创建上下文对象

///

/// 负责创建EF上下文对象，保证线程内唯一，在一次请求内，只创建一次该对象
///

public class DbContextFactory
{

public static DbContext GetCurrentDbContext()
{
DbContext dbContext = (DbContext)CallContext.GetData("dbContext");
if(dbContext==null)
{
dbContext = new book_shopEntities();
CallContext.SetData("dbContext", dbContext);
}
return dbContext;
}
}