string pwd { get; set; } public Nullable<DateTime> LoginTime { get; set; } public virtual ICollection<order> Order { get; set; } }//创建订单对象 class order { public int id { get; set; } public string phone { get; set; } public string address { get; set; } public string message { get; set; } public string status { get; set; } public Nullable<System.DateTime> orderTime { get; set; } public virtual User user { get; set; } }- 引入空的code first模型
- 编写代码
class MexinContext:DbContext { public MexinContext():base("name=Mexin") { } //这是先前创建的对象类，与之关联，返回DbSet public virtual DbSet<User> Users { get; set; } // virtual导航属性 默认会有延迟加载 public virtual ICollection<order> Order { get; set; } }-
在app.config里面添加
-
<connectionStrings> <add name="Model1" connectionString="data source=(LocalDb)\MSSQLLocalDB;initial catalog=Task4._4.Model1;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" /> <!--在这里面重复添加，name与之前的类：base("name=Mexin")一致 把(LocalDb)\MSSQLLocalDB改成 . --> <add name="Meixin" connectionString="data source=.;initial catalog=Model1;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework" providerName="System.Data.SqlClient" /> </connectionStrings> <!--连接属性-->-
创建class InitDatabase
-
class InitDatabase:DropCreateDatabaseIfModelChanges<MexinContext> { protected override void Seed(MexinContext context) { //base.Seed(context); User user = new User() { Id = 2, Email = "ym@163.com", pwd = "123654", LoginTime = DateTime.Now }; context.Users.Add(user); context.SaveChanges(); Console.WriteLine("挺好的"); } }
-
延迟加载的启动和关闭
db.Configuration.LazyLoadingEnabled = false;//关闭延迟加载,反则false
贪婪加载
var data = db.m_user.Include("m_order").FirstOrDefault(p => p.id == 1);
显示加载
var data = db.m_user..FirstOrDefault(p => p.id == 1);
db.Entry(data).Collection("m_order").Load();
第五章：理解.net运行机制
1.创建请求前后的方法
- 创建类
public class TextModule : IHttpModule
{
public void Dispose()
{
throw new NotImplementedException();
}
public void Init(HttpApplication context)
{
//handler处理请求前的执行方法begin
context.BeginRequest += begin;
//handler处理请求后的执行方法end
context.EndRequest += end;
}
private void end(object sender, EventArgs e)
{
HttpApplication application = sender as HttpApplication;
application.Response.Write("<p>module结束处理请求</p>");
}
private void begin(object sender, EventArgs e)
{
HttpApplication application = sender as HttpApplication;
application.Response.Write("<p>module开始处理请求</p>");
}
}
- 在配置web.config里面配置
<system.webServer>
<modules>
<add name="test" type="demo5_.TextModule"/>
//demo5_是路径
</modules>
</system.webServer>
2.盗链：
-
因为盗链是一个不好的行为，我们就防止此事件发生
-
创建Handler1.ashx：一般处理程序
-
public class Handler1 : IHttpHandler { public void ProcessRequest(HttpContext context) { //返回上一次访问的请求 Uri lasturl= context.Request.UrlReferrer; //返回本次的请求地址 Uri uri = context.Request.Url; if (lasturl.Host != uri.Host||lasturl.Port!=uri.Port) { //如果两个不太一致，说明盗链 string errulr= context.Request.PhysicalApplicationPath + "Error/default.jpg"; context.Response.WriteFile(errulr); //Error/default.jpg：是事先准备的被盗的图片 } else { string errulr1 = context.Request.PhysicalApplicationPath; context.Response.WriteFile(errulr1); } } public bool IsReusable { get { return false; } } }- 然后配置web.comfig
第六章：AjAX前后台交互
重写URL
-
编写虚拟的地址
-
<ul> <li> <a href="Goods_1.html">服装</a> </li> <li> <a href="Goods_2.html">商品</a> </li> </ul>-
编写获取接口的
-
public class RewriteModule : IHttpModule { public void Dispose() { throw new NotImplementedException(); } public void Init(HttpApplication context) { context.BeginRequest += rewriteUrl; } private void rewriteUrl(object sender, EventArgs e) { //1.获取地址 HttpApplication application= sender as HttpApplication; string res = application.Request.RawUrl; //2.为了安全，编写正则表达式、 Regex regex = new Regex(@"\w+_\d+\.html"); if (regex.IsMatch(res)) { int numline = res.LastIndexOf("_"); int dot = res.LastIndexOf("."); //截取地址里面的id数字 string id = res.Substring(numline + 1, dot -numline- 1); //重新组装地址 string reaurl = "~/GoodsList.aspx?id" + id; application.Server.Transfer(reaurl);//Transfer:终止当前页的地址，传入一个新的地址，并且调转 }} }- 配置文件 - ```c# <system.webServer> <modules> <add name="ets" type="Test6._1.RewriteModule"/> </modules> </system.webServer>
- 在GoodsList.aspx里面写 - ```c# protected void Page_Load(object sender, EventArgs e) { Response.Write("id=" + Request["id"]); } ```
-
ajax: asp
function showHint(str)
{
var xmlhttp;
if (str.length==0)
{
document.getElementById("txtHint").innerHTML="";
return;
}
if (window.XMLHttpRequest)
{
// IE7+, Firefox, Chrome, Opera, Safari 浏览器执行代码
xmlhttp=new XMLHttpRequest();
}
else
{
// IE6, IE5 浏览器执行代码
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
//onreadystatechange是获取的xmlhttp的状态变化
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById("txtHint").innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","地址"+str,true);
xmlhttp.send();
}
-
解析xml
-
xmlDoc=xmlhttp.responseXML; txt=""; x=xmlDoc.getElementsByTagName("ARTIST"); for (i=0;i<x.length;i++) { txt=txt + x[i].childNodes[0].nodeValue + "<br>"; } document.getElementById("myDiv").innerHTML=txt;
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