数据绑定组件实现

       在实际开发过程中需要经常编写Entity和UI数据交换相关代码，虽然代码并不复杂但确是一个非常烦琐的事情。为了解决这一问题所以编写一个数据绑定组件来处理这方面的事情，即减少代码编写的时也提高代码维护的方便性。

       组件类结构图：

      

 

组件主要有三个对象

       EntityDataBinder

              数据绑定对象，要用于Entity数据输出UI和UI导入数据给Entity。

       IPropertyMapper

成员映射描述，用于表示Entity的某个数据成员对应着相关对象的成员属性；对象的Changer属性用于描述数据输入和输入的转换方式。

       IChanger

数据转换对象，用于隔离数据输入和输出转换的实现，可以方便开发人员实现自己的转换类型方式。组件实现了基础的转换对象Changer、ToStringFormat和DateTimeToString等。

      

       相关实现代码

       EntityDataBinder：

       public class EntityDataBinder<T> where T:new()

    {

        List<IPropertyMapper<T>> mMappers = new List<IPropertyMapper<T>>();

        public void AddMapper(IPropertyMapper<T> item)

        {

           

            mMappers.Add(item);

        }

        public void Import(T entity)

        {

            foreach (IPropertyMapper<T> item in mMappers)

            {

                item.Import(entity);

            }

        }

        public T Import()

        {

            T entity = new T();

            Import(entity);

            return entity;

        }

        public void Export(T entity)

        {

            foreach (IPropertyMapper<T> item in mMappers)

            {

                item.Export(entity);

            }

        }

        public void AddMapper(object source, string sourceproperty, string entityproperty)

        {

            AddMapper(source, sourceproperty, entityproperty, null);

        }

        public void AddMapper(object source, string sourceproperty, string entityproperty,IChanger changer)

        {

            IPropertyMapper<T> mapper;

            if (changer == null)

            {

                mapper = new PropertyMapper<T>(source, GetSProperty(source, sourceproperty), GetEProperty(entityproperty));

               

            }

            else

            {

                mapper = new PropertyMapper<T>(source, GetSProperty(source, sourceproperty), GetEProperty(entityproperty),changer);

            }

            AddMapper(mapper);

        }

     ….

     }

 

       PropertyMapper

public class PropertyMapper<T> : IPropertyMapper<T>

    {

        public PropertyMapper(object source, PropertyInfo sourceproperty, PropertyInfo entityproperty)

        {

            Source = source;

            SourceProperty = sourceproperty;

            EntityProperty = entityproperty;

        }

        public PropertyMapper(object source, PropertyInfo sourceproperty, PropertyInfo entityproperty, IChanger changer)

        {

            Source = source;

            SourceProperty = sourceproperty;

            EntityProperty = entityproperty;

            Changer = changer;

        }

        #region IPropertyMapper 成员

 

        public void Import(T entity)

        {

            OnImport(entity);

        }

        public void Export(T entity)

        {

            OnExport(entity);

        }

 

      

        protected virtual void OnExport(T entity)

        {

            object value = EntityProperty.GetValue(entity, null);

            if (value == null)

                return;

             object newvalue = Changer.Export(value);

            try

            {

                SourceProperty.SetValue(Source, newvalue, null);

               

            }

            catch (Exception e)

            {

                string err = string.Format(

                    ErrorMsg.VALUE_CAST, entity.GetType(), EntityProperty, Source.GetType(), SourceProperty);

                throw (new SwitchException(err, e));

            }

           

        }

        protected virtual void OnImport(T entity)

        {

            object value = SourceProperty.GetValue(Source,null);

             object newvalue = Changer.Import(value);

            try

            {

                EntityProperty.SetValue(entity,newvalue, null);

            }

            catch (Exception e)

            {

                string err = string.Format(

                   ErrorMsg.VALUE_CAST,Source.GetType(), mSourceProperty, entity.GetType(), mEntityProperty);

                throw (new SwitchException(err, e));

            }

          

        }

            ….

      }

      

IChanger：

    public interface IChanger

    {

        object Export(object value);

        object Import(object value);

    }

    public class Changer:IChanger

    {

        #region IChanger 成员

 

        public virtual object Export(object value)

        {

            return value;

        }

 

        public virtual object Import(object value)

        {

            return value;

        }

 

        #endregion

    }

    public abstract class ToStringFormat : Changer

    {

        public ToStringFormat()

        {

        }

        public ToStringFormat(string format)

        {

            Format = format;

        }

        private string mFormat = "{0}";

        public string Format

        {

            get

            {

                return mFormat;

            }

            set

            {

                mFormat = value;

            }

        }

        public override object Export(object value)

        {

            return string.Format(mFormat, value);

        }

    }

 

使用例程：

            mEmployeeBinder = new HFSoft.DataSwitch.EntityDataBinder<Employees>();

          mEmployeeBinder .AddMapper(textBox1, "Text", "FirstName");

          mEmployeeBinder .AddMapper(textBox2, "Text", "LastName");

          mEmployeeBinder .AddMapper(dateTimePicker1, "Value", "BirthDate");

         //获取数据输入

              Employees emp = mEmployeeBinder.Import();

 

       组件刚刚编写完成和简单应用测试，功能还很简陋；由于数据交换过程采用反射所以性能并不理想。