C#拾贝

C#拾贝

C#C#技巧C#进阶

不积跬步无以至千里，不积小流无以成江河

C#拾贝

一、Linq

1、以...开头 StartsWith

1. Repeater1.DataSource=con.Users.Where(r=>r.Nickname.StartsWith("李")); 
   
   

   ---

2. Repeater1.DataBind(); 
   
   

   ---

2、以...结尾 EndsWith

1. Repeater1.DataSource=con.Users.Where(r=>r.Nickname.EndsWith("同")); 
   
   

   ---

2. Repeater1.DataBind(); 
   
   

   ---

3、模糊差(包含) Contains

1. Repeater1.DataSource=con.Users.Where(r=>r.Nickname.Contains("蘇")); 
   
   

   ---

2. Repeater1.DataBind(); 
   
   

   ---

4、个数 Count()或者Tolist().Count

1. Response.Write("总个数:"+con.Users.Count()); 
   
   

   ---

2. Response.Write("总个数:"+con.Users.Tolist().Count; 
   
   

   ---

5、最大值 Max(r=>r.列名)

1. Response.Write("总个数:"+con.Users.Tolist().Max(r=>r.Ids); 
   
   

   ---

6、最小值 Min(r=>r.列名)

1. Response.Write("总个数:"+con.Users.Tolist().Min(r=>r.Ids); 
   
   

   ---

7、平均值 Average(r=>r.列名)

1. Response.Write("总个数:"+con.Users.Tolist().Average(r=>r.Ids); 
   
   

   ---

8、求和 Sum(r=>r.列名)

1. Response.Write("总个数:"+con.Users.Tolist().Sum(r=>r.Ids); 
   
   

   ---

9、升序 OrderBy(r=>r.列名)

1. Repeater1.DataSource=con.Users.Tolist().OrderBy(r=>r.Ids); 
   
   

   ---

10、降序 OrderByDescending(r=>r.列名)

1. Repeater1.DataSource=con.Users.Tolist().OrderByDescending(r=>r.Ids); 
   
   

   ---

11、分页 Skip()--跳过多少条 Take()--每页取多少条

1. Repeater1.DataSource=con.Users.Tolist().Skip(0).Take(PageCount) 表示第一页跳过0条，每页取PageCount条 
   
   

   ---

二、模拟键盘按键

注

通过键盘按键可以调用一些软件的快捷键，比如录屏、截图、语言

键位对照表：https://docs.microsoft.com/en-us/windows/win32/inputdev/virtual-key-codes 十六进制转十进制即可

如虚拟键值 ESC键对应十六进制为0x1B十进制为27

---

键盘键与虚拟键码对照表

1. ---

2. [DllImport("user32.dll", EntryPoint = "keybd_event")] 
   
   

   ---

3. ---

4. public static extern void Keybd_event( 
   
   

   ---

5. ---

6. byte bvk,//虚拟键值 ESC键对应的是27 16进制为0x1B 
   
   

   ---

7. ---

8. byte bScan,//0 
   
   

   ---

9. ---

10. int dwFlags,//0为按下，1按住，2释放 
    
    

    ---

11. ---

12. int dwExtraInfo//0 
    
    

    ---

13. ---

14. ); 
    
    

    ---

15. ---

16. ---

17. ---

18. void Start() 
    
    

    ---

19. ---

20. { 
    
    

    ---

21. ---

22. Keybd_event(27,0,0,0); 
    
    

    ---

23. ---

24. Keybd_event(27, 0, 1, 0); 
    
    

    ---

25. ---

26. Keybd_event(27, 0, 2, 0); 
    
    

    ---

27. ---

28. } 
    
    

    ---

三、WPF另类投屏方案

有时希望WPF中可以将某些一个页面不同窗口投到不同的屏幕上去，类似仿真操控台上多个屏幕分别输出到不同的显示器。这时候可以通过窗口抓屏的方式，一秒抓30次来模拟录屏，在将抓的图替换到需要的窗口，不同屏幕放不同窗口。

API: RenderTargetBitmap

四、WPF白板实现

API:inkcanvas

DrawingAttributes 可以设置笔触大小、颜色、平滑等

ColorDialog 作为调色盘

PreviewMouseWheel 事件滚轮控制笔触大小

五、Attribute使用

1、为枚举添加描述

1. using System; 
   
   

   ---

2. using System.Collections.Generic; 
   
   

   ---

3. using System.ComponentModel; 
   
   

   ---

4. using System.Linq; 
   
   

   ---

5. using System.Reflection; 
   
   

   ---

6. using System.Text; 
   
   

   ---

7. using System.Threading.Tasks; 
   
   

   ---

8. ---

9. namespace demo 
   
   

   ---

10. { 
    
    

    ---

11. /// <summary> 
    
    

    ---

12. /// 枚举类 
    
    

    ---

13. /// </summary> 
    
    

    ---

14. public enum TypeEnum 
    
    

    ---

15. { 
    
    

    ---

16. [EnumText("活跃型")] 
    
    

    ---

17. Active = 1, 
    
    

    ---

18. ---

19. [EnumText("健康型")] 
    
    

    ---

20. Healthy = 2, 
    
    

    ---

21. ---

22. [EnumText("稳健型")] 
    
    

    ---

23. Steady = 3 
    
    

    ---

24. } 
    
    

    ---

25. /// <summary> 
    
    

    ---

26. /// 自定义Attribute 
    
    

    ---

27. /// </summary> 
    
    

    ---

28. public class EnumText : Attribute 
    
    

    ---

29. { 
    
    

    ---

30. public EnumText(String text) 
    
    

    ---

31. { 
    
    

    ---

32. this.Text = text; 
    
    

    ---

33. } 
    
    

    ---

34. ---

35. public String Text { get; set; } 
    
    

    ---

36. } 
    
    

    ---

37. /// <summary> 
    
    

    ---

38. /// 帮助类 
    
    

    ---

39. /// </summary> 
    
    

    ---

40. public class EnumHelper 
    
    

    ---

41. { 
    
    

    ---

42. /// <summary> 
    
    

    ---

43. /// 获取自定义attribute  
    
    

    ---

44. /// </summary> 
    
    

    ---

45. /// <typeparam name="T"></typeparam> 
    
    

    ---

46. /// <param name="enumObj"></param> 
    
    

    ---

47. /// <returns></returns> 
    
    

    ---

48. public static T GetAttribute<T>(Enum enumObj)where T:Attribute 
    
    

    ---

49. { 
    
    

    ---

50. Type type = enumObj.GetType(); 
    
    

    ---

51. Attribute attr = null; 
    
    

    ---

52. try 
    
    

    ---

53. { 
    
    

    ---

54. String enumName = Enum.GetName(type, enumObj); //获取对应的枚举名 
    
    

    ---

55. FieldInfo field = type.GetField(enumName);  
    
    

    ---

56. attr = field.GetCustomAttribute(typeof(T), false); 
    
    

    ---

57. } 
    
    

    ---

58. catch (Exception ex) 
    
    

    ---

59. { 
    
    

    ---

60. Console.WriteLine(ex); 
    
    

    ---

61. // throw ex; 
    
    

    ---

62. } 
    
    

    ---

63. ---

64. return (T)attr; 
    
    

    ---

65. } 
    
    

    ---

66. ---

67. /// <summary> 
    
    

    ---

68. ///  
    
    

    ---

69. /// </summary> 
    
    

    ---

70. /// <param name="args"></param> 
    
    

    ---

71. public static void Main(String[] args) 
    
    

    ---

72. { 
    
    

    ---

73. var enum1 = TypeEnum.Active; 
    
    

    ---

74. Console.WriteLine(GetAttribute<EnumText>(enum1).Text); 
    
    

    ---

75. ---

76. Console.WriteLine("输入任意键结束"); 
    
    

    ---

77. Console.ReadKey(); 
    
    

    ---

78. ---

79. } 
    
    

    ---

80. } 
    
    

    ---

2、为协议号添加描述

2.1、继承同一接口的协议号类

1. public interface IProtocol { } 
   
   

   ---

2. ---

3. /// <summary> 
   
   

   ---

4. /// 协议号 
   
   

   ---

5. /// </summary> 
   
   

   ---

6. public class Protocol:IProtocol 
   
   

   ---

7. { 
   
   

   ---

8. //... ... 
   
   

   ---

9. ---

10. /// <summary> 
    
    

    ---

11. /// 登录 
    
    

    ---

12. /// </summary> 
    
    

    ---

13. [IProtocolDesc("登录")]  
    
    

    ---

14. public const int Login = 2501; 
    
    

    ---

15. ---

16. //... ...  
    
    

    ---

17. } 
    
    

    ---

2.2、通过反射来得到协议对应值的描述

1. [AttributeUsage(AttributeTargets.Field)] 
   
   

   ---

2. public sealed class IProtocolDescAttribute : Attribute 
   
   

   ---

3. { 
   
   

   ---

4. public string Descripiton { get; } 
   
   

   ---

5. ---

6. public IProtocolDescAttribute(string des) : base() 
   
   

   ---

7. { 
   
   

   ---

8. Descripiton = des; 
   
   

   ---

9. } 
   
   

   ---

10. } 
    
    

    ---

11. ---

12. public static class IProtocolDesHelper 
    
    

    ---

13. { 
    
    

    ---

14. public static string GetDes(int value) 
    
    

    ---

15. { 
    
    

    ---

16. string des = value.ToString(); 
    
    

    ---

17. BindingFlags binding = BindingFlags.Static | BindingFlags.Public;//const值为静态类型，这里作为限定 
    
    

    ---

18. ---

19. Assembly ass=Assembly.GetAssembly(typeof(IProtocol)); 
    
    

    ---

20. Type[] types = ass.GetTypes(); 
    
    

    ---

21. List<Type> protocalTypes=new List<Type>(); 
    
    

    ---

22. foreach (var type in types) 
    
    

    ---

23. { 
    
    

    ---

24. if (type.IsInterface) continue; 
    
    

    ---

25. Type[] ins = type.GetInterfaces(); 
    
    

    ---

26. foreach (var item in ins) 
    
    

    ---

27. { 
    
    

    ---

28. if(item==typeof(IProtocol)&&!protocalTypes.Contains(type)) 
    
    

    ---

29. protocalTypes.Add(type);//挑选出实现IProtocol类型的实例 
    
    

    ---

30. } 
    
    

    ---

31. } 
    
    

    ---

32. ---

33. foreach (var protocalType in protocalTypes) 
    
    

    ---

34. { 
    
    

    ---

35. var fieldInfos = protocalType.GetFields(binding); 
    
    

    ---

36. foreach (var fieldInfo in fieldInfos) 
    
    

    ---

37. { 
    
    

    ---

38. var feildvalue = fieldInfo.GetValue(protocalType); 
    
    

    ---

39. int rel; 
    
    

    ---

40. if (int.TryParse(feildvalue.ToString(), out rel)) 
    
    

    ---

41. { 
    
    

    ---

42. if (rel == value) 
    
    

    ---

43. { 
    
    

    ---

44. var att = fieldInfo.GetCustomAttributes(typeof(IProtocolDescAttribute), false) as IProtocolDescAttribute[]; 
    
    

    ---

45. if (att != null && att.Length > 0) 
    
    

    ---

46. return att[0].Descripiton; 
    
    

    ---

47. } 
    
    

    ---

48. } 
    
    

    ---

49. ---

50. } 
    
    

    ---

51. } 
    
    

    ---

52. ---

53. return des; 
    
    

    ---

54. } 
    
    

    ---

55. } 
    
    

    ---

六、反射使用

1、反射与泛型

1. using System; 
   
   

   ---

2. using System.Collections.Generic; 
   
   

   ---

3. using System.Reflection; 
   
   

   ---

4. using UnityEngine; 
   
   

   ---

5. ---

6. public class TestGneric : MonoBehaviour 
   
   

   ---

7. { 
   
   

   ---

8. // Start is called before the first frame update 
   
   

   ---

9. void Start() 
   
   

   ---

10. { 
    
    

    ---

11. GetTypeOfGeneric(); 
    
    

    ---

12. } 
    
    

    ---

13. ---

14. //获取泛型和已构造的Type对象的各种方式 
    
    

    ---

15. public void GetTypeOfGeneric() 
    
    

    ---

16. { 
    
    

    ---

17. string listTypeName = "System.Collections.Generic.List`1"; 
    
    

    ---

18. Type defByName = Type.GetType(listTypeName); 
    
    

    ---

19. Type closedByName = Type.GetType(listTypeName + "[System.String]"); 
    
    

    ---

20. Type closedByMethod = defByName.MakeGenericType(typeof(string)); 
    
    

    ---

21. Type closedByTypeof = typeof(List<string>); 
    
    

    ---

22. ---

23. Debug.Log(closedByMethod==closedByName);//True 
    
    

    ---

24. Debug.Log(closedByTypeof==closedByName);//True 
    
    

    ---

25. ---

26. Type defByTypeof = typeof(List<>); 
    
    

    ---

27. Type defByMethod = closedByName.GetGenericTypeDefinition(); 
    
    

    ---

28. ---

29. Debug.Log(defByMethod==defByName);//True 
    
    

    ---

30. Debug.Log(defByTypeof==defByName);//True 
    
    

    ---

31. } 
    
    

    ---

32. ---

33. public static void PrintTypeParameter<T>() 
    
    

    ---

34. { 
    
    

    ---

35. Debug.Log(typeof(T)); 
    
    

    ---

36. } 
    
    

    ---

37. ---

38. public void InvokeGenericByRf() 
    
    

    ---

39. { 
    
    

    ---

40. Type type = typeof(TestGneric); 
    
    

    ---

41. //从泛型类型定义获取的方法不能直接调用， 
    
    

    ---

42. MethodInfo definition = type.GetMethod("PrintTypeParameter"); 
    
    

    ---

43. //必须从一个已构造的类型获取方法 
    
    

    ---

44. MethodInfo constructed = definition.MakeGenericMethod(typeof(string)); 
    
    

    ---

45. constructed.Invoke(null, null); 
    
    

    ---

46. } 
    
    

    ---

47. } 
    
    

    ---

48. ---