C#进程间通讯技术-整理。

const int INVALID_HANDLE_VALUE = -1;
const int PAGE_READWRITE = 0x04;
  //共享内存
  [DllImport("Kernel32.dll",EntryPoint="CreateFileMapping")]
  private static extern IntPtr CreateFileMapping(IntPtr hFile, //HANDLE hFile,
   UInt32 lpAttributes,//LPSECURITY_ATTRIBUTES lpAttributes,  //0
   UInt32 flProtect,//DWORD flProtect
   UInt32 dwMaximumSizeHigh,//DWORD dwMaximumSizeHigh,
   UInt32 dwMaximumSizeLow,//DWORD dwMaximumSizeLow,
   string lpName//LPCTSTR lpName
   ); 

  [DllImport("Kernel32.dll",EntryPoint="OpenFileMapping")]
  private static extern IntPtr OpenFileMapping(
   UInt32 dwDesiredAccess,//DWORD dwDesiredAccess,
   int bInheritHandle,//BOOL bInheritHandle,
   string lpName//LPCTSTR lpName
   ); 

  const int FILE_MAP_ALL_ACCESS = 0x0002;
  const int FILE_MAP_WRITE = 0x0002; 

  [DllImport("Kernel32.dll",EntryPoint="MapViewOfFile")]
  private static extern IntPtr MapViewOfFile(
   IntPtr hFileMappingObject,//HANDLE hFileMappingObject,
   UInt32 dwDesiredAccess,//DWORD dwDesiredAccess
   UInt32 dwFileOffsetHight,//DWORD dwFileOffsetHigh,
   UInt32 dwFileOffsetLow,//DWORD dwFileOffsetLow,
   UInt32 dwNumberOfBytesToMap//SIZE_T dwNumberOfBytesToMap
   ); 

  [DllImport("Kernel32.dll",EntryPoint="UnmapViewOfFile")]
  private static extern int UnmapViewOfFile(IntPtr lpBaseAddress); 

  [DllImport("Kernel32.dll",EntryPoint="CloseHandle")]
  private static extern int CloseHandle(IntPtr hObject);
 然后分别在AB两个进程中定义如下两个信号量及相关变量；
 

  private Semaphore m_Write;  //可写的信号
  private Semaphore m_Read;  //可读的信号
  private IntPtr handle;     //文件句柄
  private IntPtr addr;       //共享内存地址
  uint mapLength;            //共享内存长

定义这两个信号量是为读写互斥用的。
在A进程中创建共享内存：
 

m_Write = new Semaphore(1,1,"WriteMap");
m_Read = new Semaphore(0,1,"ReadMap");
mapLength = 1024;
IntPtr hFile = new IntPtr(INVALID_HANDLE_VALUE);   
handle = CreateFileMapping(hFile,0,PAGE_READWRITE,0,mapLength,"shareMemory");
addr = MapViewOfFile(handle,FILE_MAP_ALL_ACCESS,0,0,0);
 
然后再向共享内存中写入数据：
 

m_Write.WaitOne();
byte[] sendStr = Encoding.Default.GetBytes(txtMsg.Text + '/0');
//如果要是超长的话，应另外处理，最好是分配足够的内存
if(sendStr.Length < mapLength)
      Copy(sendStr,addr);
m_Read.Release();
 

这是在一个单独的方法中实现的，可多次调用，但受信号量的控制。其中txtMsg是一个文本框控件，实际中可用任意字符串，加最后的'/0'是为了让在共享内存中的字符串有一个结束符，否则在内存中取出时是以'/0'为准的，就会出现取多的情况。
Copy方法的实现如下：
 

static unsafe void Copy(byte[] byteSrc,IntPtr dst)
  {
   fixed (byte* pSrc = byteSrc)
   {
    byte* pDst = (byte*)dst;
    byte* psrc = pSrc;
    for(int i=0;i<byteSrc.Length;i++)
    {
     *pDst = *psrc;
     pDst++;
     psrc ++;
    }
   }
  }
 注意unsafe 关键字，在编译时一定要打开非安全代码开关。
最后不要忘了在A进程中关闭共享内存对象，以免内存泄露。
 

   UnmapViewOfFile(addr);
   CloseHandle(handle);
 
要在B进程中读取共享内存中的数据，首先要打开共享内存对象：
 

m_Write = Semaphore.OpenExisting("WriteMap");
m_Read = Semaphore.OpenExisting("ReadMap");
handle = OpenFileMapping(0x0002,0,"shareMemory");
 读取共享内存中的数据：
 

   m_Read.WaitOne();
   string str = MapViewOfFile(handle,FILE_MAP_ALL_ACCESS,0,0,0);
   txtMsg.Text = str;
   m_Write.Release();
 这里获取了字符串，如果要获取byte数组，请参考上面的Copy函数实现。