Attribute In Member Field

可绑定到成员变量的Attribute。

可绑定到成员变量上的Attribute
 1using System;
 2using System.Reflection;
 3using System.ComponentModel;
 4
 5namespace Relaction.Attribute_in_member_field
 6{
 7    public interface IFieldShow
 8    {
 9        string Show(object o);
10    }
11    /**//// <summary>
12    /// 可用于字段或属性的自定义属性。
13    /// </summary>
14    /// 
15    [AttributeUsage(AttributeTargets.Field|AttributeTargets.Property,Inherited = false,AllowMultiple=false)]
16    public class FieldShowAttribute:Attribute
17    {
18        private bool _show = false;
19        private Type _showclass = null;
20        public bool Show
21        {
22            get
23            {
24                return _show;
25            }
26        }
27        public Type ShowClass
28        {
29            get 
30            {
31                return _showclass;
32            }
33        }
34        public FieldShowAttribute(bool show,Type showclass)
35        {
36            _show = show;
37            _showclass = showclass;
38            if(_showclass == null)
39            {
40                throw(new Exception("出错！"));
41            }
42        }
43        public IFieldShow CreateShowInstance()
44        {
45            object o ;
46            ConstructorInfo cinfo = _showclass.GetConstructor(new Type[]{});
47            o = cinfo.Invoke(null);
48            return (IFieldShow)o;
49        }
50    }
51}

测试上面的属性：

测试上面的属性
 1using System;
 2
 3namespace Relaction.Attribute_in_member_field
 4{
 5    /**//// <summary>
 6    /// 测试字段和属性的自定义属性晕，
 7    /// </summary>
 8    public class StringFieldShow:IFieldShow
 9    {
10        public StringFieldShow()
11        {
12        }
13        IFieldShow 成员#region IFieldShow 成员
14
15        public string Show(object o)
16        {
17            return o.ToString();
18        }
19
20        #endregion
21    }
22    public class AttrFieldTest
23    {
24        [FieldShow(true,typeof(StringFieldShow))]
25        public int _num = 0;
26
27        public AttrFieldTest()
28        {
29        }
30    }
31}

测试：

测试
 1    private void button3_Click(object sender, System.EventArgs e)
 2        {
 3            AttrFieldTest[] o = new AttrFieldTest[]{new AttrFieldTest(),new AttrFieldTest()};
 4            o[0]._num = 15;
 5            o[1]._num = 30;
 6            foreach(AttrFieldTest item in o)
 7            {
 8                foreach(FieldInfo field in item.GetType().GetFields())
 9                {
10                  FieldShowAttribute[] fattr = (FieldShowAttribute[])field.GetCustomAttributes(typeof(FieldShowAttribute),false);
11                    if(fattr.Length != 0)
12                    {
13                        label1.Text += field.Name+fattr[0].CreateShowInstance().Show(field.GetValue(item));
14                    }
15                }
16            }
17        }

不是很理解。呵呵
也可以用表态的：

修改后的FieldShowAttribute
 1using System;
 2using System.Reflection;
 3using System.ComponentModel;
 4
 5namespace Relaction.Attribute_in_member_field
 6{
 7    public interface IFieldShow
 8    {
 9        string Show(object o);
10    }
11    /**//// <summary>
12    /// 可用于字段或属性的自定义属性。
13    /// </summary>
14    /// 
15    [AttributeUsage(AttributeTargets.Field|AttributeTargets.Property,Inherited = false,AllowMultiple=false)]
16    public class FieldShowAttribute:Attribute
17    {
18        public FieldShowAttribute(bool show,Type showclass)
19        {
20            _show = show;
21            _showclass = showclass;
22            if(_showclass == null)
23            {
24                throw(new Exception("出错！"));
25            }
26        }
27
28
29        public bool Show
30        {
31            get
32            {
33                return _show;
34            }
35        }private bool _show = false;
36
37        public Type ShowClass
38        {
39            get 
40            {
41                return _showclass;
42            }
43        }private Type _showclass = null;
44    
45        public IFieldShow CreateShowInstance()
46        {
47            object o ;
48            ConstructorInfo cinfo = _showclass.GetConstructor(new Type[]{});
49            o = cinfo.Invoke(null);
50            return (IFieldShow)o;
51        }
52        public static string ShowValue(FieldShowAttribute attr,object o,FieldInfo valueobject)
53        {
54            MethodInfo mi = attr.ShowClass.GetMethod("Show",BindingFlags.Static|BindingFlags.Public);
55            return (string)mi.Invoke(null,new object[]{valueobject.GetValue(o)});
56        }
57    }
58}
59

修改后贴上FieldShowAttribute类
 1using System;
 2
 3namespace Relaction.Attribute_in_member_field
 4{
 5    /**//// <summary>
 6    /// 测试字段和属性的自定义属性
 7    /// </summary>
 8    public class StringFieldShow:IFieldShow
 9    {
10        public StringFieldShow()
11        {
12        }
13        IFieldShow 成员#region IFieldShow 成员
14
15        public string Show(object o)
16        {
17            return o.ToString();
18        }
19
20        #endregion
21    }
22    public class StringFieldShow2
23    {
24        public static string Show(object o)
25        {
26            return o.ToString();
27        }
28    }
29    public class AttrFieldTest
30    {
31        [FieldShow(true,typeof(StringFieldShow2))]
32        public int _num = 0;
33
34        public AttrFieldTest()
35        {
36        }
37    }
38}
39

客户调用
 1    private void button4_Click(object sender, System.EventArgs e)
 2        {
 3            AttrFieldTest[] o = new AttrFieldTest[]{new AttrFieldTest(),new AttrFieldTest()};
 4            o[0]._num = 15;
 5            o[1]._num = 30;
 6            foreach(AttrFieldTest item in o)
 7            {
 8                foreach(FieldInfo field in item.GetType().GetFields())
 9                {
10                    FieldShowAttribute[] fattr = (FieldShowAttribute[])field.GetCustomAttributes(typeof(FieldShowAttribute),false);
11                    if(fattr.Length != 0)
12                    {
13                        label1.Text += FieldShowAttribute.ShowValue(fattr[0],item,field);
14                    }
15                }
16            }
17        }