C#启动一个外部程序(3)CreateProcess

今天还是继续说说C#调用系统Api启动外部程序的方法，今天要说的是CreateProcess这个Api函数，相比前两篇文章(一、二)中所说的Api，CreateProcess参数要更复杂一些，但使用起来，要更灵活。
1.

using System.Runtime.InteropServices;

2. CreateProcess中用到了几个结构体类型，先声明他们：

        [System.Runtime.InteropServices.StructLayout(LayoutKind.Sequential)]
        public class SECURITY_ATTRIBUTES
        {
            public int nLength;
            public string lpSecurityDescriptor;
            public bool bInheritHandle;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct STARTUPINFO
        {
            public int cb;
            public string lpReserved;
            public string lpDesktop;
            public int lpTitle;
            public int dwX;
            public int dwY;
            public int dwXSize;
            public int dwYSize;
            public int dwXCountChars;
            public int dwYCountChars;
            public int dwFillAttribute;
            public int dwFlags;
            public int wShowWindow;
            public int cbReserved2;
            public byte lpReserved2;
            public IntPtr hStdInput;
            public IntPtr hStdOutput;
            public IntPtr hStdError;
        }

        [StructLayout(LayoutKind.Sequential)]
        public struct PROCESS_INFORMATION
        {
            public IntPtr hProcess;
            public IntPtr hThread;
            public int dwProcessId;
            public int dwThreadId;
        }

3. 声明CreateProcess

        [DllImport("Kernel32.dll", CharSet = CharSet.Ansi)]
        public static extern bool CreateProcess(
            StringBuilder lpApplicationName, StringBuilder lpCommandLine,
            SECURITY_ATTRIBUTES lpProcessAttributes,
            SECURITY_ATTRIBUTES lpThreadAttributes,
            bool bInheritHandles,
            int dwCreationFlags,
            StringBuilder lpEnvironment,
            StringBuilder lpCurrentDirectory,
            ref STARTUPINFO lpStartupInfo,
            ref PROCESS_INFORMATION lpProcessInformation
            );

4. 下边这三个也是Api，作用看注释

        #region Win32 Api : WaitForSingleObject
        //检测一个系统核心对象(线程，事件，信号)的信号状态，当对象执行时间超过dwMilliseconds就返回，否则就一直等待对象返回信号
        [DllImport("Kernel32.dll")]
        public static extern uint WaitForSingleObject(System.IntPtr hHandle, uint dwMilliseconds);

        #endregion

        #region Win32 Api : CloseHandle
        //关闭一个内核对象,释放对象占有的系统资源。其中包括文件、文件映射、进程、线程、安全和同步对象等
        [DllImport("Kernel32.dll")]
        public static extern bool CloseHandle(System.IntPtr hObject);

        #endregion       

        #region Win32 Api : GetExitCodeProcess
        //获取一个已中断进程的退出代码,非零表示成功，零表示失败。
        //参数hProcess，想获取退出代码的一个进程的句柄，参数lpExitCode，用于装载进程退出代码的一个长整数变量。
        [DllImport("Kernel32.dll")]
        static extern bool GetExitCodeProcess(System.IntPtr hProcess, ref uint lpExitCode);

        #endregion

5. 如果示例中argm指定的程序执行时间很长，进程会被阻塞到WaitForSingleObject行处，直到命令执行完毕或进程被中止才继续执行后边的语句。

            string argm = "cmd.exe";

            STARTUPINFO sInfo = new STARTUPINFO();
            PROCESS_INFORMATION pInfo = new PROCESS_INFORMATION();

            if (!CreateProcess(null, new StringBuilder(argm), null, null, false, 0, null, null, ref sInfo, ref pInfo))
            {
                throw new Exception("调用失败");
            }
            uint i = 0;
            WaitForSingleObject(pInfo.hProcess, int.MaxValue);            
            GetExitCodeProcess(pInfo.hProcess, ref i);
            CloseHandle(pInfo.hProcess);
            CloseHandle(pInfo.hThread);