C# 进程间通信(共享内存)

原文:C# 进程间通信(共享内存)进程间通信的方式有很多，常用的方式有：

1.共享内存（内存映射文件，共享内存DLL）。

2.命名管道和匿名管道。

3.发送消息

本文是记录共享内存的方式进行进程间通信，首先要建立一个进程间共享的内存地址，创建好共享内存地址后，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。

在数据的读写的过程中要进行进程间的同步。

进程间数据同步可以有以下的方式

1. 互斥量Mutex

2. 信号量Semaphore

3. 事件Event

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

在A进程中创建共享内存，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;

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

//线程用来读取数据 Thread threadRed;
public AppOneMain()
{
InitializeComponent();
init();
}

///<summary>/// 初始化共享内存数据 创建一个共享内存
///</summary>privatevoid init()
{
m_Write = new Semaphore(1, 1, "WriteMap");//开始的时候有一个可以写
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允许不安全代码
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');
//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();

}
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++;
}
}
}

}
}