C#如何动态加载(调用)DLL?

RT 工作原因,现在手里有很多dll,每个dll都有一个类和一个方法,类名不同,但所有的dll
中的类都实现了一个借口,方法名是相同的,怎样动态调用这些dll? 可不可以写一个小例子

2个回答

C#调用C++编写的DLL函数各种参数传递问题

  1. 不返回值的参数

  C++ 原型:

  bool SendNewSms(char *szTel, char *szMessage);

  C#引用;

  [DllImport( "CdmaCard.dll",EntryPoint="SendNewSms")]

  public static extern bool SendNewSms(string phone,string msg);

  2. 带返回值(char *)

  C++原型:

  BOOL GetCardErrorMessage(char *szErrorMessage , int errorCode);

  C#引用

  [DllImport( "CdmaCard.dll",EntryPoint="GetCardErrorMessage")]

  public static extern int GetCardErrorMessage(StringBuilder msg,int errorCode);

  StringBuilder buf = new StringBuilder(1024);//指定的Buf大小必须大于可能的最大长度

  GetCardErrorMessage(buf,1);

  3. 带返回值(其他类型)

  C++原型:

  BOOL GetSmsSaveStation (int *nSmsStation);

  C#引用

  [DllImport( "CdmaCard.dll",EntryPoint="GetSmsSaveStation")]

  public static extern bool GetSmsSaveStation(ref int nStation);

  4. 传递结构体指针(C++填充)

  C++原型:

  struct NET_INFO_STRUCT

  {

  DWORD nDurationTime; //持续时间

  double nReceiveByte; //接收字节

  double nSendByte; //发送字节

  };

  BOOL NetGetConnectDetail(NET_INFO_STRUCT *lpNetInfo);

  C#引用

  public struct NET_INFO_STRUCT

  {

  public uint nDurationTime; //持续时间

  public double nReceiveByte; //接收字节

  public double nSendByte; //发送字节

  }

  [DllImport( "CdmaCard.dll",EntryPoint="NetGetConnectDetail")]

  public static extern int NetGetConnectDetail(ref NET_INFO_STRUCT pNetInfo);

  NET_INFO_STRUCT netInfo = new NET_INFO_STRUCT();

  NetGetConnectDetail(ref netInfo);

  5. 传递结构体数组(C++来填充)

  C++原型:

  struct UIM_BOOK_STRUCT

  {

  int UimIndex;

  char szName[15];

  char szPhone[21];

  };

  int ReadUimAllBook(UIM_BOOK_STRUCT lpUimBookItem[],int nMaxArraySize);

  C#引用

  [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]//可以指定编码类型

  public struct UIM_BOOK_STRUCT

  {

  public int UimIndex;

  [MarshalAs(UnmanagedType.ByValTStr, SizeConst= 15)]

  public string szName;

  [MarshalAs(UnmanagedType.ByValTStr, SizeConst= 21)]

  public string szPhone;

  };

  [DllImport( "CdmaCard.dll",EntryPoint="ReadUimAllBook")]

  public static extern int ReadUimAllBook([Out] UIM_BOOK_STRUCT [] lpUimBookItem,int nMaxArraySize);

  UIM_BOOK_STRUCT[] p = new UIM_BOOK_STRUCT[20];

  int ret = ReadUimAllBook(p,p.Length);

  6. 注意问题

  类型不一致,会导致调用失败,

  (1) long 类型,在C++中是4字节的整数,在C#中是8字节的整数;

  (2) 字符串类型的设置不正确;

  以下是几个简单的window调用

  [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously

  [DllImport("User32.dll", CharSet=CharSet.Auto)]

  public static extern bool ScreenToClient(IntPtr hWnd, ref System.Drawing.Point rect);

  [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously

  [DllImport("User32.dll", CharSet=CharSet.Auto)]

  public static extern bool GetWindowRect(IntPtr hWnd, out System.Drawing.Rectangle rect);

  [System.Security.SuppressUnmanagedCodeSecurity] // We won't use this maliciously

  [DllImport("User32.dll", CharSet=CharSet.Auto)]

  public static extern bool UnregisterClass([MarshalAs(UnmanagedType.LPTStr)] string className, IntPtr instanceHandle);

有个技术叫 “反射” 你去研究下吧

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