如何進(jìn)行在C#中SendMessage和PostMessage的參數(shù)傳遞

這篇文章將為大家詳細(xì)講解有關(guān)如何進(jìn)行在C#中SendMessage和PostMessage的參數(shù)傳遞，文章內(nèi)容質(zhì)量較高，因此小編分享給大家做個(gè)參考，希望大家閱讀完這篇文章后對相關(guān)知識有一定的了解。

在C#中可以使用Window API提供的SendMessage和PostMessage來傳遞參數(shù)。兩者的區(qū)別簡單介紹下：返回值的不同，我們先看一下 MSDN 里的聲明：
LRESULT SendMessage(

HWND hWnd,

UINT Msg,

WPARAM wParam,

LPARAM lParam

);

BOOL PostMessage(

HWND hWnd,

UINT Msg,

WPARAM wParam,

LPARAM lParam

);

其中 4 個(gè)參數(shù)的意義是一樣的，返回值類型不同（其實(shí)從數(shù)據(jù)上看他們一樣是一個(gè) 32 位的數(shù)，只是意義不一樣），LRESULT 表示的是消息被處理后的返回值，BOOL 表示的是消息是不是 Post 成功。

2、PostMessage 是異步的，SendMessage 是同步的。
PostMessage 只把消息放入隊(duì)列，不管消息是否被處理就返回，消息可能不被處理；而 SendMessage 等待消息被處理完了之后才返回，如果消息不被處理，發(fā)送消息的線程將一直被阻塞。

3、如果在同一個(gè)線程內(nèi)，SendMessage 發(fā)送消息時(shí)，由 USER32.DLL
模塊調(diào)用目標(biāo)窗口的消息處理程序，并將結(jié)果返回。SendMessage 在同一線程中發(fā)送消息并不入線程消息隊(duì)列。PostMessage
發(fā)送消息時(shí)，消息要先放入線程的消息隊(duì)列，然后通過消息循環(huán)分派到目標(biāo)窗口（DispatchMessage）。

如果在不同線程內(nèi)，SendMessage 發(fā)送消息到目標(biāo)窗口所屬線程的消息隊(duì)列，然后發(fā)送消息的線程在 USER32.DLL
模塊內(nèi)監(jiān)視和等待消息處理，直到目標(biāo)窗口處理完返回。SendMessage 在返回前還做了很多工作，比如，響應(yīng)別的線程向它
SendMessage。Post 到別的線程時(shí)，最好用 PostThreadMessage 代替
PostMessage，PostMessage 的 hWnd 參數(shù)可以是 NULL，等效于 PostThreadMessage +
GetCurrentThreadId。Post WM_QUIT 時(shí)，應(yīng)使用 PostQuitMessage 代替。

4、系統(tǒng)只整編（marshal）系統(tǒng)消息（0 到 WM_USER 之間的消息），發(fā)送用戶消息（WM_USER 以上）到別的進(jìn)程時(shí)，需要自己做整編。

用 PostMessage、SendNotifyMessage、SendMessageCallback 等異步函數(shù)發(fā)送系統(tǒng)消息時(shí)，參數(shù)里不可以使用指針，因?yàn)榘l(fā)送者并不等待消息的處理就返回，接受者還沒處理指針就已經(jīng)被釋放了。 5、在 Windows 2000/XP 里，每個(gè)消息隊(duì)列最多只能存放 10,000 個(gè) Post 的消息，超過的還沒被處理的將不會被處理，直接丟掉。這個(gè)值可以改得更大：[HKEY_LOCAL_MACHINE/SOFTWARE/ Microsoft/Windows NT/CurrentVersion/Windows] USERPostMessageLimit，最小可以是 4000。 PostMessage只負(fù)責(zé)將消息放到消息隊(duì)列中，不確定何時(shí)及是否處理 SendMessage要等到受到消息處理的返回碼（DWord類型）后才繼續(xù) PostMessage執(zhí)行后馬上返回 SendMessage必須等到消息被處理后才會返回。 下面通過一個(gè)小例子來說明下這2個(gè)方法進(jìn)行參數(shù)傳遞的不同點(diǎn)：
//Win32 API 類

using System;
using System.Runtime.InteropServices;

namespace TestHwnd
{
    public class Win32API
    {
       

        [DllImport("User32.dll", EntryPoint = "FindWindow")]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("User32.dll", EntryPoint = "FindWindowEx")]
        public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpClassName, string lpWindowName);

        /// <summary>
        /// 自定義的結(jié)構(gòu)
        /// </summary>

       // 注意：必須是結(jié)構(gòu)體不能是類即必須為struct關(guān)鍵字不能是class,否則在接收消息時(shí)會產(chǎn)生異常 
        public struct My_lParam        
        {
            public int i;
            public string s;
        }
        /// <summary>
        /// 使用COPYDATASTRUCT來傳遞字符串
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct COPYDATASTRUCT
        {
            public IntPtr dwData;
            public int cbData;
            [MarshalAs(UnmanagedType.LPStr)]
            public string lpData;
        }
        //消息發(fā)送API
        [DllImport("User32.dll", EntryPoint = "SendMessage")]
        public static extern int SendMessage(
            IntPtr hWnd,        // 信息發(fā)往的窗口的句柄
            int Msg,            // 消息ID
            int wParam,         // 參數(shù)1
            int lParam          //參數(shù)2
        );

       
        //消息發(fā)送API
        [DllImport("User32.dll", EntryPoint = "SendMessage")]
        public static extern int SendMessage(
            IntPtr hWnd,        // 信息發(fā)往的窗口的句柄
            int Msg,            // 消息ID
            int wParam,         // 參數(shù)1
            ref My_lParam lParam //參數(shù)2
        );
       
        //消息發(fā)送API
        [DllImport("User32.dll", EntryPoint = "SendMessage")]
        public static extern int SendMessage(
            IntPtr hWnd,        // 信息發(fā)往的窗口的句柄
            int Msg,            // 消息ID
            int wParam,         // 參數(shù)1
            ref  COPYDATASTRUCT lParam  //參數(shù)2
        );

        //消息發(fā)送API
        [DllImport("User32.dll", EntryPoint = "PostMessage")]
        public static extern int PostMessage(
            IntPtr hWnd,        // 信息發(fā)往的窗口的句柄
            int Msg,            // 消息ID
            int wParam,         // 參數(shù)1
            int lParam            // 參數(shù)2
        );
       
       
       
        //消息發(fā)送API
        [DllImport("User32.dll", EntryPoint = "PostMessage")]
        public static extern int PostMessage(
            IntPtr hWnd,        // 信息發(fā)往的窗口的句柄
            int Msg,            // 消息ID
            int wParam,         // 參數(shù)1
            ref My_lParam lParam //參數(shù)2
        );
       
        //異步消息發(fā)送API
        [DllImport("User32.dll", EntryPoint = "PostMessage")]
        public static extern int PostMessage(
            IntPtr hWnd,        // 信息發(fā)往的窗口的句柄
            int Msg,            // 消息ID
            int wParam,         // 參數(shù)1
            ref  COPYDATASTRUCT lParam  // 參數(shù)2
        );

    }
}

//主窗體，發(fā)送消息

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace TestHwnd
{
    public partial class Main : Form
    {

        public IntPtr hwndTest;
        public int IwndTest;
        public IntPtr hwndfrmTest;
       

        public Main()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Test test = new Test();
            test.Show(this);
        }

        private void timer1_Tick(object sender, EventArgs e)
        {
            string strTest = "25425";
            Win32API.COPYDATASTRUCT cds;
            cds.dwData = (IntPtr)100;
            cds.lpData = strTest;
            byte[] sarr = System.Text.Encoding.UTF8.GetBytes(strTest);
            int len = sarr.Length;
            cds.cbData = len + 1;
           
            Win32API.My_lParam lp=new Win32API.My_lParam();
            lp.i=3;
            lp.s="test";
           
            if(hwndTest!=(IntPtr)0)
            {
                if (DateTime.Now.Second % 2 == 0)
                {
                    Win32API.SendMessage(hwndTest, 0x60, 1, 3);//傳遞2個(gè)整型參數(shù)成功
                }
                if(DateTime.Now.Second % 3 == 0)
                {
                    Win32API.SendMessage(hwndTest, 0x61, 5, ref lp);//傳遞整型參數(shù)和結(jié)構(gòu)類型成功，這個(gè)方法加以改變后可以傳遞對象
                }
                if(DateTime.Now.Second % 5 == 0)
                {
                    Win32API.SendMessage(hwndTest, 0x62, 5, ref cds);//傳遞整型參數(shù)和不定長的字符串成功
                }
                if(DateTime.Now.Second % 7 == 0)
                {
                    Win32API.PostMessage(hwndTest, 0x63, 5, 6);//傳遞2個(gè)整型參數(shù)成功
                }
                if(DateTime.Now.Second % 9 == 0)
                {
                    Win32API.PostMessage(hwndTest, 0x64, 3, ref lp);//傳遞整型參數(shù)成功，但是傳遞參數(shù)lp失敗，3可以傳遞成功。
                }
                if(DateTime.Now.Second % 11 == 0)
                {
                    Win32API.PostMessage(hwndTest, 0x65, 3, ref cds);//傳遞整型參數(shù)成功，傳遞參數(shù)cds失敗，3可以傳遞成功。
                }
            }
           
           
        }
    }
}

//子窗體接收消息以及參數(shù)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace TestHwnd
{
    public partial class Test : Form
    {
        Main main;
        public Test()
        {
            InitializeComponent();
        }

        private void Test_Load(object sender, EventArgs e)
        {
            main = this.Owner as Main;
            main.hwndTest = this.Handle;
           
        }

        ///重寫窗體的消息處理函數(shù)DefWndProc，從中加入自己定義消息的檢測的處理入口
        protected override void DefWndProc(ref Message m)
        {
            switch (m.Msg)
            {
                    //接收自定義消息MYMESSAGE，并顯示其參數(shù)
                case 0x60:
                    {
                        label1.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + m.LParam.ToInt32().ToString();
                    }
                    break;
                case 0x61:
                    {
                        Win32API.My_lParam ml = new Win32API.My_lParam();
                        Type t = ml.GetType();
                        ml = (Win32API.My_lParam)m.GetLParam(t);
                        label2.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + ml.i.ToString()+":"+ml.s;
                    }
                    break;
                    case 0x62:
                    {
                        Win32API.COPYDATASTRUCT mystr = new Win32API.COPYDATASTRUCT();
                        Type mytype = mystr.GetType();
                        mystr = (Win32API.COPYDATASTRUCT)m.GetLParam(mytype);
                        string str2 = mystr.lpData;
                        label3.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + str2;
                    }
                    break;
                    case 0x63:
                    {
                        label4.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + m.LParam.ToInt32().ToString();
                    }
                    break;
                    case 0x64:
                    {
                        Win32API.My_lParam ml = new Win32API.My_lParam();
                        Type t = ml.GetType();
                        ml = (Win32API.My_lParam)m.GetLParam(t);
                        label5.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + ml.i.ToString()+":"+ml.s;
                    }
                    break;
                    case 0x65:
                    {
                        Win32API.COPYDATASTRUCT mystr = new Win32API.COPYDATASTRUCT();
                        Type mytype = mystr.GetType();
                        mystr = (Win32API.COPYDATASTRUCT)m.GetLParam(mytype);
                        string str2 = mystr.lpData;
                        label6.Text = DateTime.Now.ToString() + "-" + m.WParam.ToInt32().ToString() + "-" + str2;
                    }
                    break;
                default:
                    base.DefWndProc(ref m);
                    break;
            }
        }

       
        private void button1_Click(object sender, EventArgs e)
        {
            main.hwndTest = (IntPtr) (0);
            this.Close();
        }

    }

   
}

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