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在.NET平台中，对C#提供了一个操作对本地和远程的访问进程,使能够启动和停止系统进程。这个类就是System.Diagnostics.Process，我们首先来了解一下该类。
一.解析System.Diagnostics.Process类
在C#中使用Process类可以提供对本地和远程的访问进程,使能够启动和停止系统进程，并且该类可以对系统进程进行管理。该类中的一些常用方法：Start() ，Kill()，WaitForExit()等方法；StartInfo，FileName，CreateNoWindow等属性。
1.Start()方法：启动（或重用）此 Process 组件的 StartInfo 属性指定的进程资源，并将其与该组件关联。如果启动了进程资源，则为 true；如果没有启动新的进程资源（例如，如果重用了现有进程），则为 false。
具体介绍一下该方法的实现代码：
/// <devdoc>
/// <para>
/// <see cref='System.Diagnostics.Process'/>如果过程资源被重用而不是启动，重用的进程与此相关联<see cref ='System.Diagnostics.Process'/>零件。
/// </para>
/// </devdoc>
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
public bool Start() {
Close();
ProcessStartInfo startInfo = StartInfo;
if (startInfo.FileName.Length == 0)
throw new InvalidOperationException(SR.GetString(SR.FileNameMissing));
if (startInfo.UseShellExecute) {
#if !FEATURE_PAL
return StartWithShellExecuteEx(startInfo);
#else
throw new InvalidOperationException(SR.GetString(SR.net_perm_invalid_val, "StartInfo.UseShellExecute", true));
#endif // !FEATURE_PAL
} else {
return StartWithCreateProcess(startInfo);
}
}
</div>
2.Kill()方法：立即停止关联的进程。Kill 强制终止进程，Kill 方法将异步执行。 在调用 Kill 方法后，请调用 WaitForExit 方法等待进程退出，或者检查 HasExited 属性以确定进程是否已经退出。
具体介绍一下该方法的实现代码：
[ResourceExposure(ResourceScope.Machine)]
[ResourceConsumption(ResourceScope.Machine)]
public void Kill() {
SafeProcessHandle handle = null;
try {
handle = GetProcessHandle(NativeMethods.PROCESS_TERMINATE);
if (!NativeMethods.TerminateProcess(handle, -1))
throw new Win32Exception();
}
finally {
ReleaseProcessHandle(handle);
}
}
</div>
SafeProcessHandle GetProcessHandle(int access) {
return GetProcessHandle(access, true);
}
/// <devdoc>
/// 获取进程的短期句柄，具有给定的访问权限。
///如果句柄存储在当前进程对象中，则使用它。
///注意，我们存储在当前进程对象中的句柄将具有我们需要的所有访问权限。
/// </devdoc>
/// <internalonly/>
[ResourceExposure(ResourceScope.None)]
[ResourceConsumption(ResourceScope.Machine, ResourceScope.Machine)]
SafeProcessHandle GetProcessHandle(int access, bool throwIfExited) {
Debug.WriteLineIf(processTracing.TraceVerbose, "GetProcessHandle(access = 0x" + access.ToString("X8", CultureInfo.InvariantCulture) + ", throwIfExited = " + throwIfExited + ")");
#if DEBUG
if (processTracing.TraceVerbose) {
StackFrame calledFrom = new StackTrace(true).GetFrame(0);
Debug.WriteLine(" called from " + calledFrom.GetFileName() + ", line " + calledFrom.GetFileLineNumber());
}
#endif
if (haveProcessHandle) {
if (throwIfExited) {
//因为hasProcessHandle是true，我们知道我们有进程句柄
//打开时至少要有SYNCHRONIZE访问，所以我们可以等待它
// zero timeout以查看进程是否已退出。
ProcessWaitHandle waitHandle = null;
try {
waitHandle = new ProcessWaitHandle(m_processHandle);
if (waitHandle.WaitOne(0, false)) {
if (haveProcessId)
throw new InvalidOperationException(SR.GetString(SR.ProcessHasExited, processId.ToString(CultureInfo.CurrentCulture)));
else
throw new InvalidOperationException(SR.GetString(SR.ProcessHasExitedNoId));
}
}
finally {
if( waitHandle != null) {
waitHandle.Close();
}
}
}
return m_processHandle;
}
else {
EnsureState(State.HaveId | State.IsLocal);
SafeProcessHandle handle = SafeProcessHandle.InvalidHandle;
#if !FEATURE_PAL
handle = ProcessManager.OpenProcess(processId, access, throwIfExited);
#else
IntPtr pseudohandle = NativeMethods.GetCurrentProcess();
// Get a real handle
if (!NativeMethods.DuplicateHandle (new HandleRef(this, pseudohandle),
new HandleRef(this, pseudohandle),
new HandleRef(this, pseudohandle),
out handle,
0,
false,
NativeMethods.DUPLICATE_SAME_ACCESS |
NativeMethods.DUPLICATE_CLOSE_SOURCE)) {
throw new Win32Exception();
}
#endif // !FEATURE_PAL
if (throwIfExited && (access & NativeMethods.PROCESS_QUERY_INFORMATION) != 0) {
if (NativeMethods.GetExitCodeProcess(handle, out exitCode) && exitCode != NativeMethods.STILL_ACTIVE) {
throw new InvalidOperationException(SR.GetString(SR.ProcessHasExited, processId.ToString(CultureInfo.CurrentCulture)));
}
}
return handle;
}
}
</div>
3.WaitForExit()方法：指示<see cref ='System.Diagnostics.Process'/>组件等待指定的毫秒数，以使相关联的进程退出。
具体介绍一下该方法的实现代码：
public bool WaitForExit(int milliseconds) {
SafeProcessHandle handle = null;
bool exited;
ProcessWaitHandle processWaitHandle = null;
try {
handle = GetProcessHandle(NativeMethods.SYNCHRONIZE, false);
if (handle.IsInvalid) {
exited = true;
}
else {
processWaitHandle = new ProcessWaitHandle(handle);
if( processWaitHandle.WaitOne(milliseconds, false)) {
exited = true;
signaled = true;
}
else {
exited = false;
signaled = false;
}
}
}
finally {
if( processWaitHandle != null) {
processWaitHandle.Close();
}
// If we have a hard timeout, we cannot wait for the streams
if( output != null && milliseconds == -1) {
output.WaitUtilEOF();
}
if( error != null && milliseconds == -1) {
error.WaitUtilEOF();
}
ReleaseProcessHandle(handle);
}
if (exited && watchForExit) {
RaiseOnExited();
}
return exited;
}
</div>
internal ProcessWaitHandle( SafeProcessHandle processHandle): base() {
SafeWaitHandle waitHandle = null;
bool succeeded = NativeMethods.DuplicateHandle(
new HandleRef(this, NativeMethods.GetCurrentProcess()),
processHandle,
new HandleRef(this, NativeMethods.GetCurrentProcess()),
out waitHandle,
0,
false,
NativeMethods.DUPLICATE_SAME_ACCESS);
if (!succeeded) {
Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
}