Date:2017-7-16

進程間通信的方式有很多，常用的方式有：

1.共享內存（內存映射文件，共享內存DLL）。

2.命名管道和匿名管道。

3.發送消息

本文是記錄共享內存的方式進行進程間通信，首先要建立一個進程間共享的內存地址，創建好共享內存地址後，一個進程向地址中寫入數據，另外的進程從地址中讀取數據。

在數據的讀寫的過程中要進行進程間的同步。

進程間數據同步可以有以下的方式

1. 互斥量Mutex

2. 信號量Semaphore

3. 事件Event

本文中進程間的同步采用 信號量Semaphore的方式同步思想類似於操作系統中生產者和消費者問題的處理方式。

在A進程中創建共享內存，並開啟一個線程用來讀取B進程向共享內存中寫入的數據，定義兩個信號量進行讀寫互斥同步

A進程中的程序代碼

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;
using System.Threading;
using System.Diagnostics;

 
namespace AppOne
{
    public partial class AppOneMain : Form
    {
        const int INVALID_HANDLE_VALUE = -1;
        const int PAGE_READWRITE = 0x04;

        [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
        [DllImport("User32.dll
 
")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);

        //共享內存
        [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);

        private Semaphore m_Write;  //可寫的信號
        private Semaphore m_Read;  //可讀的信號
        private IntPtr handle;     //文件句柄
        private IntPtr addr;       //共享內存地址
        uint mapLength;            //共享內存長

        //線程用來讀取數據        Thread threadRed;
        public AppOneMain()
        {
            InitializeComponent();
            init();
        }    
                ///<summary>/// 初始化共享內存數據 創建一個共享內存
        ///</summary>privatevoid init()
        {
            m_Write = new Semaphore(1, 1, "WriteMap");//開始的時候有一個可以寫
            m_Read = new Semaphore(0, 1, "ReadMap");//沒有數據可讀
            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);

            //handle = OpenFileMapping(0x0002, 0, "shareMemory");
            //addr = MapViewOfFile(handle, FILE_MAP_ALL_ACCESS, 0, 0, 0);

            threadRed = new Thread(new ThreadStart(ThreadReceive));
            threadRed.Start();
        }

        /// <summary>
        /// 線程啟動從共享內存中獲取數據信息 
        /// </summary>
        private void ThreadReceive()
        {
            myDelegate myI = new myDelegate(changeTxt);
            while (true)
            {
                try
                {
                    //m_Write = Semaphore.OpenExisting("WriteMap");
                    //m_Read = Semaphore.OpenExisting("ReadMap");
                    //handle = OpenFileMapping(FILE_MAP_WRITE, 0, "shareMemory");

                    //讀取共享內存中的數據：
                    //是否有數據寫過來
                    m_Read.WaitOne();
                    //IntPtr m_Sender = MapViewOfFile(handle, FILE_MAP_ALL_ACCESS, 0, 0, 0);
                    byte[] byteStr = new byte[100];
                    byteCopy(byteStr, addr);
                    string str = Encoding.Default.GetString(byteStr, 0, byteStr.Length);
                   /////調用數據處理方法 處理讀取到的數據
                    m_Write.Release();
                }
                catch (WaitHandleCannotBeOpenedException)
                {
                    continue;
                    //Thread.Sleep(0);
                }

            }

        }
        //不安全的代碼在項目生成的選項中選中允許不安全代碼
        static unsafe void byteCopy(byte[] dst, IntPtr src)
        {
            fixed (byte* pDst = dst)
            {
                byte* pdst = pDst;
                byte* psrc = (byte*)src;
                while ((*pdst++ = *psrc++) != ‘\0‘)
                    ;
            }

        }

    }
}

記錄一下