最近在用java写监视文件系统的东东,特对C++和Java下的不同实现方法做一小结。
1.Java环境下
很多人都说用文件轮询HashTable,然后如何如何比较,这种方法效率极为低下,还会造成无谓的磁盘读写。好了JDK 7中提供了java.nio.file大家可以通过 WatchService 来实现对文件的事件的监听。千万记得在JDK 7下哈,现在的JDK7的预览版发布到 jdk-7-ea-bin-b84-windows-i586-18_feb_2010.exe了。有兴趣的哥们可以把这个程序拿下去学习学习。
该段代码来自于 Sun(准确的该说是Oracle了) http://java.sun.com/docs/books/tutorial/essential/io/notification.html
/* * Copyright 2008-2009 Sun Microsystems, Inc. All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Sun Microsystems nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ import java.nio.file.*; import static java.nio.file.StandardWatchEventKind.*; import static java.nio.file.LinkOption.*; import java.nio.file.attribute.*; import java.io.*; import java.util.*; /** * Example to watch a directory (or tree) for changes to files. */ public class WatchDir { private final WatchService watcher; private final Map<WatchKey,Path> keys; private final boolean recursive; private boolean trace = false; @SuppressWarnings("unchecked") static <T> WatchEvent<T> cast(WatchEvent<?> event) { return (WatchEvent<T>)event; } /** * Register the given directory with the WatchService */ private void register(Path dir) throws IOException { WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY); if (trace) { FileRef prev = keys.get(key); if (prev == null) { System.out.format("register: %s/n", dir); } else { if (!dir.equals(prev)) { System.out.format("update: %s -> %s/n", prev, dir); } } } keys.put(key, dir); } /** * Register the given directory, and all its sub-directories, with the * WatchService. */ private void registerAll(final Path start) throws IOException { // register directory and sub-directories Files.walkFileTree(start, new SimpleFileVisitor<Path>() { @Override public FileVisitResult preVisitDirectory(Path dir) { try { register(dir); } catch (IOException x) { throw new IOError(x); } return FileVisitResult.CONTINUE; } }); } /** * Creates a WatchService and registers the given directory */ WatchDir(Path dir, boolean recursive) throws IOException { this.watcher = FileSystems.getDefault().newWatchService(); this.keys = new HashMap<WatchKey,Path>(); this.recursive = recursive; if (recursive) { System.out.format("Scanning %s .../n", dir); registerAll(dir); System.out.println("Done."); } else { register(dir); } // enable trace after initial registration this.trace = true; } /** * Process all events for keys queued to the watcher */ void processEvents() { for (;;) { // wait for key to be signalled WatchKey key; try { key = watcher.take(); } catch (InterruptedException x) { return; } Path dir = keys.get(key); if (dir == null) { System.err.println("WatchKey not recognized!!"); continue; } for (WatchEvent<?> event: key.pollEvents()) { WatchEvent.Kind kind = event.kind(); // TBD - provide example of how OVERFLOW event is handled if (kind == OVERFLOW) { continue; } // Context for directory entry event is the file name of entry WatchEvent<Path> ev = cast(event); Path name = ev.context(); Path child = dir.resolve(name); // print out event System.out.format("%s: %s/n", event.kind().name(), child); // if directory is created, and watching recursively, then // register it and its sub-directories if (recursive && (kind == ENTRY_CREATE)) { try { if (Attributes.readBasicFileAttributes(child, NOFOLLOW_LINKS).isDirectory()) { registerAll(child); } } catch (IOException x) { // ignore to keep sample readbale } } } // reset key and remove from set if directory no longer accessible boolean valid = key.reset(); if (!valid) { keys.remove(key); // all directories are inaccessible if (keys.isEmpty()) { break; } } } } static void usage() { System.err.println("usage: java WatchDir [-r] dir"); System.exit(-1); } public static void main(String[] args) throws IOException { // parse arguments if (args.length == 0 || args.length > 2) usage(); boolean recursive = false; int dirArg = 0; if (args[0].equals("-r")) { if (args.length < 2) usage(); recursive = true; dirArg++; } // register directory and process its events Path dir = Paths.get(args[dirArg]); new WatchDir(dir, recursive).processEvents(); } }
2.C++环境下
其实从操作系统层面能够监听到文件操作事件是最好的了。
在windows环境下呢可以通过用拷贝钩子实现对文件夹的监控。
可参考网页 http://ccrun.com/article.asp?i=601&d=0z20f4
ICopyHook是一个用于创建拷贝钩子处理程序COM接口,它决定一个文件夹或者打印机对象是否可以被移动,拷贝,重命名或删除。Shell在执行这些操作之前,会调用ICopyHook接口的CopyCallback方法对它们进行验证。CopyCallback返回一个int值指示Shell是否应该继续执行这个操作。返回值IDYES表示继续,而返回值IDNO和IDCANCEL则表示终止。
一个文件夹对象可以安装多个拷贝钩子处理程序。如果出现这种情况,Shell会依次调用每个处理程序。只有当每个处理程序都返回IDYES时,Shell才真正执行用户请求的操作。
拷贝钩子处理程序的作用是在上述四种操作执行前对它们进行验证,但是Shell并不会把操作的结果通知给拷贝钩子处理程序。而windows提供的API函数FindFirstChangeNotification和FindNextChangeNotification却可以实现这个功能。因此,只有把这种两种方法结合起来,才能对一个文件夹的状态进行完全的监控。
拷贝钩子处理程序实现并不困难,首先创建一个作为进程内组件的COM对象,它只需要暴露一个ICopyHook接口(当然还有IUnknown)。然后用regsrv32.exe注册这个COM组件。最后一步是向Shell注册你的这个拷贝钩子处理程序,方法是在注册表HKEY_CLASSES_ROOT/Directory/Shellex/CopyHookHandlers下创建一个名称任意的sub key,在此sub key中创建一个类型为REG_SZ的项并将你的COM对象的CLSID作为它的默认值就可以了。
下面就是一个拷贝钩子的实现程序(注:以下代码经老妖改动并添加了详细操作过程,在BCB6中成功编译并通过测试)
2.1. 从ICopyHook接口创建TCopyHook,从IClassFactory接口创建TClassFactory:
// TCopyHook.h
// TCopyHook类实现了ICopyHook接口,TClassFactory实现了IClassFactory接口
//---------------------------------------------------------------------------
#define NO_WIN32_LEAN_AND_MEAN
#include <shlobj.h>
//---------------------------------------------------------------------------
class TCopyHook: public ICopyHook
{
public:
TCopyHook():m_refcnt(0) {}
STDMETHODIMP QueryInterface(REFIID iid,void **ppvObject);
STDMETHODIMP_(ULONG) AddRef();
STDMETHODIMP_(ULONG) Release();
STDMETHODIMP_(UINT) CopyCallback(HWND hwnd, UINT wFunc, UINT wFlags,
LPCTSTR pszSrcFile, DWORD dwSrcAttribs,
LPCTSTR pszDestFile, DWORD dwDestAttribs);
private:
int m_refcnt;
};
//---------------------------------------------------------------------------
class TClassFactory : public IClassFactory
{
public:
TClassFactory():m_refcnt(0) {}
STDMETHODIMP QueryInterface(REFIID iid, void **ppvObject);
STDMETHODIMP_(ULONG) AddRef();
STDMETHODIMP_(ULONG) Release();
STDMETHODIMP CreateInstance(IUnknown *pUnkOuter, REFIID riid, void **ppvObject);
STDMETHODIMP LockServer(BOOL fLock);
private:
int m_refcnt;
};
// TCopyHook.cpp
// TCopyHook对象和TClassFactory对象的实现文件
#include <stdio.h>
#include "TCopyHook.h"
//---------------------------------------------------------------------------
extern LONG nLocks; // 对象计数,用于DllCanUnloadNow
ULONG __stdcall TCopyHook::AddRef()
{
if(m_refcnt == 0)
nLocks++;
m_refcnt++;
return m_refcnt;
}
//---------------------------------------------------------------------------
ULONG __stdcall TCopyHook::Release()
{
int nNewCnt = --m_refcnt;
if(nNewCnt <= 0)
{
nLocks--;
delete this;
}
return nNewCnt;
}
//---------------------------------------------------------------------------
HRESULT __stdcall TCopyHook::QueryInterface(REFIID dwIID, void **ppvObject)
{
if(dwIID == IID_IUnknown)
*ppvObject = static_cast<IUnknown*>(this);
else
if(dwIID == IID_IShellCopyHook)
*ppvObject = static_cast<ICopyHook*>(this);
else
return E_NOINTERFACE;
reinterpret_cast<IUnknown*>(*ppvObject)->AddRef();
return S_OK;
}
//---------------------------------------------------------------------------
// 这就是CopyCallback方法,拷贝钩子的所有功能由它实现。参数的具体值参看MSDN
UINT __stdcall TCopyHook::CopyCallback(HWND hwnd, UINT wFunc, UINT wFlags,
LPCTSTR pszSrcFile, DWORD dwSrcAttribs,
LPCTSTR pszDestFile, DWORD dwDestAttribs)
{
char szMessage[MAX_PATH+14];
sprintf(szMessage, "对%s进行的操作,是否继续?", pszSrcFile);
return MessageBox(NULL, szMessage, "确认", MB_YESNO | MB_ICONEXCLAMATION);
}
//---------------------------------------------------------------------------
ULONG __stdcall TClassFactory::AddRef()
{
if(m_refcnt==0)
nLocks++;
m_refcnt++;
return m_refcnt;
}
//---------------------------------------------------------------------------
ULONG __stdcall TClassFactory::Release()
{
int nNewCnt = --m_refcnt;
if(nNewCnt <= 0)
{
nLocks--;
delete this;
}
return nNewCnt;
}
//---------------------------------------------------------------------------
HRESULT __stdcall TClassFactory::QueryInterface(REFIID dwIID, void **ppvObject)
{
if(dwIID == IID_IUnknown)
*ppvObject = static_cast<IUnknown*>(this);
else
if(dwIID == IID_IClassFactory)
*ppvObject = static_cast<IClassFactory*>(this);
else
return E_NOINTERFACE;
reinterpret_cast<IUnknown*>(*ppvObject)->AddRef();
return S_OK;
}
//---------------------------------------------------------------------------
HRESULT __stdcall TClassFactory::CreateInstance(IUnknown* pUnkownOuter,
REFIID riid, void** ppvObj)
{
if(pUnkownOuter != NULL)
return CLASS_E_NOAGGREGATION;
TCopyHook *pObj = new TCopyHook;
pObj->AddRef();
HRESULT hr = pObj->QueryInterface(riid, ppvObj);
pObj->Release();
return hr;
}
//---------------------------------------------------------------------------
HRESULT __stdcall TClassFactory::LockServer(BOOL fLock)
{
if(fLock)
nLocks++;
else
nLocks--;
return S_OK;
}
2.2. 在BCB中New-->ActiveX-->ActiveX Library,然后添加相应代码。
//----------------------------------------------------------------
// 原作: webber84
// 本文转自 C++Builder研究 - http://www.ccrun.com/article.asp?i=601&d=0z20f4
// 修改: ccrun(老妖)(www.ccrun.com)
// 欢迎访问C++ Builder 研究:http://www.ccrun.com
// 为防不负责任的转载者,此处加上原作者及修改者信息,请见谅。
//----------------------------------------------------------------
以下是修改后的Project1.cpp,大家可以直接copy过去。:
//$$---- axlib proj source ---- (stAXLibProjectSource)
#define NO_WIN32_LEAN_AND_MEAN
#include <vcl.h>
#pragma hdrstop
#include <atl/atlvcl.h>
#include <objbase.h>
#include <olectl.h>
#include "TCopyHook.h"
#pragma package(smart_init)
TComModule Project1Module;
TComModule &_Module = Project1Module;
// 这是要添加到注册表中的项,注意如果你要使用这段代码,应该用UUIDGEN.exe生成一
// 个新的CLSID。
const char* szRegTable[][3]=
{
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}", 0, "CopyHook"},
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}//InProcServer32", 0, (const char*)-1},
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}//InProcServer32", "ThreadingModel", "Apartment"},
{"CLSID//{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}//ProgID", 0, "webber84.CopyHook.1"},
{"webber84.CopyHook.1", 0, "CopyHook"},
{"webber84.CopyHook.1//CLSID", 0, "{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735}"}
};
HMODULE hInstance = NULL;
LONG nLocks = 0;
//---------------------------------------------------------------------------
// The ATL Object map holds an array of _ATL_OBJMAP_ENTRY structures that
// described the objects of your OLE server. The MAP is handed to your
// project's CComModule-derived _Module object via the Init method.
BEGIN_OBJECT_MAP(ObjectMap)
END_OBJECT_MAP()
//---------------------------------------------------------------------------
// Entry point of your Server invoked by Windows for processes or threads are
// initialized or terminated.
int WINAPI DllEntryPoint(HINSTANCE hinst, unsigned long reason, void*)
{
if(reason == DLL_PROCESS_ATTACH)
hInstance = (HMODULE)hinst;
return TRUE;
}
//---------------------------------------------------------------------------
// _Module.Term is typically invoked from the DLL_PROCESS_DETACH of your
// DllEntryPoint. However, this may result in an incorrect shutdown sequence.
// Instead an Exit routine is setup to invoke the cleanup routine
// CComModule::Term.
void ModuleTerm(void)
{
_Module.Term();
}
#pragma exit ModuleTerm 63
//---------------------------------------------------------------------------
// Entry point of your Server invoked to inquire whether the DLL is no
// longer in use and should be unloaded.
STDAPI __export DllCanUnloadNow(void)
{
return nLocks == 0? S_OK: S_FALSE;
}
//---------------------------------------------------------------------------
// Entry point of your Server allowing OLE to retrieve a class object from
// your Server
STDAPI __export DllGetClassObject(REFCLSID rclsid, REFIID riid, LPVOID* ppv)
{
HRESULT hr = E_OUTOFMEMORY;
*ppv = NULL;
TClassFactory *pClassFactory = new TClassFactory;
if(pClassFactory != NULL)
hr = pClassFactory->QueryInterface(riid, ppv);
return hr;
}
//---------------------------------------------------------------------------
// Entry point of your Server invoked to instruct the server to create
// registry entries for all classes supported by the module
STDAPI __export DllRegisterServer(void)
{
HRESULT hr = S_OK;
int nItems = sizeof(szRegTable) / sizeof(szRegTable[0]);
char szDllPath[MAX_PATH];
GetModuleFileName(hInstance, szDllPath, MAX_PATH);
for(int i=0; i<nItems && SUCCEEDED(hr); i++)
{
const char *szKeyName = szRegTable[i][0];
const char *szValueName = szRegTable[i][1];
const char *szValue = szRegTable[i][2];
if(szValue == (const char*) - 1)
szValue = szDllPath;
HKEY hKey;
LONG lReturn = RegCreateKey(HKEY_CLASSES_ROOT, szKeyName, &hKey);
if(lReturn == ERROR_SUCCESS)
{
RegSetValueEx(hKey, szValueName, 0, REG_SZ,
(const BYTE*)szValue, strlen(szValue)+1);
RegCloseKey(hKey);
}
if(lReturn != ERROR_SUCCESS)
{
hr = SELFREG_E_CLASS;
DllUnregisterServer();
}
}
return hr;
}
//---------------------------------------------------------------------------
// Entry point of your Server invoked to instruct the server to remove
// all registry entries created through DllRegisterServer.
STDAPI __export DllUnregisterServer(void)
{
HRESULT hr = S_OK;
LONG lReturn = 0;
int nItems = sizeof(szRegTable) / sizeof(szRegTable[0]);
for(int i=nItems-1; i>=0; i--)
{
const char *szKeyName = szRegTable[i][0];
if((i == nItems-1) || stricmp(szRegTable[i+1][0], szKeyName) != 0)
lReturn = RegDeleteKey(HKEY_CLASSES_ROOT, szKeyName);
if(lReturn != ERROR_SUCCESS)
hr = SELFREG_E_CLASS;
}
return hr;
}
//---------------------------------------------------------------------------
2.3. 在BCB的IDE环境中,选择菜单的Project-->Add to Project-->找到刚才创建的TCopyHook.cpp-->OK
编译工程。如果没有错误,将生成Project1.dll。
2.4. 修改注册表:
在HKEY_CLASSES_ROOT/Directory/shellex/CopyHookHandlers/下新建一个项,命名为Test,更改其默认值为{7e10a039-fe03-4f9c-b7e1-c5eeeaf53735},老妖注:这里的默认值应该和project1.cpp中的相同注册项目相同。
2.5. 注册COM组件:
运行regsvr32.exe 路径/project.dll,点击确定后不要理会再弹出的错误窗口。重新启动计算机,试着copy一个文件夹,当paste的时候,效果出来了,嘿嘿。自己试试吧。
源代码下载:
http://www.ccrun.com/cctools/MyCopyHook.rar
在Linux环境下呢可以通过用inotify 监视文件系统的变化。
可参考网页 http://blog.csdn.net/rstevens/archive/2008/05/12/2438567.aspx
可以用 Linux 2.6 kenel 提供的 inotify 机制来监控文件系统的变化,例如增加文件,删除文件,修改文件等
下面是一个例子程序,可用来监控一个目录,如果在此目录下进行创建文件、删除文件、修改文件的操作,会有提示信息打印到屏幕上
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![](http://images.csdn.net/syntaxhighlighting/OutliningIndicators/None.gif)
3.小结
无论哪种语言和方法,都是借助系统级的事件通知来完成对文件系统的监视的,性能上自然很强了。