23、Windows API 进程间通信，数据复制消息(WM_COPYDATA)

    WM_COPYDATA是一个非常特殊的消息，此消息可能携带一个比较大的消息参数，而其他消息都只能携带两个固定大小的参数(WPARAM和LPARAM)。

在发送WM_COPYDATA消息时，WM_COPYDATA的wParam参数应该赋值为发送此消息的窗口，而lParam消息参数指向一个COPYDATASTRUCT结构类型的变量。

typedef struct tagCOPYDATASTRUCT {

    ULONG_PTR dwData;

    DWORD     cbData;

    PVOID     lpData;

} COPYDATASTRUCT, *PCOPYDATASTRUCT;

dwData可以是任意值，lpData是需要发送给目录窗口所在进程的数据，cbData字符指定了lpData内存区域的字节数，也就是需要发送给目标进程的lpData所指向的数据的大小。

在消息发送时，系统会将整个COPYDATASTRUCT及lpData所指向的内容全部发送给目标进程。目标进程窗口在收到WM_COPYDATA后，可以从lParam参数中提取出数据。

1、一个例子

数据发送端

通过WM_COPYDATA进程间通信
**************************************/
/* 头文件 */
#include <windows.h> 
#include <commctrl.h>
#include "resource.h"
/* 全局变量 */
HINSTANCE hinst;
HWND hwnd, hwndEdit;
LPSTR lpszCopy =  "you can input any text\n then click \'Send\' Item at Menu"; 
/* 函数声明 */
int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int); 
LRESULT CALLBACK MainWndProc(HWND, UINT, WPARAM, LPARAM); 

/* ************************************
* WinMain
**************************************/
int WINAPI WinMain(
                   HINSTANCE hinstance, 
                   HINSTANCE hPrevInstance, 
                   LPSTR lpCmdLine,
                   int nCmdShow) 
{ 
    MSG msg; 
    WNDCLASSEX wcx; 

    hinst = hinstance;    // 保存应用程序实例

    // 填充WNDCLASSEX
    wcx.cbSize = sizeof(wcx);      
    wcx.style = CS_HREDRAW | CS_VREDRAW;                   
    wcx.lpfnWndProc = MainWndProc;        // 消息处理函数
    wcx.cbClsExtra = 0;        
    wcx.cbWndExtra = 0;             
    wcx.hInstance = hinstance;   
    wcx.hIcon = LoadIcon(NULL,     IDI_APPLICATION);          
    wcx.hCursor = LoadCursor(NULL, IDC_ARROW);                 
    wcx.hbrBackground = (HBRUSH)GetStockObject( WHITE_BRUSH);               
    wcx.lpszMenuName =  MAKEINTRESOURCE(IDR_MENU_COMMAND);   // 菜单
    wcx.lpszClassName = "copydata";        // 窗口类名
    wcx.hIconSm = NULL; 
    // 注册窗口类
    if(RegisterClassEx(&wcx) == 0)
    {
        return 0;
    }
    // 创建窗口
    hwnd = CreateWindow( 
        "copydata",        
        "Sample",           
        WS_TILEDWINDOW, 
        CW_USEDEFAULT, CW_USEDEFAULT, 500,     400,    
        (HWND) NULL,        
        (HMENU) NULL,      
        hinstance,         
        (LPVOID) NULL);    
    if (!hwnd) 
        return 0; 

    // 显示、刷新窗口
    ShowWindow(hwnd, nCmdShow); 
    UpdateWindow(hwnd); 
    // 消息循环

    BOOL fGotMessage;
    while ((fGotMessage = GetMessage(&msg, (HWND) NULL, 0, 0)) != 0 && fGotMessage != -1) 
    { 
        TranslateMessage(&msg); 
        DispatchMessage(&msg); 
    } 
    return msg.wParam; 
    UNREFERENCED_PARAMETER(lpCmdLine); 
} 

/* ************************************
* 消息处理函数
**************************************/
LONG APIENTRY MainWndProc(HWND hwnd,          
                          UINT message,           
                          WPARAM wParam,         
                          LPARAM lParam)          
{ 
    switch (message) 
    { 
    case WM_CREATE:
        {
            // 在主窗口创建时，创建一个EDIT控件，用于编辑需要复制的内容
            RECT rectMain;
            GetClientRect(hwnd,&rectMain);
            hwndEdit = CreateWindow("EDIT",    
                NULL,       
                WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_BORDER |
                ES_LEFT | ES_MULTILINE | ES_AUTOVSCROLL, 
                0., 0, rectMain.right, rectMain.bottom, 
                hwnd,      NULL,
                (HINSTANCE) GetWindowLong(hwnd, GWL_HINSTANCE), 
                NULL);     
            if(hwndEdit == NULL)
            {
                MessageBox(hwnd, "Create Window Error","ERROR",MB_OK);
                ExitProcess(0);
            }
            // 设置EDIT控件的内容
            SendMessage(hwndEdit, WM_SETTEXT, 0, (LPARAM) lpszCopy); 
            break;
        }
    case WM_COMMAND:        // 菜单输入
        {
            // 如果通过菜单点击“send”按钮
            if (LOWORD(wParam) == ID_COMMAND_SEND) 
            {
                // 获取EDIT控件中的文本
                DWORD dwTextLenth = GetWindowTextLength(hwndEdit);
                LPSTR szText = (LPSTR)HeapAlloc(GetProcessHeap(),HEAP_NO_SERIALIZE,dwTextLenth);
                GetWindowText(hwndEdit,szText,dwTextLenth);
                // 构造 COPYDATASTRUCT
                COPYDATASTRUCT cds;
                HWND hwnd2 = FindWindow("copydata2","RECV COPY DATA");
                if(hwnd2 == NULL)
                {
                    MessageBox(hwnd,"can not find window 2","ERROR",MB_OK);
                    break;
                }
                cds.dwData = 0x12345678;            // 自定义的数据
                cds.cbData = dwTextLenth;        // lpData的长度
                cds.lpData = szText;                // 需要复制的数据
                // 发送消息，COPYDATASTRUCT结构的指针做为lParam
                SendMessage(    
                    hwnd2,                                    // 目的窗口
                    (UINT) WM_COPYDATA,        // 消息 ID
                    (WPARAM) hwnd,        //  wParam，源窗口句柄
                    (LPARAM) &cds            //  lParam，COPYDATASTRUCT
                    ); 
                // 释放内存                    
                HeapFree(GetProcessHeap(),HEAP_NO_SERIALIZE,szText);
            } 
            break; 
        }
    case WM_DESTROY:    // 退出
        PostQuitMessage(0); 
        return 0; 

    default:        // 其他消息的处理
        return DefWindowProc(hwnd, message, wParam, lParam); 
    }
return 0; 
}

数据接收端

通过WM_COPYDATA进程间通信
**************************************/
/* 头文件 */
#include <windows.h>
#include <commctrl.h>
/* 全局变量 */
HINSTANCE hinst;
HWND hwnd,hwndEdit;
/* 函数声明 */
int WINAPI WinMain(HINSTANCE, HINSTANCE, LPSTR, int);
LRESULT CALLBACK MainWndProc(HWND, UINT, WPARAM, LPARAM);

/* ************************************
* void main()
* 功能 进程间mailslot通信客户端
**************************************/
int WINAPI WinMain(
                   HINSTANCE hinstance,
                   HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,
                   int nCmdShow)
{
    MSG msg;
    WNDCLASSEX wcx;
    // 填充WNDCLASSEX
    wcx.cbSize = sizeof(wcx);
    wcx.style = CS_HREDRAW | CS_VREDRAW;
    wcx.lpfnWndProc = MainWndProc;
    wcx.cbClsExtra = 0;
    wcx.cbWndExtra = 0;
    wcx.hInstance = hinstance;
    wcx.hIcon = LoadIcon(NULL, IDI_APPLICATION);
    wcx.hCursor = LoadCursor(NULL, IDC_ARROW);
    wcx.hbrBackground = (HBRUSH)GetStockObject( WHITE_BRUSH);
    wcx.lpszMenuName = NULL;
    wcx.lpszClassName = "copydata2";
    wcx.hIconSm = NULL;
    // 注册窗口类
    if(RegisterClassEx(&wcx) == 0)
    {
        return 0;
    }
    // 创建窗口
    hwnd = CreateWindow(
        "copydata2",
        "RECV COPY DATA",
        WS_TILEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 500, 400,
        (HWND) NULL, (HMENU) NULL, hinstance, (LPVOID) NULL
        );

    if (!hwnd)
        return 0;
    // 显示刷新窗口
    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);
    // 消息
    BOOL fGotMessage;
    while ((fGotMessage = GetMessage(&msg, (HWND) NULL, 0, 0)) != 0 && fGotMessage != -1)
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    return msg.wParam;
    UNREFERENCED_PARAMETER(lpCmdLine);
    return 0;
}

// 消息处理函数
LONG APIENTRY MainWndProc(HWND hwnd,
                          UINT message,
                          WPARAM wParam,
                          LPARAM lParam)
{
    switch (message)
    {
    case WM_CREATE:
        {
            // 创建主窗口时，创建一个EDIT控件
            RECT rectMain;
            GetClientRect(hwnd,&rectMain);
            hwndEdit = CreateWindow("EDIT",
                NULL,
                WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_BORDER |
                ES_LEFT | ES_MULTILINE | ES_AUTOVSCROLL,
                0., 0, rectMain.right, rectMain.bottom,
                hwnd,
                NULL,
                (HINSTANCE) GetWindowLong(hwnd, GWL_HINSTANCE),
                NULL);
            if(hwndEdit == NULL)
            {
                MessageBox(hwnd, "Create Window Error","ERROR",MB_OK);
                ExitProcess(0);
            }
            break;
    case WM_COPYDATA:
        {
            // 当收到WM_COPYDATA消息时，从lParam中提取出
            // COPYDATASTRUCT
            PCOPYDATASTRUCT lpcds = (PCOPYDATASTRUCT)lParam;
            // 将复制的数据在界面上显示
            SetWindowText(hwndEdit,(LPSTR)lpcds->lpData);
            break;
        }

    case WM_DESTROY: // 退出
        PostQuitMessage(0);
        return 0;

    default: // 其他消息处理
        break;
        }
    }
    return DefWindowProc(hwnd, message, wParam, lParam);
}

Interprocess Communications[2]

参考

[1] 精通Windows API 函数、接口、编程实例

[2] http://msdn.microsoft.com/en-us/library/ms648710%28VS.85%29.aspx