C# 在另一个控制器中将责任从短URL重定向到完整URL

作为一个家庭作业，我必须做一个简单的URL缩短器，在这里我可以添加完整的链接到列表，这是由处理，我得到一个URL的简短版本

我现在有了类似的东西，但我一直无法将其重定向回完整链接

我想添加一个新的控制器，它将负责将短URL重定向到完整URL。单击短URL后，它应该转到

localhost:xxxx/ShortenedUrl

，然后重定向到完整链接。有什么建议吗？我该怎么做

我试图通过重定向控制器中的

@Html.ActionLink（@item.ShortenedLink，“Index”，“Redirect”）

和

返回重定向（fullLink）

来实现这一点，但它没有像我预期的那样工作

还有一个关于路由的问题，我怎样才能在点击短URL后获得

localhost:XXXX/ShortenedURL

（即

localhost:XXXX/FSIAOFJO2@

）。现在我有了

<a href="@item.ShortenedLink">@Html.DisplayFor(model => item.ShortenedLink)</a> 

但它给了我

localhost:XXXX/Link/ShortenedURL

，所以我想在URL中省略这个链接

查看（带有短URL的部分）：

重定向我正在尝试执行的控制器：

public class LinkController : Controller
{
    private ILinksRepository _repository;

    public LinkController(ILinksRepository linksRepository)
    {
        _repository = linksRepository;
    }

    [HttpGet]
    public IActionResult Index()
    {
        var links = _repository.GetLinks();
        return View(links);
    }

    [HttpPost]
    public IActionResult Create(Link link)
    {
        _repository.AddLink(link);
        return Redirect("Index");
    }

    [HttpGet]
    public IActionResult Delete(Link link)
    {
        _repository.DeleteLink(link);
        return Redirect("Index");
    }
}

private ILinksRepository _repository;

public RedirectController(ILinksRepository linksRepository)
{
    _repository = linksRepository;
}

public IActionResult GoToFull()
{
    var links = _repository.GetLinks();
    return Redirect(links[0].FullLink);
}

---

是否有更好的方法访问重定向控制器中的链接列表？

这是我的建议，通过AJAX触发链接，下面是一个工作示例：

这是通过模型绑定的HTML元素：

@Html.ActionLink(Model.ShortenedLink, "", "", null, 
new { onclick = "fncTrigger('" + "http://www.google.com" + "');" })

这是javascript ajax代码：

function fncTrigger(id) {

            $.ajax({
                url: '@Url.Action("TestDirect", "Home")',
                type: "GET",
                data: { id: id },
                success: function (e) {
                },
                error: function (err) {
                    alert(err);
                },
            });
    }

然后在您的控制器上，单击以接收ajax：

 public ActionResult TestDirect(string id)
    {
        return JavaScript("window.location = '" + id + "'");
    }

---

基本上，我在这里做的是，单击链接后，它将调用TestDirect操作，然后使用传递的url参数将其重定向到。您可以在此操作中进行转换。

要创建动态数据驱动URL，您需要创建自定义URL。以下是如何做到这一点：

cachedurote

这是一个可重用的泛型类，它将一组动态提供的URL映射到单个操作方法。您可以插入一个

ICachedRouteDataProvider

来提供数据（主键映射的URL）

缓存数据以防止多个同时请求过载数据库（路由在每个请求上运行）。默认缓存时间为15分钟，但您可以根据需要进行调整

如果希望它“立即”运行，可以构建一个更高级的缓存，该缓存在成功更新其中一条记录的数据库后立即更新。也就是说，相同的操作方法将同时更新数据库和缓存

重定向控制器

我们的重定向控制器接受主键作为

id

参数，然后查找数据库记录以获取要重定向到的URL

public class RedirectController
{
    private readonly ApplicationDbContext dbContext;

    public RedirectController(ApplicationDbContext dbContext)
    {
        this.dbContext = dbContext
            ?? throw new ArgumentNullException(nameof(dbContext));
    }

    public IActionResult GoToFull(int id)
    {
        var link = dbContext.Links.FirstOrDefault(x => x.Id == id);
        return new RedirectResult(link.FullLink);
    }
}

在生产场景中，您可能希望使其成为一个永久重定向

返回新的重定向结果（link.FullLink，true）

，但是浏览器会自动缓存这些重定向结果，这使得测试变得困难

Startup.cs

我们在DI容器中设置了

DbContext

、内存缓存和

linkcachedrootedataprovider

，以供以后使用

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddMvc();

    services.AddMemoryCache();
    services.AddSingleton<LinkCachedRouteDataProvider>();
}

我做了一个决定。如果在浏览器中输入短URL，它们将被重定向到长URL

• M81J1w0A

  ->

  https://maps.google.com/

• r33NW8K

  ->

  https://stackoverflow.com/

我没有创建任何视图来更新数据库中的URL，但是这类内容在一些教程中都有介绍，例如，并且看起来您在该部分没有问题

参考资料：

---

它是Asp.Net核心

using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.Caching.Memory;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

public class CachedRoute<TPrimaryKey> : IRouter
{
    private readonly string _controller;
    private readonly string _action;
    private readonly ICachedRouteDataProvider<TPrimaryKey> _dataProvider;
    private readonly IMemoryCache _cache;
    private readonly IRouter _target;
    private readonly string _cacheKey;
    private object _lock = new object();

    public CachedRoute(
        string controller,
        string action,
        ICachedRouteDataProvider<TPrimaryKey> dataProvider,
        IMemoryCache cache,
        IRouter target)
    {
        if (string.IsNullOrWhiteSpace(controller))
            throw new ArgumentNullException("controller");
        if (string.IsNullOrWhiteSpace(action))
            throw new ArgumentNullException("action");
        if (dataProvider == null)
            throw new ArgumentNullException("dataProvider");
        if (cache == null)
            throw new ArgumentNullException("cache");
        if (target == null)
            throw new ArgumentNullException("target");

        _controller = controller;
        _action = action;
        _dataProvider = dataProvider;
        _cache = cache;
        _target = target;

        // Set Defaults
        CacheTimeoutInSeconds = 900;
        _cacheKey = "__" + this.GetType().Name + "_GetPageList_" + _controller + "_" + _action;
    }

    public int CacheTimeoutInSeconds { get; set; }

    public async Task RouteAsync(RouteContext context)
    {
        var requestPath = context.HttpContext.Request.Path.Value;

        if (!string.IsNullOrEmpty(requestPath) && requestPath[0] == '/')
        {
            // Trim the leading slash
            requestPath = requestPath.Substring(1);
        }

        // Get the page id that matches.
        TPrimaryKey id;

        //If this returns false, that means the URI did not match
        if (!GetPageList().TryGetValue(requestPath, out id))
        {
            return;
        }

        //Invoke MVC controller/action
        var routeData = context.RouteData;

        // TODO: You might want to use the page object (from the database) to
        // get both the controller and action, and possibly even an area.
        // Alternatively, you could create a route for each table and hard-code
        // this information.
        routeData.Values["controller"] = _controller;
        routeData.Values["action"] = _action;

        // This will be the primary key of the database row.
        // It might be an integer or a GUID.
        routeData.Values["id"] = id;

        await _target.RouteAsync(context);
    }

    public VirtualPathData GetVirtualPath(VirtualPathContext context)
    {
        VirtualPathData result = null;
        string virtualPath;

        if (TryFindMatch(GetPageList(), context.Values, out virtualPath))
        {
            result = new VirtualPathData(this, virtualPath);
        }

        return result;
    }

    private bool TryFindMatch(IDictionary<string, TPrimaryKey> pages, IDictionary<string, object> values, out string virtualPath)
    {
        virtualPath = string.Empty;
        TPrimaryKey id;
        object idObj;
        object controller;
        object action;

        if (!values.TryGetValue("id", out idObj))
        {
            return false;
        }

        id = SafeConvert<TPrimaryKey>(idObj);
        values.TryGetValue("controller", out controller);
        values.TryGetValue("action", out action);

        // The logic here should be the inverse of the logic in 
        // RouteAsync(). So, we match the same controller, action, and id.
        // If we had additional route values there, we would take them all 
        // into consideration during this step.
        if (action.Equals(_action) && controller.Equals(_controller))
        {
            // The 'OrDefault' case returns the default value of the type you're 
            // iterating over. For value types, it will be a new instance of that type. 
            // Since KeyValuePair<TKey, TValue> is a value type (i.e. a struct), 
            // the 'OrDefault' case will not result in a null-reference exception. 
            // Since TKey here is string, the .Key of that new instance will be null.
            virtualPath = pages.FirstOrDefault(x => x.Value.Equals(id)).Key;
            if (!string.IsNullOrEmpty(virtualPath))
            {
                return true;
            }
        }
        return false;
    }

    private IDictionary<string, TPrimaryKey> GetPageList()
    {
        IDictionary<string, TPrimaryKey> pages;

        if (!_cache.TryGetValue(_cacheKey, out pages))
        {
            // Only allow one thread to poplate the data
            lock (_lock)
            {
                if (!_cache.TryGetValue(_cacheKey, out pages))
                {
                    pages = _dataProvider.GetPageToIdMap();

                    _cache.Set(_cacheKey, pages,
                        new MemoryCacheEntryOptions()
                        {
                            Priority = CacheItemPriority.NeverRemove,
                            AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(this.CacheTimeoutInSeconds)
                        });
                }
            }
        }

        return pages;
    }

    private static T SafeConvert<T>(object obj)
    {
        if (typeof(T).Equals(typeof(Guid)))
        {
            if (obj.GetType() == typeof(string))
            {
                return (T)(object)new Guid(obj.ToString());
            }
            return (T)(object)Guid.Empty;
        }
        return (T)Convert.ChangeType(obj, typeof(T));
    }
}

public interface ICachedRouteDataProvider<TPrimaryKey>
{
    IDictionary<string, TPrimaryKey> GetPageToIdMap();
}

public class LinkCachedRouteDataProvider : ICachedRouteDataProvider<int>
{
    private readonly IServiceProvider serviceProvider;

    public LinkCachedRouteDataProvider(IServiceProvider serviceProvider)
    {
        this.serviceProvider = serviceProvider
            ?? throw new ArgumentNullException(nameof(serviceProvider));
    }

    public IDictionary<string, int> GetPageToIdMap()
    {
        using (var scope = serviceProvider.CreateScope())
        {
            var dbContext = scope.ServiceProvider.GetService<ApplicationDbContext>();

            return (from link in dbContext.Links
                    select new KeyValuePair<string, int>(
                        link.ShortenedLink.Trim('/'),
                        link.Id)
                    ).ToDictionary(pair => pair.Key, pair => pair.Value);
        }
    }
}

public class RedirectController
{
    private readonly ApplicationDbContext dbContext;

    public RedirectController(ApplicationDbContext dbContext)
    {
        this.dbContext = dbContext
            ?? throw new ArgumentNullException(nameof(dbContext));
    }

    public IActionResult GoToFull(int id)
    {
        var link = dbContext.Links.FirstOrDefault(x => x.Id == id);
        return new RedirectResult(link.FullLink);
    }
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApplicationDbContext>(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddMvc();

    services.AddMemoryCache();
    services.AddSingleton<LinkCachedRouteDataProvider>();
}

app.UseMvc(routes =>
{
    routes.Routes.Add(new CachedRoute<int>(
        controller: "Redirect",
        action: "GoToFull",
        dataProvider: app.ApplicationServices.GetService<LinkCachedRouteDataProvider>(),
        cache: app.ApplicationServices.GetService<IMemoryCache>(),
        target: routes.DefaultHandler)
        // Set to 60 seconds of caching to make DB updates refresh quicker
        { CacheTimeoutInSeconds = 60 });

    routes.MapRoute(
        name: "default",
        template: "{controller=Home}/{action=Index}/{id?}");
});

<a asp-area="" asp-controller="Redirect" asp-action="GoToFull" asp-route-id="1">
    @Url.Action("GoToFull", "Redirect", new { id = 1 })
</a>

<a href="/M81J1w0A">/M81J1w0A</a>

<a asp-area="" asp-controller="Redirect" asp-action="GoToFull" asp-route-id="@Model.Id">
    @Url.Action("GoToFull", "Redirect", new { id = Model.Id })
</a>