1. 源起：
仍然是模块化编程所引发的需求。产品经理难伺候，女产品经理更甚之~:p
纯属戏谑，技术方案与产品经理无关，芋头莫怪！
VCU10项目重构，要求各功能模块以独立进程方式实现，比如：音视频转换模块，若以独立进程方式实现，如何控制其暂停、继续等功能呢？
线程可以Suspend、Resume，c#内置的Process没有此类方法，咋整？
山穷水尽疑无路，柳暗花明又一村。情到浓时清转薄，此情可待成追忆！
前篇描述了进程间数据传递方法，此篇亦以示例演示其间控制与数据交互方法。
2、未公开的API函数：NtSuspendProcess、NtResumeProcess
此类函数在MSDN中找不到。
思其原因，概因它们介于Windows API和 内核API之间，威力不容小觑。怕二八耙子程序员滥用而引发事端，因此密藏。
其实还有个NtTerminateProcess，因Process有Kill方法，因此可不用。
但再隐秘的东西，只要有价值，都会被人给翻出来，好酒不怕巷子深么！
好，基于其，设计一个进程管理类，实现模块化编程之进程间控制这个需求。
3、ProcessMgr
直上代码吧，封装一个进程管理单元：
public static class ProcessMgr { /// <summary> /// The process-specific access rights. /// </summary> [Flags] public enum ProcessAccess : uint { /// <summary> /// Required to terminate a process using TerminateProcess. /// </summary> Terminate = 0x1, /// <summary> /// Required to create a thread. /// </summary> CreateThread = 0x2, /// <summary> /// Undocumented. /// </summary> SetSessionId = 0x4, /// <summary> /// Required to perform an operation on the address space of a process (see VirtualProtectEx and WriteProcessMemory). /// </summary> VmOperation = 0x8, /// <summary> /// Required to read memory in a process using ReadProcessMemory. /// </summary> VmRead = 0x10, /// <summary> /// Required to write to memory in a process using WriteProcessMemory. /// </summary> VmWrite = 0x20, /// <summary> /// Required to duplicate a handle using DuplicateHandle. /// </summary> DupHandle = 0x40, /// <summary> /// Required to create a process. /// </summary> CreateProcess = 0x80, /// <summary> /// Required to set memory limits using SetProcessWorkingSetSize. /// </summary> SetQuota = 0x100, /// <summary> /// Required to set certain information about a process, such as its priority class (see SetPriorityClass). /// </summary> SetInformation = 0x200, /// <summary> /// Required to retrieve certain information about a process, such as its token, exit code, and priority class (see OpenProcessToken, GetExitCodeProcess, GetPriorityClass, and IsProcessInJob). /// </summary> QueryInformation = 0x400, /// <summary> /// Undocumented. /// </summary> SetPort = 0x800, /// <summary> /// Required to suspend or resume a process. /// </summary> SuspendResume = 0x800, /// <summary> /// Required to retrieve certain information about a process (see QueryFullProcessImageName). A handle that has the PROCESS_QUERY_INFORMATION access right is automatically granted PROCESS_QUERY_LIMITED_INFORMATION. /// </summary> QueryLimitedInformation = 0x1000, /// <summary> /// Required to wait for the process to terminate using the wait functions. /// </summary> Synchronize = 0x100000 } [DllImport("ntdll.dll")] private static extern uint NtResumeProcess([In] IntPtr processHandle); [DllImport("ntdll.dll")] private static extern uint NtSuspendProcess([In] IntPtr processHandle); [DllImport("kernel32.dll", SetLastError = true)] private static extern IntPtr OpenProcess( ProcessAccess desiredAccess, bool inheritHandle, int processId); [DllImport("kernel32.dll", SetLastError = true)] [return: MarshalAs(UnmanagedType.Bool)] private static extern bool CloseHandle([In] IntPtr handle); public static void SuspendProcess(int processId) { IntPtr hProc = IntPtr.Zero; try { // Gets the handle to the Process hProc = OpenProcess(ProcessAccess.SuspendResume, false, processId); if (hProc != IntPtr.Zero) NtSuspendProcess(hProc); } finally { // Don't forget to close handle you created. if (hProc != IntPtr.Zero) CloseHandle(hProc); } } public static void ResumeProcess(int processId) { IntPtr hProc = IntPtr.Zero; try { // Gets the handle to the Process hProc = OpenProcess(ProcessAccess.SuspendResume, false, processId); if (hProc != IntPtr.Zero) NtResumeProcess(hProc); } finally { // Don't forget to close handle you created. if (hProc != IntPtr.Zero) CloseHandle(hProc); } } }
4、进程控制
我权且主进程为宿主，它通过Process类调用子进程，得其ID，以此为用。其调用代码为：
private void RunTestProcess(bool hidden = false) { string appPath = Path.GetDirectoryName(Application.ExecutablePath); string testAppPath = Path.Combine(appPath, "TestApp.exe"); var pi = new ProcessStartInfo(); pi.FileName = testAppPath; pi.Arguments = this.Handle.ToString(); pi.WindowStyle = hidden ? ProcessWindowStyle.Hidden : ProcessWindowStyle.Normal; this.childProcess = Process.Start(pi); txtInfo.Text = string.Format("子进程ID：{0}\r\n子进程名：{1}", childProcess.Id, childProcess.ProcessName); ... }
控制代码为：
private void btnWork_Click(object sender, EventArgs e) { if (this.childProcess == null || this.childProcess.HasExited) return; if ((int)btnWork.Tag == 0) { btnWork.Tag = 1; btnWork.Text = "恢复"; ProcessMgr.SuspendProcess(this.childProcess.Id); } else { btnWork.Tag = 0; btnWork.Text = "挂起"; ProcessMgr.ResumeProcess(this.childProcess.Id); } }
子进程以一定时器模拟其工作，向主进程抛进度消息：
private void timer_Tick(object sender, EventArgs e) { if (progressBar.Value < progressBar.Maximum) progressBar.Value += 1; else progressBar.Value = 0; if (this.hostHandle != IntPtr.Zero) SendMessage(this.hostHandle, WM_PROGRESS, 0, progressBar.Value); }
代码量就这么的少，简单吧……
5、效果图：
为示例，做了两个图，其一为显示子进程，其二为隐藏子进程。
实际项目调用独立进程模块，是以隐藏方式调用的，以宿主展示其处理进度，如此图：
后记：
扩展思路，一些优秀的开源工具，如youtube_dl、ffmpeg等，都以独立进程方式存在，且可通过CMD管道通信。
以此进程控制原理，可以基于这些开源工具做出相当不错的GUI工具出来。毕竟相对于强大的命令行，人们还是以简单操作为方便。
