利用AOP实现SqlSugar自动事务

时间：2022-06-29 07:46:05 编辑：袖梨来源：一聚教程网

本文实例为大家分享了如何利用AOP实现SqlSugar自动事务，供大家参考，具体内容如下

先看一下效果,带接口层的三层架构:

BL层：

 public class StudentBL : IStudentService
   {
     private ILogger mLogger;
     private readonly IStudentDA mStudentDa;
     private readonly IValueService mValueService;

     public StudentService(IStudentDA studentDa,IValueService valueService)
     {
       mLogger = LogManager.GetCurrentClassLogger();
       mStudentDa = studentDa;
       mValueService = valueService;

     }

     [TransactionCallHandler]
     public IList GetStudentList(Hashtable paramsHash)
     {
       var list = mStudentDa.GetStudents(paramsHash);
       var value = mValueService.FindAll();
       return list;
     }
   }

假设GetStudentList方法里的mStudentDa.GetStudents和mValueService.FindAll不是查询操作，而是更新操作，当一个失败另一个需要回滚，就需要在同一个事务里，当一个出现异常就要回滚事务。

特性TransactionCallHandler就表明当前方法需要开启事务，并且当出现异常的时候回滚事务,方法执行完后提交事务。

DA层：

 public class StudentDA : IStudentDA
   {

     private SqlSugarClient db;
     public StudentDA()
     {
       db = SugarManager.GetInstance().SqlSugarClient;
     }
     public IList GetStudents(Hashtable paramsHash)
     {
       return db.Queryable().AS("T_Student").With(SqlWith.NoLock).ToList();
     }
   }

对SqlSugar做一下包装

 public class SugarManager
   {
     private static ConcurrentDictionary _cache =
       new ConcurrentDictionary();
     private static ThreadLocal _threadLocal;
     private static readonly string _connStr = @"Data Source=localhost;port=3306;Initial Catalog=thy;user id=root;password=xxxxxx;Charset=utf8";
     static SugarManager()
     {
       _threadLocal = new ThreadLocal();
     }

     private static SqlSugarClient CreatInstance()
     {
       SqlSugarClient client = new SqlSugarClient(new ConnectionConfig()
       {
         ConnectionString = _connStr, //必填
         DbType = DbType.MySql, //必填
         IsAutoCloseConnection = true, //默认false
         InitKeyType = InitKeyType.SystemTable
       });
       var key=Guid.NewGuid().ToString().Replace("-", "");
       if (!_cache.ContainsKey(key))
       {
         _cache.TryAdd(key,new SqlClient(client));
         _threadLocal.Value = key;
         return client;
       }
       throw new Exception("创建SqlSugarClient失败");
     }
     public static SqlClient GetInstance()
     {
       var id= _threadLocal.Value;
       if (string.IsNullOrEmpty(id)||!_cache.ContainsKey(id))
         return new SqlClient(CreatInstance());
       return _cache[id];
     }


     public static void Release()
     {
       try
       {
         var id = GetId();
         if (!_cache.ContainsKey(id))
           return;
         Remove(id);
       }
       catch (Exception e)
       {
         throw e;
       }
     }
     private static bool Remove(string id)
     {
       if (!_cache.ContainsKey(id)) return false;

       SqlClient client;

       int index = 0;
       bool result = false;
       while (!(result = _cache.TryRemove(id, out client)))
       {
         index++;
         Thread.Sleep(20);
         if (index > 3) break;
       }
       return result;
     }
     private static string GetId()
     {
       var id = _threadLocal.Value;
       if (string.IsNullOrEmpty(id))
       {
         throw new Exception("内部错误: SqlSugarClient已丢失.");
       }
       return id;
     }

     public static void BeginTran()
     {
       var instance=GetInstance();
       //开启事务
       if (!instance.IsBeginTran)
       {
         instance.SqlSugarClient.Ado.BeginTran();
         instance.IsBeginTran = true;
       }
     }

     public static void CommitTran()
     {
       var id = GetId();
       if (!_cache.ContainsKey(id))
         throw new Exception("内部错误: SqlSugarClient已丢失.");
       if (_cache[id].TranCount == 0)
       {
         _cache[id].SqlSugarClient.Ado.CommitTran();
         _cache[id].IsBeginTran = false;
       }
     }

     public static void RollbackTran()
     {
       var id = GetId();
       if (!_cache.ContainsKey(id))
         throw new Exception("内部错误: SqlSugarClient已丢失.");
       _cache[id].SqlSugarClient.Ado.RollbackTran();
       _cache[id].IsBeginTran = false;
       _cache[id].TranCount = 0;
     }

     public static void TranCountAddOne()
     {
       var id = GetId();
       if (!_cache.ContainsKey(id))
         throw new Exception("内部错误: SqlSugarClient已丢失.");
       _cache[id].TranCount++;
     }
     public static void TranCountMunisOne()
     {
       var id = GetId();
       if (!_cache.ContainsKey(id))
         throw new Exception("内部错误: SqlSugarClient已丢失.");
       _cache[id].TranCount--;
     }
   }

_cache保存SqlSugar实例，_threadLocal确保同一线程下取出的是同一个SqlSugar实例。

不知道SqlSugar判断当前实例是否已经开启事务，所以又将SqlSugar包了一层。

 public class SqlClient
   {
     public SqlSugarClient SqlSugarClient;
     public bool IsBeginTran = false;
     public int TranCount = 0;

     public SqlClient(SqlSugarClient sqlSugarClient)
     {
       this.SqlSugarClient = sqlSugarClient;
     }
   }

IsBeginTran标识当前SqlSugar实例是否已经开启事务，TranCount是一个避免事务嵌套的计数器。

一开始的例子

 [TransactionCallHandler]
      public IList GetStudentList(Hashtable paramsHash)
      {
        var list = mStudentDa.GetStudents(paramsHash);
        var value = mValueService.FindAll();
        return list;
      }

TransactionCallHandler表明该方法要开启事务，但是如果mValueService.FindAll也标识了TransactionCallHandler,又要开启一次事务？所以用TranCount做一个计数。

使用Castle.DynamicProxy

要实现标识了TransactionCallHandler的方法实现自动事务，使用Castle.DynamicProxy实现BL类的代理

Castle.DynamicProxy一般操作

 public class MyClass : IMyClass
  {
    public void MyMethod()
    {
      Console.WriteLine("My Mehod");
    }
 }
 public class TestIntercept : IInterceptor
   {
     public void Intercept(IInvocation invocation)
     {
       Console.WriteLine("before");
       invocation.Proceed();
       Console.WriteLine("after");
     }
   }

  var proxyGenerate = new ProxyGenerator();
  TestIntercept t=new TestIntercept();
  var pg = proxyGenerate.CreateClassProxy(t);
  pg.MyMethod();
  //输出是
  //before
  //My Mehod
  //after

before就是要开启事务的地方，after就是提交事务的地方

最后实现

 public class TransactionInterceptor : IInterceptor
   {
     private readonly ILogger logger;
     public TransactionInterceptor()
     {
       logger = LogManager.GetCurrentClassLogger();
     }
     public void Intercept(IInvocation invocation)
     {
       MethodInfo methodInfo = invocation.MethodInvocationTarget;
       if (methodInfo == null)
       {
         methodInfo = invocation.Method;
       }

       TransactionCallHandlerAttribute transaction =
         methodInfo.GetCustomAttributes(true).FirstOrDefault();
       if (transaction != null)
       {
         SugarManager.BeginTran();
         try
         {
           SugarManager.TranCountAddOne();
           invocation.Proceed();
           SugarManager.TranCountMunisOne();
           SugarManager.CommitTran();
         }
         catch (Exception e)
         {
           SugarManager.RollbackTran();
           logger.Error(e);
           throw e;
         }

       }
       else
       {
         invocation.Proceed();
       }
     }
   }
   [AttributeUsage(AttributeTargets.Method, Inherited = true)]
   public class TransactionCallHandlerAttribute : Attribute
   {
     public TransactionCallHandlerAttribute()
     {

     }
   }

Autofac与Castle.DynamicProxy结合使用

创建代理的时候一个BL类就要一次操作

 proxyGenerate.CreateClassProxy(t);

而且项目里BL类的实例化是交给IOC容器控制的，我用的是Autofac。当然Autofac和Castle.DynamicProxy是可以结合使用的

using System.Reflection;
using Autofac;
using Autofac.Extras.DynamicProxy;
using Module = Autofac.Module;
public class BusinessModule : Module
  {
    protected override void Load(ContainerBuilder builder)
    {
      var business = Assembly.Load("FTY.Business");
      builder.RegisterAssemblyTypes(business)
        .AsImplementedInterfaces().InterceptedBy(typeof(TransactionInterceptor)).EnableInterfaceInterceptors();
      builder.RegisterType();
    }
  }

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