本文转自:http://www.cnblogs.com/TomXu/p/4496445.html
在之前的版本中,Session存在于System.Web中,新版ASP.NET 5中由于不在依赖于System.Web.dll库了,所以相应的,Session也就成了ASP.NET 5中一个可配置的模块(middleware)了。
配置启用Session
ASP.NET 5中的Session模块存在于Microsoft.AspNet.Session类库中,要启用Session,首先需要在project.json中的dependencies节点中添加如下内容:
"Microsoft.AspNet.Session": "1.0.0-beta3"
然后在ConfigureServices中添加Session的引用(并进行配置):
services.AddCaching(); // 这两个必须同时添加,因为Session依赖于Caching
services.AddSession();
//services.ConfigureSession(null); 可以在这里配置,也可以再后面进行配置
最后在Configure方法中,开启使用Session的模式,如果在上面已经配置过了,则可以不再传入配置信息,否则还是要像上面的配置信息一样,传入Session的配置信息,代码如下:
app.UseInMemorySession(configure:s => { s.IdleTimeout = TimeSpan.FromMinutes(30); });
//app.UseSession(o => { o.IdleTimeout = TimeSpan.FromSeconds(30); });
//app.UseInMemorySession(null, null); //开启内存Session
//app.UseDistributedSession(null, null);//开启分布式Session,也即持久化Session //app.UseDistributedSession(new RedisCache(new RedisCacheOptions() { Configuration = "localhost" }));
对于UseInMemorySession方法,接收2个可选参数,分别是:IMemoryCache
可用于修改Session数据的默认保存地址;Action<SessionOptions>
委托则可以让你修改默认选项,比如Session cookie的路径、默认的过期时间等。本例中,我们修改默认过期时间为30分钟。
注意:该方法必须在app.UseMvc之前调用,否则在Mvc里获取不到Session,而且会出错。
获取和设置Session
获取和设置Session对象,一般是在Controller的action里通过this.Context.Session
来获取的,其获取的是一个基于接口ISessionCollection
的实例。该接口可以通过索引、Set、TryGetValue等方法进行Session值的获取和设置,但我们发现在获取和设置Session的时候,我们只能使用byte[]类型,而不能像之前版本的Session一样可以设置任意类型的数据。原因是因为,新版本的Session要支持在远程服务器上存储,就需要支持序列化,所以才强制要求保存为byte[]
类型。所以我们在保存Session的时候,需要将其转换为byte[]
才能进行保存,并且获取以后要再次将byte[]
转换为自己的原有的类型才行。这种形式太麻烦了,好在微软在Microsoft.AspNet.Http
命名空间(所属Microsoft.AspNet.Http.Extensions.dll
中)下,为我们添加了几个扩展方法,分别用于设置和保存byte[]
类型、int
类型、以及string
类型,代码如下:
public static byte[] Get(this ISessionCollection session, string key); public static int? GetInt(this ISessionCollection session, string key); public static string GetString(this ISessionCollection session, string key); public static void Set(this ISessionCollection session, string key, byte[] value); public static void SetInt(this ISessionCollection session, string key, int value); public static void SetString(this ISessionCollection session, string key, string value);
所以,在Controller
里引用Microsoft.AspNet.Http
命名空间以后,我们就可以通过如下代码进行Session的设置和获取了:
Context.Session.SetString("Name", "Mike");
Context.Session.SetInt("Age", 21); ViewBag.Name = Context.Session.GetString("Name"); ViewBag.Age = Context.Session.GetInt("Age");
自定义类型的Session设置和获取
前面我们说了,要保存自定义类型的Session,需要将其类型转换成byte[]数组才行,在本例中,我们对bool类型的Session数据进行设置和获取的代码,示例如下:
public static class SessionExtensions { public static bool? GetBoolean(this ISessionCollection session, string key) { var data = session.Get(key); if (data == null) { return null; } return BitConverter.ToBoolean(data, 0); } public static void SetBoolean(this ISessionCollection session, string key, bool value) { session.Set(key, BitConverter.GetBytes(value)); } }
定义bool类型的扩展方法以后,我们就可以像SetInt/GetInt那样进行使用了,示例如下:
Context.Session.SetBoolean("Liar", true);
ViewBag.Liar = Context.Session.GetBoolean("Liar");
另外,ISessionCollection接口上还提供了Remove(string key)和Clear()两个方法分别用于删除某个Session值和清空所有的Session值的功能。但同时也需要注意,该接口并没提供之前版本中的Abandon方法功能。
基于Redis的Session管理
使用分布式Session,其主要工作就是将Session保存的地方从原来的内存换到分布式存储上,本节,我们以Redis存储为例来讲解分布式Session的处理。
先查看使用分布式Session的扩展方法,示例如下,我们可以看到,其Session容器需要是一个支持IDistributedCache
的接口示例。
public static IApplicationBuilder UseDistributedSession([NotNullAttribute]this IApplicationBuilder app, IDistributedCache cache, Action<SessionOptions> configure = null);
该接口是缓存Caching的通用接口,也就是说,只要我们实现了缓存接口,就可以将其用于Session的管理。进一步查看该接口发现,该接口中定义的Set方法还需要实现一个ICacheContext类型的缓存上下文(以便在调用的时候让其它程序进行委托调用),接口定义分别如下:
public interface IDistributedCache
{
void Connect(); void Refresh(string key); void Remove(string key); Stream Set(string key, object state, Action<ICacheContext> create); bool TryGetValue(string key, out Stream value); } public interface ICacheContext { Stream Data { get; } string Key { get; } object State { get; } void SetAbsoluteExpiration(TimeSpan relative); void SetAbsoluteExpiration(DateTimeOffset absolute); void SetSlidingExpiration(TimeSpan offset); }
接下来,我们基于Redis来实现上述功能,创建RedisCache
类,并继承IDistributedCache
,引用StackExchange.Redis
程序集,然后实现IDistributedCache
接口的所有方法和属性,代码如下:
using Microsoft.Framework.Cache.Distributed;
using Microsoft.Framework.OptionsModel;
using StackExchange.Redis;
using System; using System.IO; namespace Microsoft.Framework.Caching.Redis { public class RedisCache : IDistributedCache { // KEYS[1] = = key // ARGV[1] = absolute-expiration - ticks as long (-1 for none) // ARGV[2] = sliding-expiration - ticks as long (-1 for none) // ARGV[3] = relative-expiration (long, in seconds, -1 for none) - Min(absolute-expiration - Now, sliding-expiration) // ARGV[4] = data - byte[] // this order should not change LUA script depends on it private const string SetScript = (@" redis.call('HMSET', KEYS[1], 'absexp', ARGV[1], 'sldexp', ARGV[2], 'data', ARGV[4]) if ARGV[3] ~= '-1' then redis.call('EXPIRE', KEYS[1], ARGV[3]) end return 1"); private const string AbsoluteExpirationKey = "absexp"; private const string SlidingExpirationKey = "sldexp"; private const string DataKey = "data"; private const long NotPresent = -1; private ConnectionMultiplexer _connection; private IDatabase _cache; private readonly RedisCacheOptions _options; private readonly string _instance; public RedisCache(IOptions<RedisCacheOptions> optionsAccessor) { _options = optionsAccessor.Options; // This allows partitioning a single backend cache for use with multiple apps/services. _instance = _options.InstanceName ?? string.Empty; } public void Connect() { if (_connection == null) { _connection = ConnectionMultiplexer.Connect(_options.Configuration); _cache = _connection.GetDatabase(); } } public Stream Set(string key, object state, Action<ICacheContext> create) { Connect(); var context = new CacheContext(key) { State = state }; create(context); var value = context.GetBytes(); var result = _cache.ScriptEvaluate(SetScript, new RedisKey[] { _instance + key }, new RedisValue[] { context.AbsoluteExpiration?.Ticks ?? NotPresent, context.SlidingExpiration?.Ticks ?? NotPresent, context.GetExpirationInSeconds() ?? NotPresent, value }); // TODO: Error handling return new MemoryStream(value, writable: false); } public bool TryGetValue(string key, out Stream value) { value = GetAndRefresh(key, getData: true); return value != null; } public void Refresh(string key) { var ignored = GetAndRefresh(key, getData: false); } private Stream GetAndRefresh(string key, bool getData) { Connect(); // This also resets the LRU status as desired. // TODO: Can this be done in one operation on the server side? Probably, the trick would just be the DateTimeOffset math. RedisValue[] results; if (getData) { results = _cache.HashMemberGet(_instance + key, AbsoluteExpirationKey, SlidingExpirationKey, DataKey); } else { results = _cache.HashMemberGet(_instance + key, AbsoluteExpirationKey, SlidingExpirationKey); } // TODO: Error handling if (results.Length >= 2) { // Note we always get back two results, even if they are all null. // These operations will no-op in the null scenario. DateTimeOffset? absExpr; TimeSpan? sldExpr; MapMetadata(results, out absExpr, out sldExpr); Refresh(key, absExpr, sldExpr); } if (results.Length >= 3 && results[2].HasValue) { return new MemoryStream(results[2], writable: false); } return null; } private void MapMetadata(RedisValue[] results, out DateTimeOffset? absoluteExpiration, out TimeSpan? slidingExpiration) { absoluteExpiration = null; slidingExpiration = null; var absoluteExpirationTicks = (long?)results[0]; if (absoluteExpirationTicks.HasValue && absoluteExpirationTicks.Value != NotPresent) { absoluteExpiration = new DateTimeOffset(absoluteExpirationTicks.Value, TimeSpan.Zero); } var slidingExpirationTicks = (long?)results[1]; if (slidingExpirationTicks.HasValue && slidingExpirationTicks.Value != NotPresent) { slidingExpiration = new TimeSpan(slidingExpirationTicks.Value); } } private void Refresh(string key, DateTimeOffset? absExpr, TimeSpan? sldExpr) { // Note Refresh has no effect if there is just an absolute expiration (or neither). TimeSpan? expr = null; if (sldExpr.HasValue) { if (absExpr.HasValue) { var relExpr = absExpr.Value - DateTimeOffset.Now; expr = relExpr <= sldExpr.Value ? relExpr : sldExpr; } else { expr = sldExpr; } _cache.KeyExpire(_instance + key, expr); // TODO: Error handling } } public void Remove(string key) { Connect(); _cache.KeyDelete(_instance + key); // TODO: Error handling } } }
在上述代码中,我们使用了自定义类RedisCacheOptions
作为Redis的配置信息类,为了实现基于POCO的配置定义,我们还继承了IOptions
接口,该类的定义如下:
public class RedisCacheOptions : IOptions<RedisCacheOptions> { public string Configuration { get; set; } public string InstanceName { get; set; } RedisCacheOptions IOptions<RedisCacheOptions>.Options { get { return this; } } RedisCacheOptions IOptions<RedisCacheOptions>.GetNamedOptions(string name) { return this; } }
第三部,定义委托调用时使用的缓存上下文类CacheContext
,具体代码如下:
using Microsoft.Framework.Cache.Distributed;
using System;
using System.IO;
namespace Microsoft.Framework.Caching.Redis { internal class CacheContext : ICacheContext { private readonly MemoryStream _data = new MemoryStream(); internal CacheContext(string key) { Key = key; CreationTime = DateTimeOffset.UtcNow; } /// <summary> /// The key identifying this entry. /// </summary> public string Key { get; internal set; } /// <summary> /// The state passed into Set. This can be used to avoid closures. /// </summary> public object State { get; internal set; } public Stream Data { get { return _data; } } internal DateTimeOffset CreationTime { get; set; } // 可以让委托设置创建时间 internal DateTimeOffset? AbsoluteExpiration { get; private set; } internal TimeSpan? SlidingExpiration { get; private set; } public void SetAbsoluteExpiration(TimeSpan relative) // 可以让委托设置相对过期时间 { if (relative <= TimeSpan.Zero) { throw new ArgumentOutOfRangeException("relative", relative, "The relative expiration value must be positive."); } AbsoluteExpiration = CreationTime + relative; } public void SetAbsoluteExpiration(DateTimeOffset absolute) // 可以让委托设置绝对过期时间 { if (absolute <= CreationTime) { throw new ArgumentOutOfRangeException("absolute", absolute, "The absolute expiration value must be in the future."); } AbsoluteExpiration = absolute.ToUniversalTime(); } public void SetSlidingExpiration(TimeSpan offset) // 可以让委托设置offset过期时间 { if (offset <= TimeSpan.Zero) { throw new ArgumentOutOfRangeException("offset", offset, "The sliding expiration value must be positive."); } SlidingExpiration = offset; } internal long? GetExpirationInSeconds() { if (AbsoluteExpiration.HasValue && SlidingExpiration.HasValue) { return (long)Math.Min((AbsoluteExpiration.Value - CreationTime).TotalSeconds, SlidingExpiration.Value.TotalSeconds); } else if (AbsoluteExpiration.HasValue) { return (long)(AbsoluteExpiration.Value - CreationTime).TotalSeconds; } else if (SlidingExpiration.HasValue) { return (long)SlidingExpiration.Value.TotalSeconds; } return null; } internal byte[] GetBytes() { return _data.ToArray(); } } }
最后一步定义,RedisCache
中需要的根据key键获取缓存值的快捷方法,代码如下:
using StackExchange.Redis;
using System;
namespace Microsoft.Framework.Caching.Redis { internal static class RedisExtensions { private const string HmGetScript = (@"return redis.call('HMGET', KEYS[1], unpack(ARGV))"); internal static RedisValue[] HashMemberGet(this IDatabase cache, string key, params string[] members) { var redisMembers = new RedisValue[members.Length]; for (int i = 0; i < members.Length; i++) { redisMembers[i] = (RedisValue)members[i]; } var result = cache.ScriptEvaluate(HmGetScript, new RedisKey[] { key }, redisMembers); // TODO: Error checking? return (RedisValue[])result; } } }
至此,所有的工作就完成了,将该缓存实现注册为Session的provider的代码方法如下:
app.UseDistributedSession(new RedisCache(new RedisCacheOptions()
{
Configuration = "此处填写 redis的地址",
InstanceName = "此处填写自定义实例名" }), options => { options.CookieHttpOnly = true; });
参考:http://www.mikesdotnetting.com/article/270/sessions-in-asp-net-5
关于Caching
默认情况下,本地缓存使用的是IMemoryCache接口的示例,可以通过获取该接口的示例来对本地缓存进行操作,示例代码如下:
var cache = app.ApplicationServices.GetRequiredService<IMemoryCache>();
var obj1 = cache.Get("key1");
bool obj2 = cache.Get<bool>("key2");
对于,分布式缓存,由于AddCaching,默认将IMemoryCache实例作为分布式缓存的provider了,代码如下:
public static class CachingServicesExtensions { public static IServiceCollection AddCaching(this IServiceCollection collection) { collection.AddOptions(); return collection.AddTransient<IDistributedCache, LocalCache>() .AddSingleton<IMemoryCache, MemoryCache>(); } }
所以,要使用新的分布式Caching实现,我们需要注册自己的实现,代码如下:
services.AddTransient<IDistributedCache, RedisCache>();
services.Configure<RedisCacheOptions>(opt =>
{
opt.Configuration = "此处填写 redis的地址";
opt.InstanceName = "此处填写自定义实例名";
});
基本的使用方法如下:
var cache = app.ApplicationServices.GetRequiredService<IDistributedCache>();
cache.Connect();
var obj1 = cache.Get("key1"); //该对象是流,需要将其转换为强类型,或自己再编写扩展方法 var bytes = obj1.ReadAllBytes();
同步与推荐
本文已同步至目录索引:解读ASP.NET 5 & MVC6系列