Develop Reference

FileNotFound exception even though file is in the place during watch service in java

I have a watch service running on a folder, when I am trying to modify and existing file using evenKind == Modify (basically pasting a same file without removing the current file) I am getting FileNotFoundException (The process cannot access the file because it is being used by another process.)
if (eventKind == StandardWatchEventKinds.ENTRY_MODIFY) {
String newFileChecksum = null;
if (eventPath.toFile().exists()) {
newFileChecksum = getFileChecksum(eventPath.toFile());
}
if (fileMapper.containsKey(eventPath)) {
String existingFileChecksum = fileMapper.get(eventPath);
if (!existingFileChecksum.equals(newFileChecksum)) {
fileMapper.replace(eventPath, existingFileChecksum, newFileChecksum);
log.info("listener.filemodified IN");
for (DirectoryListener listener : this.listeners) {
listener.fileModified(this, eventPath);
}
log.info("listener.filemodified OUT");
} else {
log.info("existing checksum");
log.debug(String.format(
"Checksum for file [%s] has not changed. Skipping plugin processing.",
eventPath.getFileName()));
}
}
}
In the code when...getFileChecksum() is called
if (eventPath.toFile().exists()) {
newFileChecksum = getFileChecksum(eventPath.toFile());
}
So ideally, eventPath.toFile().exists() is TRUE, hence code is going inside if but when getFileChecksum() is called, it goes to method...
private synchronized String getFileChecksum(File file) throws IOException, NoSuchAlgorithmException {
MessageDigest md5Digest = MessageDigest.getInstance("MD5");
FileInputStream fis = null;
if(file.exists()) {
try {
fis = new FileInputStream(file);
} catch(Exception e) {
e.printStackTrace();
}
} else {
log.warn("File not detected.");
}
byte[] byteArray = new byte[1024];
int bytesCount = 0;
while ((bytesCount = fis.read(byteArray)) != -1) {
md5Digest.update(byteArray, 0, bytesCount);
};
fis.close();
byte[] bytes = md5Digest.digest();
StringBuilder stringBuilder = new StringBuilder();
for (int i=0; i< bytes.length ;i++) {
stringBuilder.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));
}
return stringBuilder.toString();
}
}
An exception is coming fis = new FileInputStream(file); even if the file is present in the folder.
FileNotFoundException (The process cannot access the file because it is being used by another process.)
I created a RandomAccessFile and a channel to release any LOCK placed on file, but it is not working. Please suggest what could be happening here.
//UPDATE --> This is the infinite while loop that I have,
WHAT IS HAPPENING? WHEN I PUT A FILE 1 create and 2 update are getting called, suppose, when I am deleting the file, 1 delete 1 modify is being called, and IF I PUT THE SAME FILE BACK TO FOLDER, I GET CREATE but before CREATE is finishing, MODIFY IS BEING called. and create is not running instead modify is running.
I fixed this issue by putting Thread.sleep(500) between
WatchKey wk = watchService.take();
Thread.sleep(500)
for (WatchEvent<?> event : wk.pollEvents()) {
But I dont think I can justify use of sleep here. Please help
WatchService watchService = null;
WatchKey watchKey = null;
while (!this.canceled && (watchKey == null)) {
watchService = watchService == null
? FileSystems.getDefault().newWatchService() : watchService;
watchKey = this.directory.register(watchService,
StandardWatchEventKinds.ENTRY_MODIFY, StandardWatchEventKinds.ENTRY_DELETE,
StandardWatchEventKinds.ENTRY_CREATE);
}
while (!this.canceled) {
try {
WatchKey wk = watchService.take();
for (WatchEvent<?> event : wk.pollEvents()) {
Kind<?> eventKind = event.kind();
System.out.println("Event kind : " + eventKind);
Path dir = (Path)wk.watchable();
Path eventPath = (Path) event.context();
Path fullPath = dir.resolve(eventPath);
fireEvent(eventKind, fullPath);
}
wk.reset();
}

I have a better approach, use and a while loop on a var isFileReady like this...
var isFileReady = false;
while(!isFile...) {
}
inside while create a try and catch.
try {
FileInputStream fis = new FileInputStream();
isFileReady = true;
} catch () {
catch exception or print file not ready.
}
This will solve your problem.

The WatchService is verbose and may report multiple ENTRY_MODIFY events for save operation - even when another application is part way through or doing writes repeatedly. Your code is probably acting on a modify event while the other app is still writing and there may be a second ENTRY_MODIFY on its way.
A safer strategy for using the WatchService is to collate the events you receive and only act on the changes when there is a pause. Something like this will ensure that you block on first event but then poll the watch service with small timeout to see if more changes are present before you act on the previous set:
WatchService ws = ...
HashSet<Path> modified = new HashSet<>();
while(appIsRunning) {
int countNow = modified.size();
WatchKey k = countNow == 0 ? ws.take() : ws.poll(1, TimeUnit.MILLISECONDS);
if (k != null) {
// Loop through k.pollEvents() and put modify file path into modified set:
// DO NOT CALL fireEvent HERE, save the path instead:
...
if (eventKind == ENTRY_MODIFY)
modified.add(filePath);
}
// Don't act on changes unless no new events:
if (countNow == modified.size()) {
// ACT ON modified list here - the watch service did not report new changes
for (Path filePath : modified) {
// call fireEvent HERE:
fireEvent(filePath);
}
// reset the list so next watch call is take() not poll(1)
modified.clear();
}
}
If you are also looking out for CREATE and DELETE operations with MODIFY you will have to collate and ignore some of the earlier events because the last recorded event type can take precedence over a previously recorded type. For example, if calling take() then poll(1) until nothing new is reported:
Any DELETE then CREATE => you might want to consider as MODIFY
Any CREATE then MODIFY => you might want to consider as CREATE
Any CREATE or MODIFY then a DELETE => treat as DELETE
Your logic would also want to only act when value of modified.size() + created.size() + deleted.size() gets changed between runs.

let me guess...
modify event gets called when you modify a file. to modify the file you most likely use a seperate tool like notepad that opens and LOCKS the file.
your watcher gets an event that the file gets modified (right now) but you can not modify it again (which fileinputstream wants to do) since it is locked already.

How to put multiple assets in a data event for Android Development

I am trying to make an app that sends files from my Android Watch to my Android Phone.
The problem I have is that if I record and save multiple files and send all of them at the same time, I do not get all the files back on the phone side. I only receive one file.
The code for sending the file is as follows. This code is implemented on the Watch side.:
public void sendData(View v){
String fname = "_Activity.bin";
int FileCounterCopy = FileCounter;
if(mGoogleApiClient.isConnected()){
for (int i = 0; i < FileCounterCopy ; i++){
String FileName = String.valueOf(i) + fname;
File dataFile = new File(Environment.getExternalStorageDirectory(), FileName);
Log.i("Path", Environment.getExternalStorageDirectory().toString());
Log.i("file", dataFile.toString());
Asset dataAsset = createAssetfromBin(dataFile);
sensorData = PutDataMapRequest.create(SENSOR_DATA_PATH);
sensorData.getDataMap().putAsset("File", dataAsset);
PutDataRequest request = sensorData.asPutDataRequest();
Wearable.DataApi.putDataItem(mGoogleApiClient, request).setResultCallback(new ResultCallback<DataApi.DataItemResult>() {
#Override
public void onResult(DataApi.DataItemResult dataItemResult) {
Log.e("SENDING IMAGE WAS SUCCESSFUL: ", String.valueOf(dataItemResult.getStatus().isSuccess()));
}
});
boolean deleted = dataFile.delete();
Log.i("Deleted", String.valueOf(deleted));
FileCounter--;
}
mTextView.setText(String.valueOf(FileCounter));
Return();
}
else {
Log.d("Not", "Connecteddddddddd");
}
}
The code for receiving the files is as follows and is implemented on the phone side.
#Override
public void onDataChanged(DataEventBuffer dataEvents) {
Counter++;
final List<DataEvent> events = FreezableUtils.freezeIterable(dataEvents);
dataEvents.close();
Log.e("List Size: ", String.valueOf(events.size()));
for (DataEvent event : events) {
if (event.getType() == DataEvent.TYPE_CHANGED) {
Log.v("Data is changed", "========================");
String path = event.getDataItem().getUri().getPath();
if (SENSOR_DATA_PATH.equals(path)) {
DataMapItem dataMapItem = DataMapItem.fromDataItem(event.getDataItem());
fileAsset = dataMapItem.getDataMap().getAsset("File");
myRunnable = createRunnable();
if (checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED)
new Thread(myRunnable).start();
}
}
}
status.setText("Received" + " File_"+ String.valueOf(Counter) );
}
Right before the for loop, I check the size of the event and it only shows a size of 1, no matter how many files I save.
I am stuck on how to implement this (tbh I used code from youtube video/online resources so I am not 100% sure on how some of the api works).
Thanks in advance!

You're putting all of the files at the same path, with nothing to differentiate them - so each one you put in overwrites the previous ones. The Data API works much like a filesystem in this regard.
In your sendData method, you need code something like this:
sensorData = PutDataMapRequest.create(SENSOR_DATA_PATH + '/' + dataFile.toString());
And then in onDataChanged, either only check the path prefix...
if (path.startsWith(SENSOR_DATA_PATH)) {
...or, preferably, put the value of SENSOR_DATA_PATH in your manifest declaration as an android:pathPrefix element in the intent-filter of your data receiver. You can then remove the path check from your Java code completely. Docs for that are here: https://developers.google.com/android/reference/com/google/android/gms/wearable/WearableListenerService
One other thing: it's good practice to clear stuff like these files out of the Data API when you're done using them, so that they're not taking up space there.

Count the account of the files at first and send a different file every minute

I have a folder named collect, there will be some files such as selectData01.json, selectData02.json, selectData03.json and so on.
I have to count the account of the files at first, and then I will send a different file every minute.
Now I want to konw how to achieve the purpose
public String getData() {
String strLocation = new SendSituationData().getClass().getProtectionDomain().getCodeSource().getLocation().getPath();
log.info("strLocation = ");
// String strParent = new File(strLocation).getParent() + "/collectData/conf.properties";
// System.out.println("strParent = " + strParent);
File fileConf = new File("collect/");
System.out.println("fileConf = " + fileConf.getAbsolutePath());
List<List<String>> listFiles = new ArrayList<>();
//File root = new File(DashBoardListener.class.getClassLoader().getResource("collectData/").getPath());
//File root = new File("collectData/application.conf");
File root = new File(fileConf.getAbsolutePath());
System.out.println("root.listFiles( ) = " + root.listFiles( ));
Arrays
.stream(Objects.requireNonNull(root.listFiles( )))
.filter(file -> file.getName().endsWith("json"))
.map(File::toPath)
.forEach(path -> {
try {
//List<String> lines = Files.readAllLines(path);
//System.out.println("lines = " + lines);
List<String> lines = Files.readAllLines(path);
listFiles.add(lines);
} catch (IOException e) {
e.printStackTrace( );
}
});
String dataBody = listToString(listFiles.get(0));
//log.info(dataBody);
ResultMap result = buildRsult();
//String jsonString = JSON.toJSONString(result);
}
public static String listToString(List<String> stringList){
if (stringList == null) {
return null;
}
StringBuilder result=new StringBuilder();
boolean flag=false;
for (String string : stringList) {
if (flag) {
result.append("");
}else {
flag=true;
}
result.append(string);
}
return result.toString();
}
supplement
My friend, maybe i don't express my purpose explicitly. If I have three files, I will sent the first file in the 0:00, sent the second file in the 0:01, sent the third file in the 0:03, sent the first file in the 0:04, sent the second file in the 0:05 and so on.
If I have five files, I will sent the first file in the 0:00, sent the second file in the 0:01, sent the third file in the 0:03, sent the fourth file in the 0:04, sent the fifth file in the 0:05 and so on.
I want to know how to achieve the function
supplement
I have a struct Project that contains a folder named collect. Each file represents a string.
At first, I want to calculate the number of files in collect folder, and then I will send a file every minute.
Any suggestions?

I would use Apache camel with file2 component.
http://camel.apache.org/file2.html
Please read about 'noop' option before running any tests.
Processed files are deleted by default as far as I remember.
Update - simple example added:
I would recommend to start with https://start.spring.io/
Add at least two dependencies: Web and Camel (requires Spring Boot >=1.4.0.RELEASE and <2.0.0.M1)
Create new route, you can start from this example:
#Component
public class FileRouteBuilder extends RouteBuilder {
public static final String DESTINATION = "file://out/";
public static final String SOURCE = "file://in/?noop=true";
#Override
public void configure() throws Exception {
from(SOURCE)
.process(exchange -> {
//your processing here
})
.log("File: ${file:name} has been sent to: " + DESTINATION)
.to(DESTINATION);
}
}
My output:
2018-03-22 15:24:08.917 File: test1.txt has been sent to: file://out/
2018-03-22 15:24:08.931 File: test2.txt has been sent to: file://out/
2018-03-22 15:24:08.933 File: test3.txt has been sent to: file://out/

How to update a perticular row in mpx file using MPXWriter in java

i am trying to update mpx file using MPXWrite,
Actually i converted mpp file to mpx file so that now i am able to read all the tasks and task details. But i want to update % Completion on particular task in mpx file how i do that.
Can any one provide code for that.
Thanks in Advance.. Please help me out from this problem
// Like this i am reading mpx file
private static void readMPX(String inputFile){
File f = new File(inputFile);
MPXReader read1 = new MPXReader();
ProjectFile pFile = null;
try{
pFile = read1.read(f);
}catch(Exception e){
e.printStackTrace();
}
List llist=pFile.getAllTasks();
for(int i=1;i<10/*llist.size()*/;i++)
{
Task t=(Task)llist.get(i);
System.out.println("------------------------------------");
System.out.println("Task Details : "+i +llist.get(i));
System.out.println("WBS : "+t.getWBS());
System.out.println("WBS Leve : "+t.getWBSLevel());
System.out.println("Task name : "+t.getName());
System.out.println("Duration : "+t.getDuration());
//System.out.println("Task Unique ID : "+t.getUniqueID());
// System.out.println("Task Unique ID : "+t.getUniqueID());
System.out.println("Base Line Start : "+t.getBaselineStart());
System.out.println("Base Line Finish : "+t.getBaselineFinish());
System.out.println("Actual Start Date : "+t.getActualStart());
// System.out.println("\tFinish Date : "+t.getFinish());
System.out.println("Actual End Date : "+t.getActualFinish());
System.out.println("% Complete : "+t.getPercentageComplete());
//getSubTasks(t,t.getUniqueID());
System.out.println("------------------------------------");
}
}

Here is some sample code for you:
private static void readMPX(String inputFile, String outputFile)
{
File f = new File(inputFile);
MPXReader read1 = new MPXReader();
ProjectFile pFile = read1.read(f);
// Select the task you want to update
// Here we are just selecting the first task
Task task = pFile.getTaskByID(1);
// Let's set it to 60% complete
task.setPercentageComplete(60);
// Now we write the result to a new file
new MPXWriter().write(pFile, outputFile);
}

Its a restriction from Microsoft. We cant write back to mpp file.

Log changes in XMLConfiguration file

I have a configuration file (an XML) which I load using XMLConfiguration.
I need to make sure that this XMLConfiguration instance is updated ( every 30 seconds ).
For that matter I have the following code:
XMLConfiguration configuration = new XMLConfiguration(configFile);
configuration.setAutoSave(true);
FileChangedReloadingStrategy strategy = new FileChangedReloadingStrategy();
strategy.setRefreshDelay(getRefreshDelay());
configuration.setReloadingStrategy(strategy);
It works great, but the thing is I want to log any changes in this XML file.
Is there a way of doing it?

I got it!
All I need to do is this:
ConfigurationListener listener = new ConfigurationListener() {
#Override
public void configurationChanged(ConfigurationEvent event) {
if ( !event.isBeforeUpdate() ){
System.out.println(event.getPropertyName() + " " + event.getPropertyValue());
}
}
};
configuration.addConfigurationListener(listener);
It works!