目录监视java中的更改
我正在使用WatchService监视目录中的更改，特别是在目录中创建新文件。以下是我的密码-目录监视java中的更改,java,nio,Java,Nio,我正在使用WatchService监视目录中的更改，特别是在目录中创建新文件。以下是我的密码- package watcher; import java.nio.file.*; import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE; import static java.nio.file.StandardWatchEventKinds.OVERFLOW; import java.io.*; public class
package watcher;
import java.nio.file.*;
import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
import static java.nio.file.StandardWatchEventKinds.OVERFLOW;
import java.io.*;
public class Watch {
public static void main(String[] args) throws IOException {
Path dir = Paths.get("c:\\mk\\");
WatchService service = FileSystems.getDefault().newWatchService();
WatchKey key = dir.register(service, ENTRY_CREATE);
System.out.println("Watching directory: "+dir.toString());
for(;;){
WatchKey key1;
try {
key1 = service.take();
} catch (InterruptedException x) {
break;
}
for (WatchEvent<?> event: key1.pollEvents()) {
WatchEvent.Kind<?> kind = event.kind();
if (kind == OVERFLOW) {
continue;
}
WatchEvent<Path> ev = (WatchEvent<Path>)event;
Path filename = ev.context();
Path child = dir.resolve(filename);
System.out.println("New file: "+child.toString()+" created.");
try{
FileInputStream in = new FileInputStream(child.toFile());
System.out.println("File opened for reading");
in.close();
System.out.println("File Closed");
}catch(Exception x){
x.printStackTrace();
}
}
boolean valid = key.reset();
if (!valid) {
break;
}
}
}
}
packagewatcher；
导入java.nio.file.*；
导入静态java.nio.file.StandardWatchEventTypes.ENTRY\u创建；
导入静态java.nio.file.StandardWatchEventTypes.OVERFLOW；
导入java.io.*；
公共班级值班{
公共静态void main（字符串[]args）引发IOException{
Path dir=Path.get（“c:\\mk\\”；
WatchService=FileSystems.getDefault（）.newWatchService（）；
WatchKey=dir.register（服务、条目和创建）；
System.out.println（“监视目录：+dir.toString（））；
对于（；；）{
手表按键1；
试一试{
key1=service.take（）；
}捕捉（中断异常x）{
打破
}
for（WatchEvent事件：key1.pollEvents（））{
WatchEvent.Kind-Kind=event.Kind（）；
如果（种类==溢出）{
继续；
}
WatchEvent ev=（WatchEvent）事件；
路径文件名=ev.context（）；
Path child=dir.resolve（文件名）；
System.out.println（“新文件：“+child.toString（）+”已创建”）；
试一试{
FileInputStream in=新的FileInputStream（child.toFile（））；
System.out.println（“打开读取的文件”）；
in.close（）；
System.out.println（“文件关闭”）；
}捕获（异常x）{
x、 printStackTrace（）；
}
}
布尔有效值=key.reset（）；
如果（！有效）{
打破
}
}
}
}
Watching directory: c:\mk
New file: c:\mk\New Text Document (2).txt created.
File opened for reading
File Closed
New file: c:\mk\Config.class created.
java.io.FileNotFoundException: c:\mk\Config.class (The process cannot access the file because it is being used by another process)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at watcher.Watch.main(Watch.java:36)
New file: c:\mk\New Text Document (3).txt created.
File opened for reading
File Closed
监视目录：c:\mk
新文件：c:\mk\New Text Document（2）.txt已创建。
文件已打开以供读取
文件关闭
新文件：c:\mk\Config.class已创建。
java.io.FileNotFoundException:c:\mk\Config.class（该进程无法访问该文件，因为它正被另一个进程使用）
在java.io.FileInputStream.open（本机方法）
位于java.io.FileInputStream。（FileInputStream.java:138）
at watcher.Watch.main（Watch.java:36）
新文件：c:\mk\New Text Document（3）.txt已创建。
文件已打开以供读取
文件关闭
新文本文档（2.txt）新文本文档（3.txt）Config.class请在这方面帮助我。我通过实现算法实现了这一点：Watcher线程将文件名放入BlockingQueue，其他线程将轮询此队列，获取文件名，尝试几次打开文件。若文件被打开，Windows Copier已释放文件锁，我们可以继续。所以，当其他线程发现文件已解锁时，其他线程将把该文件名放入已处理队列，我的应用程序将从中检索文件名。另外一个线程在通过打开文件检查文件解锁时，如果解锁文件运行很长时间，我们可以将此文件名放回BlockingQueue并处理其他文件名，前者可以稍后处理 解决方案：希望这对其他人有所帮助：
package dirwatch;
import java.nio.file.*;
import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
import static java.nio.file.StandardWatchEventKinds.OVERFLOW;
import static java.nio.file.LinkOption.*;
import java.nio.file.attribute.*;
import java.io.*;
import java.util.*;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;
public class WatchDir {
private final WatchService watcher;
private final Map<WatchKey,Path> keys;
private final boolean recursive;
private boolean trace = false;
private BlockingQueue<String> fileProcessingQueue;
//******* processedFileQueue **** will be used by other threads to retrive unlocked files.. so I have
// kept as public final
public final BlockingQueue<String> processedFileQueue;
private volatile boolean closeProcessingThread;
private volatile boolean closeWatcherThread;
private void processFiles(){
System.out.println("DirWatchProcessingThread Started");
String fileName;
outerLoop: while(!closeProcessingThread || !fileProcessingQueue.isEmpty()){
try{
fileName = fileProcessingQueue.poll(1000, TimeUnit.MILLISECONDS);
}catch(InterruptedException ie){
fileName = null;
}
if(fileName == null || fileName.equals("")){
continue outerLoop;
}
long startTime = System.currentTimeMillis();
innerLoop: while(true){
FileInputStream fis = null;
File file = new File(fileName);
try{
fis = new FileInputStream(fileName);
break innerLoop;
}catch(FileNotFoundException fnfe){
if(!file.exists() || file.isDirectory()){
System.out.println("File: '"+fileName+"has been deleted in file system or it is not file. Not processing this file.");
continue outerLoop;
}
try{
Thread.sleep(WatchDirParameters.millisToPuaseForFileLock);
}catch(InterruptedException ie){
}
if((System.currentTimeMillis() - startTime) > WatchDirParameters.millisToSwapFileForUnlocking){
if(fileProcessingQueue.offer(fileName)){
continue outerLoop;
}else{
startTime = System.currentTimeMillis();
continue innerLoop;
}
}
}finally{
if(fis != null){
try{
fis.close();
}catch(IOException ioe){
ioe.printStackTrace();
}
}
}
}
System.out.println("Queuing File: "+fileName);
processedLoop:while(true){
try{
if(processedFileQueue.offer(fileName, 1000, TimeUnit.MILLISECONDS)){
break processedLoop;
}
}catch(InterruptedException ie){
//ie.printStackTrace();
}
}
}
closeWatcherThread = true;
closeProcessingThread = true;
System.out.println("DirWatchProcessingThread Exited");
}
/**
* Process all events for keys queued to the watcher
*/
private void processEvents(){
System.out.println("DirWatcherThread started.");
while(!closeWatcherThread) {
// wait for key to be signalled
WatchKey key;
try {
key = watcher.take();
} catch (InterruptedException x) {
// if we are returning from these method, it means we no longer wants to watch directory
// we must close thread which may be waiting for file names in queue
continue;
}catch(ClosedWatchServiceException cwse){
break;
}
Path dir = keys.get(key);
if (dir == null) {
System.err.println("WatchKey not recognized!!");
continue;
}
try{
for (WatchEvent<?> event: key.pollEvents()) {
WatchEvent.Kind kind = event.kind();
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);
if(kind.equals(ENTRY_CREATE)){
// if directory is created, and watching recursively, then
// register it and its sub-directories
if (recursive) {
try {
if (Files.isDirectory(child, NOFOLLOW_LINKS)) {
registerAll(child);
continue;
}
} catch (IOException x) {
// ignore to keep sample readbale
}
}
while(true){
if(fileProcessingQueue.remainingCapacity() < 2){
// if only one last can be inserted then don't queue this we need 1 empty space in queue
// for swaping file names..
// sleep for some time so processing thread may have made some rooms to queue in fileQueue
// this logic will not create any problems as only one this thread is inserting in queue
try{
Thread.sleep(200);
}catch(InterruptedException ie){
}
continue;
}
if(!fileProcessingQueue.offer(child.toString())){
// couldn't queue this element by whatever reason.. we will try to enqueue again by continuing loop
continue;
}else{
// file name has been queued in queue
break;
}
}
}
}
// 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;
}
}
}catch(ClosedWatchServiceException cwse){
break;
}
}
closeProcessingThread = true;
closeWatcherThread = true;
System.out.println("DirWatcherThread exited.");
}
public void stopWatching(){
try{
watcher.close();
}catch(IOException ioe){
}
closeProcessingThread = true;
closeWatcherThread = true;
}
public static WatchDir watchDirectory(String dirName, boolean recursive) throws InvalidPathException, IOException, Exception{
try{
Path dir = Paths.get(dirName);
final WatchDir watchDir = new WatchDir(dir, recursive);
watchDir.closeProcessingThread = false;
watchDir.closeWatcherThread = false;
new Thread(new Runnable() {
public void run() {
watchDir.processFiles();
}
}, "DirWatchProcessingThread").start();
new Thread(new Runnable() {
public void run() {
watchDir.processEvents();
}
}, "DirWatcherThread").start();
return watchDir;
}catch(InvalidPathException ipe){
throw ipe;
}catch(IOException ioe){
throw ioe;
}catch(Exception e){
throw e;
}
}
@SuppressWarnings("unchecked")
private 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);
WatchKey key = dir.register(watcher, ENTRY_CREATE);
if (trace) {
Path 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, BasicFileAttributes attrs) throws IOException {
register(dir);
return FileVisitResult.CONTINUE;
}
});
}
/**
* Creates a WatchService and registers the given directory
*/
private WatchDir(Path dir, boolean recursive) throws IOException {
fileProcessingQueue = new ArrayBlockingQueue<String>(WatchDirParameters.fileQueueSize, false);
processedFileQueue = new ArrayBlockingQueue<String>(WatchDirParameters.fileQueueSize, false);
this.watcher = FileSystems.getDefault().newWatchService();
this.keys = new HashMap<WatchKey,Path>();
this.recursive = recursive;
//CreateTxtFile.createFile(dir, 1);
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;
}
}
package dirwatch;
public class WatchDirParameters {
public static final int millisToPuaseForFileLock = 200;
public static final int fileQueueSize = 500;
public static final int millisToSwapFileForUnlocking = 2000;
}
制作了@UDPLover提供的文件的更新版本，该文件是为在高速文件访问环境中使用而构建的。我将to process队列转换为
HashMappackage filewatcher;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintStream;
import java.nio.file.ClosedWatchServiceException;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import static java.nio.file.LinkOption.NOFOLLOW_LINKS;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
import static java.nio.file.StandardWatchEventKinds.OVERFLOW;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.HashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
*
* @author Nackloose
* http://stackoverflow.com/questions/13998379/directory-watching-for-changes-in-java
*/
public abstract class WatchCore extends Thread {
//make class a thread by default
/**
* After the WatchCore recieves an event for a file and deems it unlocked,
* it will be passed to this function
*
* @param e WatchEvent for the file, after it has been affirmed to be
* unlocked.
*/
public abstract void onEventAndUnlocked(WatchEvent e);
private final WatchService watcher;
private final Map<WatchKey, Path> keys;
private final boolean recursive;
private boolean trace = false;
//converted to HashMap to remove the limitation as I need this in a high rate of file access enviroment.
//as well as to carry the event passed for that folder into the block check itself.
//got rid of the finished queue and made events pass to the abstract void above
private final HashMap<String, WatchEvent> fileProcessingQueue;
//create a varible to keep track of the thread checking the file blocking, so we can start and stop it.
private final WatchBlocker blocker;
public WatchCore(String dir) throws IOException {
//defaultly dont recurse
this(dir, false);
}
public WatchCore(String dir, boolean recursive) throws IOException {
this(Paths.get(dir), recursive);
}
public WatchCore(Path dir) throws IOException {
//defaultly dont recurse
this(dir, false);
}
public WatchCore(Path dir, boolean recursive) throws IOException {
fileProcessingQueue = new HashMap<>();
this.watcher = FileSystems.getDefault().newWatchService();
this.keys = new HashMap<>();
this.recursive = recursive;
//CreateTxtFile.createFile(dir, 1);
if (recursive) {
print("Scanning %s ...", dir);
registerAll(dir);
print("Done.");
} else {
register(dir);
}
// enable trace after initial registration
this.trace = true;
//start the thread to process files to be checked for file blocking
blocker = new WatchBlocker();
}
@SuppressWarnings("unchecked")
private static <T> WatchEvent<T> cast(WatchEvent<?> event) {
return (WatchEvent<T>) event;
}
@Override
public synchronized void start() {
//start up our thread _FIRST_
super.start();
//then start the blocking thread
blocker.start();
}
@Override
public void interrupt() {
//Everything backwards, stop the blocker _FIRST_
blocker.interrupt();
//then stop our thread.
super.interrupt();
}
/**
* 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);
WatchKey key = dir.register(watcher, ENTRY_CREATE);
if (trace) {
Path prev = keys.get(key);
if (prev == null) {
print("register: %s\n", dir);
} else {
if (!dir.equals(prev)) {
print("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, BasicFileAttributes attrs) throws IOException {
register(dir);
return FileVisitResult.CONTINUE;
}
});
}
/**
* Process all events for keys queued to the watcher
*/
@Override
public void run() {
//this was previous called processEvents()
//pruned any un-nessicary continues, labels, and labels on breaks, a lot of them
//were redundant
print("DirWatcherThread started.");
//as long as we're not interrupted we keep working
while (!interrupted()) {
// wait for key to be signalled
WatchKey key;
try {
key = watcher.take();
} catch (InterruptedException x) {
// if we are returning from these method, it means we no longer wants to watch directory
// we must close thread which may be waiting for file names in queue
continue;
} catch (ClosedWatchServiceException cwse) {
break;
}
Path dir = keys.get(key);
if (dir == null) {
printe("WatchKey not recognized!!");
continue;
}
try {
//converted to functional for loop.
key.pollEvents().stream().filter((event) -> {
WatchEvent.Kind kind = event.kind();
return !(kind == OVERFLOW); //make sure we do the filter
}).forEach((event) -> {
WatchEvent.Kind kind = event.kind();
// 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);
if (kind.equals(ENTRY_CREATE)) {
// if directory is created, and watching recursively, then
// register it and its sub-directories
if (recursive) {
try {
if (Files.isDirectory(child, NOFOLLOW_LINKS)) {
registerAll(child);
return; //continue;
}
} catch (IOException x) {
// ignore to keep sample readbale
}
}
fileProcessingQueue.put(child.toString(), ev);
}
});
// 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;
}
}
} catch (ClosedWatchServiceException cwse) {
break;
}
}
print("DirWatcherThread exited.");
}
/**
*
* @author
* http://stackoverflow.com/questions/13998379/directory-watching-for-changes-in-java
* Nackloose
*/
private class WatchBlocker extends Thread {
@Override
public synchronized void start() {
//get it going
super.start();
}
@Override
public void interrupt() {
//interupt our thread
super.interrupt();
}
@Override
public void run() {
//this was perviously processFiles()
//pruned any un-nessicary continues, labels, and labels on breaks, a lot of them
//were redundant
print("DirWatchProcessingThread Started");
Entry<String, WatchEvent> fileEvent;
outerLoop:
//as long as we're not interrupted we keep working
while (!interrupted()) {
if (fileProcessingQueue.isEmpty()) {
try {
Thread.sleep(WatchCoreParameters.timeToIdle);
} catch (InterruptedException ex) {
Logger.getLogger(WatchCore.class.getName()).log(Level.SEVERE, null, ex);
}
continue;
}
fileEvent = fileProcessingQueue.entrySet().iterator().next();
fileProcessingQueue.remove(fileEvent.getKey());
long startTime = System.currentTimeMillis();
while (true) {
FileInputStream fis = null;
File file = new File(fileEvent.getKey());
try {
fis = new FileInputStream(fileEvent.getKey());
break;
} catch (FileNotFoundException fnfe) {
if (!file.exists() || file.isDirectory()) {
print("File: '" + fileEvent + "has been deleted in file system or it is not file. Not processing this file.");
continue outerLoop;
}
try {
Thread.sleep(WatchCoreParameters.millisToPauseForFileLock);
} catch (InterruptedException ie) {
}
if ((System.currentTimeMillis() - startTime) > WatchCoreParameters.millisToSwapFileForUnlocking) {
fileProcessingQueue.put(fileEvent.getKey(), fileEvent.getValue());
}
} finally {
if (fis != null) {
try {
fis.close();
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
}
}
print("Queuing File: " + fileEvent);
//pass the unlocked file event to the abstract method
onEventAndUnlocked(fileEvent.getValue());
}
print("DirWatchProcessingThread Exited");
}
}
/**
*
* @author
* http://stackoverflow.com/questions/13998379/directory-watching-for-changes-in-java
* Nackloose
*/
public static class WatchCoreParameters {
public static int timeToIdle = 2000, millisToPauseForFileLock = 200,
millisToSwapFileForUnlocking = 2000;
public static boolean verbose = false;
}
//<editor-fold defaultstate="collapsed" desc="Printing methods">
private void print(String s) {
//defaultly we're not writing an error
print(s, false);
}
public static final void print(String s, boolean error) {
//check verbosity, exit if none.
if (!WatchCoreParameters.verbose) {
return;
}
//if this is an error, assign System.err to a temp varible
//otherise assign System.out for normal printing
PrintStream out = (!error ? System.out : System.err);
if (s.contains("\n")) { // check to see if theirs a new line
out.print(s); //print accordingly
} else {
out.println(s); //print accordingly
}
}
public static final void printe(String s) {
//shortcut/convenience method for printing an error
print(s, true);
}
public static final void print(String s, Object... formatObj) {
//check verbosity, exit if none.
if (!WatchCoreParameters.verbose) {
return;
}
//format the object into the string, and if no newline is there, add it.
System.out.format(s + (s.contains("\n") ? "" : "\n"), formatObj);
}
//</editor-fold>
}
packagefilewatcher；
导入java.io.File；
导入java.io.FileInputStream；
导入java.io.FileNotFoundException；
导入java.io.IOException；
导入java.io.PrintStream；
导入java.nio.file.ClosedWatchServiceException；
导入java.nio.file.FileSystems；
导入java.nio.file.FileVisitResult；
导入java.nio.file.Files；
导入静态java.nio.file.LinkOption.NOFOLLOW_链接；
导入java.nio.file.Path；
导入java.nio.file.path；
导入java.nio.file.SimpleFileVisitor；
导入静态java.nio.file.StandardWatchEventTypes.ENTRY\u创建；
导入静态java.nio.file.StandardWatchEventTypes.OVERFLOW；
导入java.nio.file.WatchEvent；
导入java.nio.file.WatchKey；
导入java.nio.file.WatchService；
导入java.nio.file.attribute.BasicFileAttributes；
导入java.util.HashMap；
导入java.util.Map；
导入java.util.Map.Entry；
导入java.util.logging.Level；
导入java.util.logging.Logger；
/**
*
*@作者Nackloose
* http://stackoverflow.com/questions/13998379/directory-watching-for-changes-in-java
*/
公共抽象类WatchCore扩展线程{
//默认情况下使类成为线程
/**
*WatchCore接收到文件的事件并认为其已解锁后，
*它将被传递到此函数
*
*@param e WatchEvent，在文件被确认为
*解锁。
*/
公开摘要无效，未锁定（观察事件e）；
私人最终观察者服务观察者；
私有最终映射密钥；
私有最终布尔递归；
私有布尔跟踪=false；
//转换为HashMap以消除限制，因为我需要在高速文件访问环境中使用它。
//以及进行传递给t的活动