EF、Repository、Factory、Service间关系
- 实体（Entities）：具备唯一ID，能够被持久化，具备业务逻辑，对应现实世界业务对象。
- 值对象（Value objects）：不具有唯一ID，由对象的属性描述，一般为内存中的临时对象，可以用来传递参数或对实体进行补充描述。
- 工厂（Factories）：主要用来创建实体，目前架构实践中一般采用IOC容器来实现工厂的功能。
- 仓库（Repositories）：用来管理实体的集合，封装持久化框架。
- 服务（Services）：为上层建筑提供可操作的接口，负责对领域对象进行调度和封装，同时可以对外提供各种形式的服务。
1.定义Context：
2.定义Context对应的Factory
通用DatabaseFactory的定义：利用反射生成Factory的实例。
get()方法返回Factory实例与Context的绑定关系。如果Context已经存在，不再重新new一个entity，使用已有entity，用于防止方法嵌套，导致两个entity不同
public class DatabaseFactoryBase<T> : IDatabaseFactory<T> where T:DbContext,IDisposable,new()
{
private T _dataContext;
//protected Boolean _objectDisposed;
protected static Func<Boolean> _funcNeedCreateInstance = null;
protected static Boolean DefaultFuncChecked = false;
protected static void CreateDefaultChecker()
{
Type tdf = typeof(IDatabaseFactory<T>);
var targetAssembly = AppDomain.CurrentDomain.GetAssemblies().Where(e => e.IsDynamic == false && e.GlobalAssemblyCache == false
&& e.FullName.Contains("NewCRM.Common")).FirstOrDefault();
if (targetAssembly == null) return;
var factoryTypeName = "NewCRM.Common.DependencyInjection.IocFactory";
var factoryType = targetAssembly.GetType(factoryTypeName);
if (factoryType!=null)
{
var instanceProp = factoryType.GetProperty("Instance", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static);
if (instanceProp!=null)
{
var method = instanceProp.PropertyType.GetMethod("GetRegistration", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);
if (method != null)
{
var returnType = method.ReturnType;
var lsPropType = returnType.GetProperty("LifeStyle", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance).PropertyType;
var peRegistration = Expression.Variable(returnType);
var boolType = typeof(Boolean);
var peResult = Expression.Variable(boolType);
var listFullExpression = new List<Expression>();
var expInitResult = Expression.Assign(peResult, Expression.Constant(false));
listFullExpression.Add(expInitResult);
var instance = instanceProp.GetValue(null);
var expGetRegistration = Expression.Assign(peRegistration, Expression.Call(Expression.Constant(instance), method,Expression.Constant(tdf)));
listFullExpression.Add(expGetRegistration);
var checkLifeStyle = Expression.OrElse(
Expression.Equal(peRegistration, Expression.Constant(null)),
Expression.Equal(Expression.Convert(Expression.Property(peRegistration, "LifeStyle"),typeof(Int32)), Expression.Constant(2))
);
var expAssignResult = Expression.IfThen(checkLifeStyle,
Expression.Assign(peResult, Expression.Constant(true)));
listFullExpression.Add(expAssignResult);
var lbRet = Expression.Label(boolType);
listFullExpression.Add(
Expression.MakeGoto(
GotoExpressionKind.Return,
lbRet,
peResult,
boolType
)
);
listFullExpression.Add(
Expression.Label(lbRet, Expression.Default(boolType)));
var m2 = Expression.Lambda<Func<Boolean>>(
Expression.Block(new ParameterExpression[] { peRegistration, peResult }, listFullExpression)
);
var m3 = m2.Compile();
_funcNeedCreateInstance = m3;
}
}
}
}
public DatabaseFactoryBase()
{
//_objectDisposed = false;
}
/// <summary>
/// Dispose underlying resource
/// </summary>
public virtual void ReleaseCurrentContext()
{
try
{
if (_dataContext != null /*&& !_objectDisposed*/)
{
System.Diagnostics.Debug.WriteLine(String.Format("Database Factory:Release context {0}", typeof(T).FullName));
//_objectDisposed = true;
_dataContext.Dispose();
}
}
finally
{
_dataContext = null;
}
}
/// <summary>
/// Dispose underlying resource
/// </summary>
public virtual void Dispose()
{
ReleaseCurrentContext();
}
/// <summary>
/// Get the factory instance
/// </summary>
/// <returns>datacontext instance</returns>
public virtual IAutoDisposeDataContext<T> Get()
{
var needCreateInstance = NeedCreateInsance();
if ((!needCreateInstance || UnitTestHelper.UnitTestMode) && _dataContext != null) return new AutoDisposeDataContext<T>(_dataContext,this);
_dataContext = new T();
#if DEBUG
System.Diagnostics.Debug.WriteLine(String.Format("Database Factory:Creating context {0}", typeof(T).FullName));
#endif
return new AutoDisposeDataContext<T>(_dataContext,this);
}
public virtual bool NeedCreateInsance()
{
//Type tdf = typeof(IDatabaseFactory<T>);
//var instance = IocFactory.Instance;
//var impl = instance.GetRegistration(tdf);
//Boolean needCreateInstance = false;
////if the impl is null,it use the default factory
//if (impl == null || impl.LifeStyle == IocLifeStyle.Transient)
//{
// needCreateInstance = true;
//}
//return needCreateInstance;
if (!DefaultFuncChecked)
{
CreateDefaultChecker();
DefaultFuncChecked = true;
}
if (_funcNeedCreateInstance != null) return _funcNeedCreateInstance();
return true;
}
}
定义Context与Factory的绑定关系
public class AutoDisposeDataContext<T> : IAutoDisposeDataContext<T> where T : DbContext, new()
{
private T _dataContext;
private IDatabaseFactory<T> _databaseFactory;
public AutoDisposeDataContext(T dataContext, IDatabaseFactory<T> databaseFactory)
{
_dataContext = dataContext;
_databaseFactory = databaseFactory;
}
public T Context
{
get
{
return _dataContext;
}
}
public void Dispose()
{
Boolean useActualDb = false;
if (Context is DbContext)
{
var adapter = Context as IObjectContextAdapter;
if (adapter != null && adapter.ObjectContext != null) useActualDb = true;
}
if (_databaseFactory.NeedCreateInsance() && (useActualDb || !UnitTestHelper.UnitTestMode))
{
Context.Dispose();
_databaseFactory.ReleaseCurrentContext();
}
//Type tdf = typeof(IDatabaseFactory<T>);
//var instance = IocFactory.Instance;
//var impl = instance.GetRegistration(tdf);
////do not dispose object in unit test mode
//if ( (impl==null || impl.LifeStyle == IocLifeStyle.Transient) && !UnitTestHelper.UnitTestMode)
//{
// _databaseFactory.Dispose();
//}
}
}
3.每个context中的表对应的Respository的构造函数中，传入所在Context的Factory。
Context对应的RepositoryBase
公共RepositoryBase基类，以及其对factory的调用
目的：各表的Respository通过Factory实现对Context中对应表的增、删、改、查……基本操作。实现的增、删、改、查……基本操作的抽象
Respository：为Service提供服务，为其提供基本的操作。调用
Service：针对特定的业务逻辑，调用Respository来实现对数据库的操作
