MVC缓存02,使用数据层缓存,添加或修改时让缓存失效

分手后的思念是犯贱 2021-10-23 11:28 215阅读 0赞

在"[MVC缓存01,使用控制器缓存或数据层缓存][MVC_01]"中，在数据层中可以设置缓存的有效时间。但这个还不够"智能"，常常希望在编辑或创建的时候使缓存失效，加载新的数据。

**□ 思路**

1、缓存是以键值<string, object>存放的，在创建缓存的时候，先把IDictionary<int,T>作为缓存内容存储,int为T的主键。  
[![14][]][14 1]

2、EF上下文保存的时候时候把变化保存到数据库，并更新缓存中的内容。

● 先找出上下文中状态为added或modified的实体：var changeobjects  
● 把变化保存数据到数据库：context.SaveChanges()  
● 根据缓存key获取类型为IDictionary<int,T>的缓存内容：var cacheData = Cache.Get("vehicles") as Dictionary<int, Vehicle>;  
● 最后遍历这些变化的实体，更新缓存项：cacheData\[vehicle.Id\] = vehicle;

**□ 缓存接口**

public interface ICacheProvider

{

object Get(string key);

void Set(string key, object data, int cacheTime);

bool IsSet(string key);

void Invalidate(string key);

}

**□ 缓存接口实现**

围绕using System.Runtime.Caching的MemoryCache.Default返回类型为ObjectCache的缓存属性实现缓存接口：获取缓存项、设置缓存、判断是否设置缓存、清空缓存。

using System;

using System.Runtime.Caching;

namespace MvcApplication1.Cache

{

public class DefaultCacheProvider : ICacheProvider

{

private ObjectCache Cache

{

get { return MemoryCache.Default; }

}

public object Get(string key)

{

return Cache[key];

}

public void Set(string key, object data, int cacheTime)

{

CacheItemPolicy policy = new CacheItemPolicy();

policy.AbsoluteExpiration = DateTime.Now + TimeSpan.FromMinutes(cacheTime);

Cache.Add(new CacheItem(key, data), policy);

}

public bool IsSet(string key)

{

return (Cache[key] != null);

}

public void Invalidate(string key)

{

Cache.Remove(key);

}

**□ Model**

public partial class Vehicle

{

public int Id { get; set; }

public string Name { get; set; }

public decimal Price { get; set; }

}

**□ 针对Vehicle的Repositoy接口：**

using System.Collections.Generic;

using MvcApplication1.Models;

namespace MvcApplication1.Repository

{

public interface IVehicleRepository

{

void ClearCache();

IEnumerable<Vehicle> GetVehicles();

void Insert(Vehicle vehicle);

void Update(Vehicle vehicle);

void SaveChanges();

}

**□ 针对Vehicle的Repositoy接口实现：**

using System.Collections.Generic;

using System.Data;

using System.Data.Entity.Infrastructure;

using System.Linq;

using MvcApplication1.Cache;

using MvcApplication1.Models;

namespace MvcApplication1.Repository

{

public class VehicleRepository : IVehicleRepository

{

protected DemoEntities DataContext { get; private set; }

public ICacheProvider Cache { get; set; }

public VehicleRepository() : this(new DefaultCacheProvider())

{

}

public VehicleRepository(ICacheProvider cacheProvider)

{

this.DataContext = new DemoEntities();

this.Cache = cacheProvider;

}

public void ClearCache()

{

Cache.Invalidate("vehicles");

}

public System.Collections.Generic.IEnumerable<Models.Vehicle> GetVehicles()

{

var vehicles = Cache.Get("vehicles") as IDictionary<int, Vehicle>;

if (vehicles == null)

{

vehicles = DataContext.Vehicle.ToDictionary(v => v.Id);

if (vehicles.Any())

{

Cache.Set("vehicles",vehicles,30);

}

return vehicles.Values;

}

public void Update(Vehicle vehicle)

{

if (vehicle != null)

{

DataContext.Set<Vehicle>().Attach(vehicle);

DataContext.Entry(vehicle).State = EntityState.Modified;

}

public void Insert(Vehicle vehicle)

{

DataContext.Set<Vehicle>().Add(vehicle);

}

public void SaveChanges()

{

//获取上下文中EntityState状态为added或modified的Vehicle

var changeobjects = DataContext.ChangeTracker.Entries<Vehicle>();

//把变化保存到数据库

DataContext.SaveChanges();

//更新缓存中相关的Vehicle

var cacheData = Cache.Get("vehicles") as Dictionary<int, Vehicle>;

if (cacheData != null)

{

foreach (var item in changeobjects)

{

var vehicle = item.Entity as Vehicle;

cacheData[vehicle.Id] = vehicle;

}

在保存缓存Cache.Set("vehicles",vehicles,30)之前，把从上下文获取到的数据转换成IDictionary<int,T>类型vehicles = DataContext.Vehicle.ToDictionary(v => v.Id);

**□ HomeController**

using System.Linq;

using System.Web;

using System.Web.Mvc;

using MvcApplication1.Models;

using MvcApplication1.Repository;

namespace MvcApplication1.Controllers

{

public class HomeController : Controller

{

public IVehicleRepository Repository { get; set; }

public HomeController(IVehicleRepository repository)

{

this.Repository = repository;

}

public HomeController() : this(new VehicleRepository())

{

}

public ActionResult Index()

{

return View(Repository.GetVehicles());

}

[HttpPost]

public ActionResult Index(FormCollection form)

{

Repository.ClearCache();

return RedirectToAction("Index");

}

public ActionResult Edit(int id)

{

var vehicle = Repository.GetVehicles().Single(v => v.Id == id);

return View(vehicle);

}

[HttpPost]

public ActionResult Edit(Vehicle vehicle)

{

Repository.Update(vehicle);

Repository.SaveChanges();

return RedirectToAction("Index");

}

public ActionResult Create()

{

return View(new Vehicle());

}

[HttpPost]

public ActionResult Create(Vehicle vehicle)

{

Repository.Insert(vehicle);

Repository.SaveChanges();

return RedirectToAction("Index");

}

**□ Home/Index.cshtml**

@model IEnumerable<MvcApplication1.Models.Vehicle>

ViewBag.Title = "Index";

Layout = "~/Views/Shared/_Layout.cshtml";

}

table td {

border-collapse: collapse;

border: solid 1px black;

}

</style>

<tr>

</tr>

@foreach (var vehicle in Model)

{

<tr>

<td>@vehicle.Id.ToString()</td>

<td>@vehicle.Name</td>

<td>@string.Format("{0:c}",vehicle.Price)</td>

<td>

@Html.ActionLink("编辑", "Edit", new { id=vehicle.Id })

</td>

</tr>

}

</table>

@using (Html.BeginForm())

{

}

<p>

@Html.ActionLink("创建", "Create")

</p>

**□ Home/Create.cshtml**

展开@model MvcApplication1.Models.Vehicle
    
    @{
        ViewBag.Title = "Create";
        Layout = "~/Views/Shared/_Layout.cshtml";
    }
    
    <h2>Create</h2>
    
    @using (Html.BeginForm()) {
        @Html.ValidationSummary(true)
    
        <fieldset>
            <legend>Vehicle</legend>
    
            <div class="editor-label">
                @Html.LabelFor(model => model.Name)
            </div>
            <div class="editor-field">
                @Html.EditorFor(model => model.Name)
                @Html.ValidationMessageFor(model => model.Name)
            </div>
    
            <div class="editor-label">
                @Html.LabelFor(model => model.Price)
            </div>
            <div class="editor-field">
                @Html.EditorFor(model => model.Price)
                @Html.ValidationMessageFor(model => model.Price)
            </div>
    
            <p>
                <input type="submit" value="Create" />
            </p>
        </fieldset>
    }
    
    @section Scripts {
        @Scripts.Render("~/bundles/jqueryval")
    }

**□ Home/Edit.cshtml**

展开@model MvcApplication1.Models.Vehicle
    
    @{
        ViewBag.Title = "Edit";
        Layout = "~/Views/Shared/_Layout.cshtml";
    }
    
    <h2>Edit</h2>
    
    @using (Html.BeginForm()) {
        @Html.ValidationSummary(true)
    
        <fieldset>
            <legend>Vehicle</legend>
    
            @Html.HiddenFor(model => model.Id)
    
            <div class="editor-label">
                @Html.LabelFor(model => model.Name)
            </div>
            <div class="editor-field">
                @Html.EditorFor(model => model.Name)
                @Html.ValidationMessageFor(model => model.Name)
            </div>
    
            <div class="editor-label">
                @Html.LabelFor(model => model.Price)
            </div>
            <div class="editor-field">
                @Html.EditorFor(model => model.Price)
                @Html.ValidationMessageFor(model => model.Price)
            </div>
    
            <p>
                <input type="submit" value="Save" />
            </p>
        </fieldset>
    }
    
    
    @section Scripts {
        @Scripts.Render("~/bundles/jqueryval")
    }

**□ 结果：**

创建或修改之前：  
[![10][]][10 1]

编辑更新：  
[![11][]][11 1]

创建：  
[![12][]][12 1]

编辑创建成功后：  
[![13][]][13 1]

□ 参考资料  
※ [DATA CACHING WITH .NET 4.0 AND ASP.NET MVC – PART 2][DATA CACHING WITH .NET 4.0 AND ASP.NET MVC _ PART 2]

转载于:https://www.cnblogs.com/darrenji/p/3649994.html

[MVC_01]: http://www.cnblogs.com/darrenji/p/3644929.html
[14]: /images/20211023/283faa95e9834cf7a16216576cc190b0.png
[14 1]: https://images0.cnblogs.com/blog/417212/201404/071234229034200.png
[10]: /images/20211023/85f753d7007d4fb7a4b1dc07e1576b2a.png
[10 1]: https://images0.cnblogs.com/blog/417212/201404/071234240909971.png
[11]: /images/20211023/14d84defbe1b4462b8c34bb7746066a9.png
[11 1]: https://images0.cnblogs.com/blog/417212/201404/071234252316055.png
[12]: /images/20211023/6c967e1ca83f42049642e3e18665258d.png
[12 1]: https://images0.cnblogs.com/blog/417212/201404/071234260755398.png
[13]: /images/20211023/43d83b28c7ec456c838bd84eb86a1b39.png
[13 1]: https://images0.cnblogs.com/blog/417212/201404/071234273721669.png
[DATA CACHING WITH .NET 4.0 AND ASP.NET MVC _ PART 2]: http://stevescodingblog.co.uk/net4-caching-with-mvc-2/