44 lines
1.8 KiB
C#
44 lines
1.8 KiB
C#
using CC.Yi.Model;
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using Microsoft.EntityFrameworkCore;
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using System.Collections.Concurrent;
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using System.Threading;
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namespace CC.Yi.DAL
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{
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public class DbContentFactory
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{
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private static DataContext Webcontext;
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public static void Initialize(DataContext webContext)
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{
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Webcontext = webContext;
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}
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public static DataContext GetCurrentDbContent()
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{
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//return new DataModelContainer();
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//一次请求共用一个上下文实例
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//每一次http请求都会开启一个新的线程，保证在一个线程中,DbContext是唯一的
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//CallContext：是线程内部唯一的数据槽（一块内存空间/容器）,相当于一个键值对数据容器，通过key获取value了,需要引入System.Runtime.Remoting.Messaging;命名空间
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DataContext db = CallContext.GetData("DbContext") as DataContext;
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//从 CallContext 中检索具有指定key“DbContext”的对象，并强转为DbContext
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if (db == null)//线程在数据槽里面没有此上下文
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{
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db = Webcontext;
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CallContext.SetData("DbContext", db);//放到数据槽中去,DbContext是key，db是value
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}
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return db;
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}
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private static class CallContext
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{
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static ConcurrentDictionary<string, AsyncLocal<object>> state = new ConcurrentDictionary<string, AsyncLocal<object>>();
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public static void SetData(string name, object data) =>
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state.GetOrAdd(name, _ => new AsyncLocal<object>()).Value = data;
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public static object GetData(string name) =>
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state.TryGetValue(name, out AsyncLocal<object> data) ? data.Value : null;
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}
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}
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}
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