C# 进程间通讯(共享内存)

时间 2019-11-25

标签 c# 进程通讯共享内存栏目 C# 繁體版

原文原文链接

进程间通讯的方式有不少，经常使用的方式有：c++

1.共享内存（内存映射文件，共享内存DLL）。安全

2.命名管道和匿名管道。app

3.发送消息 ui

本文是记录共享内存的方式进行进程间通讯，首先要创建一个进程间共享的内存地址，建立好共享内存地址后，一个进程向地址中写入数据，另外的进程从地址中读取数据。spa

在数据的读写的过程当中要进行进程间的同步。操作系统

进程间数据同步能够有如下的方式线程

1. 互斥量Mutexcode

2. 信号量Semaphoreorm

3. 事件Event blog

本文中进程间的同步采用信号量Semaphore的方式同步思想相似于操做系统中生产者和消费者问题的处理方式。

在A进程中建立共享内存，并开启一个线程用来读取B进程向共享内存中写入的数据，定义两个信号量进行读写互斥同步

A进程中的程序代码

using System;

        Thread threadRed;
        public AppOneMain()
        {
            InitializeComponent();
            init();
        }

///<summary>/// 初始化共享内存数据建立一个共享内存
        ///</summary>privatevoid init()
        {
            m_Write = new Semaphore(1, 1, "WriteMap");//开始的时候有一个能够写
            m_Read = new Semaphore(0, 1, "ReadMap");//没有数据可读
            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>
        /// 线程启动从共享内存中获取数据信息
        /// </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");

                    //读取共享内存中的数据：
                    //是否有数据写过来
                    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);
                   /////调用数据处理方法处理读取到的数据
                    m_Write.Release();
                }
                catch (WaitHandleCannotBeOpenedException)
                {
                    continue;
                    //Thread.Sleep(0);
                }

            }

        }
        //不安全的代码在项目生成的选项中选中容许不安全代码
        static unsafe void byteCopy(byte[] dst, IntPtr src)
        {
            fixed (byte* pDst = dst)
            {
                byte* pdst = pDst;
                byte* psrc = (byte*)src;
                while ((*pdst++ = *psrc++) != '\0')
                    ;
            }

        }

    }
}

B进程向共享内存中写入的数据

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;

namespace AppTwo
{
     public partial class AppTwoMain : Form
    {
         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);

         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

        Thread threadRed;

         public AppTwoMain()
        {
            InitializeComponent();
             // threadRed = new Thread(new ThreadStart(init));
             // threadRed.Start();
            mapLength = 1024;

        }

         private void button1_Click( object sender, EventArgs e)
        {
             try
            {
                m_Write = Semaphore.OpenExisting( " WriteMap ");
                m_Read = Semaphore.OpenExisting( " ReadMap ");
                handle = OpenFileMapping(FILE_MAP_WRITE, 0, " shareMemory ");
                addr = MapViewOfFile(handle, FILE_MAP_ALL_ACCESS, 0, 0, 0);

                m_Write.WaitOne();
                 byte[] sendStr = Encoding.Default.GetBytes(textBox1.Text.ToString() + ' \0 ');
                 // 若是要是超长的话，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();


            }
             catch (WaitHandleCannotBeOpenedException)
            {
                MessageBox.Show( " 不存在系统信号量! ");
                 return;
            }
        }

         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++;                 }             }         }    } }