java - 如何终止进程树？

Question

我正在使用 Runtime.getRuntime().exec() 命令来启动一个批处理文件，该批处理文件又会为 Windows 平台启动另一个进程。

javaw.exe(Process1)
 |___xyz.bat(Process2)
        |___javaw.exe(Process3)

Runtime.getRuntime().exec() 返回一个 Process 对象，它有一个 destroy 方法，但是当我使用 destroy() ，它只会杀死 xyz.bat 并使批处理文件的子进程悬空。

是否有一种干净的方法来销毁以批处理为根的进程树？

郑重声明，我不能使用任何自定义库来删除批处理文件来绕过这个问题。

Answer 1

使用标准 Java API 是不可能的(请参阅帖子末尾的编辑以获取更改此内容的更新)。您将需要一些 native 代码。使用 JNA，我使用了如下代码:

public class Win32Process
{
    WinNT.HANDLE handle;
    int pid;

    Win32Process (int pid) throws IOException
    {
        handle = Kernel32.INSTANCE.OpenProcess ( 
                0x0400| /* PROCESS_QUERY_INFORMATION */
                0x0800| /* PROCESS_SUSPEND_RESUME */
                0x0001| /* PROCESS_TERMINATE */
                0x00100000 /* SYNCHRONIZE */,
                false,
                pid);
        if (handle == null) 
            throw new IOException ("OpenProcess failed: " + 
                    Kernel32Util.formatMessageFromLastErrorCode (Kernel32.INSTANCE.GetLastError ()));
        this.pid = pid;
    }

    @Override
    protected void finalize () throws Throwable
    {
        Kernel32.INSTANCE.CloseHandle (handle);
    }

    public void terminate ()
    {
        Kernel32.INSTANCE.TerminateProcess (handle, 0);
    }

    public List<Win32Process> getChildren () throws IOException
    {
        ArrayList<Win32Process> result = new ArrayList<Win32Process> ();
        WinNT.HANDLE hSnap = KernelExtra.INSTANCE.CreateToolhelp32Snapshot (KernelExtra.TH32CS_SNAPPROCESS, new DWORD(0));
        KernelExtra.PROCESSENTRY32.ByReference ent = new KernelExtra.PROCESSENTRY32.ByReference ();
        if (!KernelExtra.INSTANCE.Process32First (hSnap, ent)) return result;
        do {
            if (ent.th32ParentProcessID.intValue () == pid) result.add (new Win32Process (ent.th32ProcessID.intValue ()));
        } while (KernelExtra.INSTANCE.Process32Next (hSnap, ent));
        Kernel32.INSTANCE.CloseHandle (hSnap);
        return result;
    }

此代码使用标准 JNA 库中未包含的以下 JNA 声明:

public interface KernelExtra extends StdCallLibrary {

    /**
     * Includes all heaps of the process specified in th32ProcessID in the snapshot. To enumerate the heaps, see
     * Heap32ListFirst.
     */
    WinDef.DWORD TH32CS_SNAPHEAPLIST = new WinDef.DWORD(0x00000001);

    /**
     * Includes all processes in the system in the snapshot. To enumerate the processes, see Process32First.
     */
    WinDef.DWORD TH32CS_SNAPPROCESS  = new WinDef.DWORD(0x00000002);

    /**
     * Includes all threads in the system in the snapshot. To enumerate the threads, see Thread32First.
     */
    WinDef.DWORD TH32CS_SNAPTHREAD   = new WinDef.DWORD(0x00000004);

    /**
     * Includes all modules of the process specified in th32ProcessID in the snapshot. To enumerate the modules, see
     * Module32First. If the function fails with ERROR_BAD_LENGTH, retry the function until it succeeds.
     */
    WinDef.DWORD TH32CS_SNAPMODULE   = new WinDef.DWORD(0x00000008);

    /**
     * Includes all 32-bit modules of the process specified in th32ProcessID in the snapshot when called from a 64-bit
     * process. This flag can be combined with TH32CS_SNAPMODULE or TH32CS_SNAPALL. If the function fails with
     * ERROR_BAD_LENGTH, retry the function until it succeeds.
     */
    WinDef.DWORD TH32CS_SNAPMODULE32 = new WinDef.DWORD(0x00000010);

    /**
     * Includes all processes and threads in the system, plus the heaps and modules of the process specified in th32ProcessID.
     */
    WinDef.DWORD TH32CS_SNAPALL      = new WinDef.DWORD((TH32CS_SNAPHEAPLIST.intValue() |
            TH32CS_SNAPPROCESS.intValue() | TH32CS_SNAPTHREAD.intValue() | TH32CS_SNAPMODULE.intValue()));

    /**
     * Indicates that the snapshot handle is to be inheritable.
     */
    WinDef.DWORD TH32CS_INHERIT      = new WinDef.DWORD(0x80000000);

    /**
     * Describes an entry from a list of the processes residing in the system address space when a snapshot was taken.
     */
    public static class PROCESSENTRY32 extends Structure {

        public static class ByReference extends PROCESSENTRY32 implements Structure.ByReference {
            public ByReference() {
            }

            public ByReference(Pointer memory) {
                super(memory);
            }
        }

        public PROCESSENTRY32() {
            dwSize = new WinDef.DWORD(size());
        }

        public PROCESSENTRY32(Pointer memory) {
            useMemory(memory);
            read();
        }

        /**
         * The size of the structure, in bytes. Before calling the Process32First function, set this member to
         * sizeof(PROCESSENTRY32). If you do not initialize dwSize, Process32First fails.
         */
        public WinDef.DWORD dwSize;

        /**
         * This member is no longer used and is always set to zero.
         */
        public WinDef.DWORD cntUsage;

        /**
         * The process identifier.
         */
        public WinDef.DWORD th32ProcessID;

        /**
         * This member is no longer used and is always set to zero.
         */
        public BaseTSD.ULONG_PTR th32DefaultHeapID;

        /**
         * This member is no longer used and is always set to zero.
         */
        public WinDef.DWORD th32ModuleID;

        /**
         * The number of execution threads started by the process.
         */
        public WinDef.DWORD cntThreads;

        /**
         * The identifier of the process that created this process (its parent process).
         */
        public WinDef.DWORD th32ParentProcessID;

        /**
         * The base priority of any threads created by this process.
         */
        public WinDef.LONG pcPriClassBase;

        /**
         * This member is no longer used, and is always set to zero.
         */
        public WinDef.DWORD dwFlags;

        /**
         * The name of the executable file for the process. To retrieve the full path to the executable file, call the
         * Module32First function and check the szExePath member of the MODULEENTRY32 structure that is returned.
         * However, if the calling process is a 32-bit process, you must call the QueryFullProcessImageName function to
         * retrieve the full path of the executable file for a 64-bit process.
         */
        public char[] szExeFile = new char[WinDef.MAX_PATH];
    }


    // the following methods are in kernel32.dll, but not declared there in the current version of Kernel32:

    /**
     * Takes a snapshot of the specified processes, as well as the heaps, modules, and threads used by these processes.
     *  
     * @param dwFlags
     *   The portions of the system to be included in the snapshot.
     * 
     * @param th32ProcessID
     *   The process identifier of the process to be included in the snapshot. This parameter can be zero to indicate
     *   the current process. This parameter is used when the TH32CS_SNAPHEAPLIST, TH32CS_SNAPMODULE,
     *   TH32CS_SNAPMODULE32, or TH32CS_SNAPALL value is specified. Otherwise, it is ignored and all processes are
     *   included in the snapshot.
     *
     *   If the specified process is the Idle process or one of the CSRSS processes, this function fails and the last
     *   error code is ERROR_ACCESS_DENIED because their access restrictions prevent user-level code from opening them.
     *
     *   If the specified process is a 64-bit process and the caller is a 32-bit process, this function fails and the
     *   last error code is ERROR_PARTIAL_COPY (299).
     *
     * @return
     *   If the function succeeds, it returns an open handle to the specified snapshot.
     *
     *   If the function fails, it returns INVALID_HANDLE_VALUE. To get extended error information, call GetLastError.
     *   Possible error codes include ERROR_BAD_LENGTH.
     */
    public WinNT.HANDLE CreateToolhelp32Snapshot(WinDef.DWORD dwFlags, WinDef.DWORD th32ProcessID);

    /**
     * Retrieves information about the first process encountered in a system snapshot.
     *
     * @param hSnapshot A handle to the snapshot returned from a previous call to the CreateToolhelp32Snapshot function.
     * @param lppe A pointer to a PROCESSENTRY32 structure. It contains process information such as the name of the
     *   executable file, the process identifier, and the process identifier of the parent process.
     * @return
     *   Returns TRUE if the first entry of the process list has been copied to the buffer or FALSE otherwise. The
     *   ERROR_NO_MORE_FILES error value is returned by the GetLastError function if no processes exist or the snapshot
     *   does not contain process information.
     */
    public boolean Process32First(WinNT.HANDLE hSnapshot, KernelExtra.PROCESSENTRY32.ByReference lppe);

    /**
     * Retrieves information about the next process recorded in a system snapshot.
     *
     * @param hSnapshot A handle to the snapshot returned from a previous call to the CreateToolhelp32Snapshot function.
     * @param lppe A pointer to a PROCESSENTRY32 structure.
     * @return
     *   Returns TRUE if the next entry of the process list has been copied to the buffer or FALSE otherwise. The
     *   ERROR_NO_MORE_FILES error value is returned by the GetLastError function if no processes exist or the snapshot
     *   does not contain process information.
     */
    public boolean Process32Next(WinNT.HANDLE hSnapshot, KernelExtra.PROCESSENTRY32.ByReference lppe);


}

然后您可以使用“getChildren()”方法获取子项列表，终止父项，然后递归地终止子项。

我相信您可以使用反射来增加 java.lang.Process 的 PID(不过，我还没有这样做；我转而使用 Win32 API 自己创建进程，这样我就可以更好地控制它) .

所以把它放在一起，你需要这样的东西:

int pid = (some code to extract PID from the process you want to kill);
Win32Process process = new Win32Process(pid);
kill(process);

public void kill(Win32Process target) throws IOException
{
   List<Win32Process> children = target.getChildren ();
   target.terminateProcess ();
   for (Win32Process child : children) kill(child);
}

编辑

事实证明，Java API 的这一特殊缺点已在 Java 9 中得到修复。请参阅 Java 9 文档的预览 here (如果没有加载正确的页面，您需要查看 java.lang.ProcessHandle 接口(interface))。对于上述问题的要求，代码现在看起来像这样:

Process child = ...;
kill (child.toHandle());

public void kill (ProcessHandle handle)
{
    handle.descendants().forEach((child) -> kill(child));
    handle.destroy();
}

(请注意，这还没有经过测试——我还没有切换到 Java 9，但正在积极阅读它)