using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Runtime.Caching;
using System.Text;
using System.Web;
using System.Web.Http.Filters;
namespace SH3H.WAP.WorkSheet.Outgoing.WebApi.Filters
{
/// <summary>
/// 定义过滤2s内重复提交的action
/// </summary>
[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false)]
public class FWActionSubmitFilterAttribute : ActionFilterAttribute
{
MemoryCacheHelper _cache = new MemoryCacheHelper();
/// <summary>
/// 客户端缓存（用户代理）缓存相对过期时间
/// </summary>
public int ClientCacheExpiration { set; get; }
/// <summary>
/// 服务端缓存过期时间
/// </summary>
public int ServerCacheExpiration { set; get; }
/// <summary>
///
/// </summary>
/// <param name="clientCacheExpiration">客户端过期时间。单位为秒，默认为600秒(10分钟)</param>
/// <param name="serverCacheExpiration">服务端过期时间。单位为秒，默认为7200秒(120分钟)</param>
public FWActionSubmitFilterAttribute(int clientCacheExpiration = 10, int serverCacheExpiration = 30)
{
this.ClientCacheExpiration = clientCacheExpiration;
this.ServerCacheExpiration = serverCacheExpiration;
}
/// <summary>
/// 判定是否用缓存中的内容，还是执行action是去取内容
/// 注：一旦给actionContext.Response赋值了，则会使用这个值来输出响应
/// </summary>
/// <param name="actionContext"></param>
public override void OnActionExecuting(System.Web.Http.Controllers.HttpActionContext actionContext)
{
// **************************************** 穿透缓存 *********************************************
// 若无缓存,则直接返回
string cacheKey = getCacheKey(actionContext);
if (_cache.Contains(cacheKey) == false)
return;
if (_cache.Contains(cacheKey + ":etag") == false)
return;
// **************************************** 使用缓存 *********************************************
// 获取缓存中的etag
var etag = _cache.Get<string>(cacheKey + ":etag");
// 若etag没有被改变，则返回304，
if (actionContext.Request.Headers.IfNoneMatch.Any(x => x.Tag == etag)) //IfNoneMatch为空时，返回的是一个集合对象
{
actionContext.Response = actionContext.Request.CreateResponse(HttpStatusCode.NotModified); // 响应对象还没有生成，需要先生成 // 304 not modified
actionContext.Response.Headers.CacheControl = GetDefaultCacheControl();
actionContext.Response.Headers.ETag = new EntityTagHeaderValue(etag);
return;
}
else //从缓存中返回响应
{
actionContext.Response = actionContext.Request.CreateResponse(); // 响应对象还没有生成，需要先生成
// 设置协商缓存：etag
actionContext.Response.Headers.ETag = new EntityTagHeaderValue(etag); //用缓存中的值（为最新的）更新它
// 设置user agent的本地缓存
actionContext.Response.Headers.CacheControl = GetDefaultCacheControl();
// 从缓存中取中响应内容
var content = _cache.Get<byte[]>(cacheKey);
actionContext.Response.Content = new ByteArrayContent(content);
return;
}
}
/// <summary>
/// 将输出保存在缓存中。
/// </summary>
/// <param name="actionExecutedContext"></param>
/// <param name="cancellationToken"></param>
/// <returns></returns>
public override async System.Threading.Tasks.Task OnActionExecutedAsync(HttpActionExecutedContext actionExecutedContext, System.Threading.CancellationToken cancellationToken)
{
// 响应对象已经生成，可以直接调用 actionExecutedContext.Response
// 设置协商缓存：etag
EntityTagHeaderValue etag = new EntityTagHeaderValue("\"" + Guid.NewGuid().ToString() + "\""); // 根据http协议， ETag的值必须用引号包含起来
actionExecutedContext.Response.Headers.ETag = etag;
// 设置user agent的本地缓存
actionExecutedContext.Response.Headers.CacheControl = GetDefaultCacheControl();
// actionExecutedContext.Response.Headers.Remove("Content-Length"); // 改变了值，它会发生变化。删除它的话，后续的程序会自动地再计算
// 保存到缓存
string cacheKey = getCacheKey(actionExecutedContext.ActionContext);
var contentBytes = await actionExecutedContext.Response.Content.ReadAsByteArrayAsync();
_cache.Add(cacheKey + ":etag", etag.Tag, DateTimeOffset.Now.AddSeconds(this.ServerCacheExpiration));
_cache.Add(cacheKey, contentBytes, DateTimeOffset.Now.AddSeconds(this.ServerCacheExpiration));
}
/// <summary>
/// 默认的用户代理本地缓存配置，10分钟的相对过期时间
/// 对应响应header中的 Cache-Control
/// 这里设置里面的子项max-age。如：Cache-Control: max-age=3600
/// </summary>
/// <returns></returns>
CacheControlHeaderValue GetDefaultCacheControl()
{
CacheControlHeaderValue control = new CacheControlHeaderValue();
control.MaxAge = TimeSpan.FromSeconds(this.ClientCacheExpiration); // 它对应响应头中的 cacheControl :max-age=10项
return control;
}
/// <summary>
///
/// </summary>
/// <param name="actionContext"></param>
/// <returns></returns>
string getCacheKey(System.Web.Http.Controllers.HttpActionContext actionContext)
{
string cacheKey = null;
//获取POST中data
var context = (HttpContextBase)actionContext.Request.Properties["MS_HttpContext"];
context.Request.InputStream.Seek(0, SeekOrigin.Begin);
using (var sr = new StreamReader(context.Request.InputStream, Encoding.UTF8, true, 1024, true))
{
string body = sr.ReadToEnd();
// Logging here...
}
cacheKey = actionContext.Request.RequestUri.PathAndQuery; // 路径和查询部分,如： /api/values/1?ee=33&oo=5
// 对路径中的参数进行重排，升序排列
string controllerName = actionContext.ControllerContext.ControllerDescriptor.ControllerName;
string actionName = actionContext.ActionDescriptor.ActionName;
if (actionContext.ActionArguments.ContainsKey("id") == false)
{
cacheKey = controllerName + "/" + actionName;
}
else
{
string id = actionContext.ActionArguments["id"].ToString();
cacheKey = controllerName + "/" + actionName + "/" + id;
}
return cacheKey;
}
}
/// <summary>
/// 缓存辅助类
/// </summary>
public class MemoryCacheHelper
{
private static readonly MemoryCache _cache = MemoryCache.Default;
/// <summary>
///
/// </summary>
/// <param name="key"></param>
public void RemoveStartsWith(string key)
{
lock (_cache)
{
_cache.Remove(key);
}
}
/// <summary>
///
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="key"></param>
/// <returns></returns>
public T Get<T>(string key) where T : class
{
var o = _cache.Get(key) as T;
return o;
}
/// <summary>
///
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
[Obsolete("Use Get<T> instead")]
public object Get(string key)
{
return _cache.Get(key);
}
/// <summary>
///
/// </summary>
/// <param name="key"></param>
public void Remove(string key)
{
lock (_cache)
{
_cache.Remove(key);
}
}
/// <summary>
///
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public bool Contains(string key)
{
return _cache.Contains(key);
}
/// <summary>
///
/// </summary>
/// <param name="key"></param>
/// <param name="o"></param>
/// <param name="expiration"></param>
/// <param name="dependsOnKey"></param>
public void Add(string key, object o, DateTimeOffset expiration, string dependsOnKey = null)
{
var cachePolicy = new CacheItemPolicy
{
AbsoluteExpiration = expiration
};
if (!string.IsNullOrWhiteSpace(dependsOnKey))
{
cachePolicy.ChangeMonitors.Add(
_cache.CreateCacheEntryChangeMonitor(new[] { dependsOnKey })
);
}
lock (_cache)
{
_cache.Add(key, o, cachePolicy);
}
}
/// <summary>
///
/// </summary>
public IEnumerable<string> AllKeys
{
get
{
return _cache.Select(x => x.Key);
}
}
}
}
