Develop Reference

Vaadin EasyUpload add-on sometimes could not open or find file specified

We are currently using the EasyUpload add-on, and we have specified the criteria for this component:
a) only CSV files are allowed, with a cap size of 1MB per file.
b) only one file can be submitted at a time.
We just did an uploading test on small-sized CSV files that are below 100Kb. Usually, the upload process completes successfully. Occasionally, the error of "Could not open file, The system cannot find the file specified" is displayed although the file is already inside the temp folder, and we found that this happens either when:
a) If the same file is uploaded again after making a small change and within a few seconds after the file has been uploaded successfully.
b) If there are two tabs of the web app, logged under different users were uploading their respective csv files and they also do the same thing of changing values in the csv before uploading them again.
We tried forcing the file upload through (as another testing method) and noticed after a while that the files sometimes get stuck in the queue although we have imposed a one file at a submission time rule. It was displayed in a message "There are too many files over the count limit". We also considered of putting a sleep / wait command of 3-5 seconds after the file submission.
MultiFileUpload multiFileUpload = new MultiFileUpload() {
#Override
protected void handleFile(File tmpFile, String fileName, String mimeType, long length) {
String[] header = {"EOD_NUM","OUTLET_NAME","POSM_NAME","EOD_DATE","TOTAL_SALES","GROSS_SALES",
"TRAN_COUNT","VOID_COUNT","SERVICE_CHARGE","DISCOUNT_AMT","VAT_TAX_AMT","SVC_TAX_AMT","ROUNDING_ADJ"};
uploadLogger.debug("File: " + tmpFile.getAbsolutePath());
uploadLogger.debug("FileName: " + fileName);
uploadLogger.debug("MimeType: " + mimeType);
uploadLogger.debug("File Length: " + length);
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("ddMMyyyyHHmmss");
LocalDateTime now = LocalDateTime.now();
File f2 = null;
f2 = new File(busId+"_"+dtf.format(now)+".csv");
tmpFile.renameTo(f2);
try {
///var/lib/tomcat8/ in linux
///D:\\home\\site\\wwwroot\\ in Windows
uploadLogger.debug("f2 absolutepath: " + f2.getAbsolutePath());
uploadLogger.debug("f2 canonical path: " + f2.getCanonicalPath());
CloudBlockBlob blob = container.getBlockBlobReference(f2.getName());
if(f2.length() > 0){
blob.uploadFromFile(f2.getAbsolutePath());
Notification.show("File upload completed.",Notification.Type.TRAY_NOTIFICATION);
}
CSVReader reader = new CSVReader(new FileReader(f2.getAbsolutePath()), ',' , '"' , 0);
//read header name
//String[] myheader = reader.readNext();
//NOTE :: Store all row and column from csv info List of String Array
myEntries = reader.readAll();
if (myEntries != null && !myEntries.isEmpty()) {
boolean success = uploadDAO.insertUploaderEntry(myEntries,busId, userId,"");
uploadLogger.debug("SUCCESSS??? " + success);
if(success){
Notification successNotify = new Notification("Record has been created successfully.","Upload Successful!");
successNotify.setDelayMsec(3000);
successNotify.setStyleName(ValoTheme.NOTIFICATION_SUCCESS);
successNotify.setPosition(Position.MIDDLE_CENTER);
successNotify.show(Page.getCurrent());
}else {
Notification.show("Error in submitting uploaded record.","Upload failed!"
, Notification.Type.ERROR_MESSAGE).setDelayMsec(3000);
}
Thread.sleep(3000); //added to see if the delay solves the problem or not.
}
} catch (URISyntaxException | StorageException | IOException ex) {
new Notification("Could not open file",ex.getMessage(),Notification.Type.ERROR_MESSAGE).show(Page.getCurrent());
uploadLogger.debug(ex);
} catch (InterruptedException ix) {
uploadLogger.debug("Interrupted Exception found: " + ix.getMessage());
}
}
#Override
protected boolean supportsFileDrops() {
return false;
}
};
multiFileUpload.setMaxFileCount(1);
multiFileUpload.setUploadButtonCaption("Upload CSV file here");
multiFileUpload.setMaxFileSize(fileSizeLimit); // 2MB
multiFileUpload.setAcceptFilter(".csv");
We are unsure whether if this problem is a known limitation of the component or not.
Some of the questions we have discovered along the way are:
a) Is there a better way or to control on the file uploading and to avoid the open file / file not found error?
b) Are the values in the setAcceptedFilter method the mime/type values or something else. We noticed for images, it's "images/*" but for csv, we had to put in as ".csv"

Answering to your second question. The acceptFilter is directly passed to upload inputs "accept" attribute, so both .csv and text/csv should do fine. See https://www.w3schools.com/tags/att_input_accept.asp for more instructions.

Why am I getting 'nullfiles' when trying to copy a file from inside a jar to disk?

I am attempting to copy a file from inside my JAR to disk, outside the JAR file. The files that I will need to copy are default configuration files for a large-scale accounting system and are needed on the computer file system.
I have searched StackOverflow, as well as other sites (found with Google) and have read around fifty answers, which I've tried all of them. The code below is the first that has not simply blown up (with NullPointerException or FileNotFoundException), but has actually attempted to get the resource located in the JAR file.
I have my JAR file set up as follows:
com.is2300.isis
MainClass.java (actual name is crazy long and I don't want to type it out right now)
com.is2300.isis.resources
Location of the resource file I would like to copy out to disk
com.is2300.isis.utils
Location of my class ResourceExporter (below - bottom) that has the file exporting methods.
My MainClass.main() entry-point function:
public static void main(String[] args) {
// Test our 'utils.ResourceExporter.exportResource(String resourceName)
//+ function.
// Set the start point of our substring to either 5 or 9, depending upon
//+ if we are debugging (in NetBeans) or not (executing the JAR).
if ( isDebugging ) {
startPoint = 5;
} else {
startPoint = 9;
}
// First, we'll try just the name of the resource file to export.
String rsName = "nwind.conf";
try {
System.out.println(ResourceExporter.exportResource(rsName,
MainClass.class, "/home/user/tmp", startPoint));
} catch (Exception ex) {
System.err.println(ex.getCause());
System.err.println(ex.getMessage());
ex.printStackTrace(System.err);
}
// Then, we'll try it with the absolute path.
rsName = "/com/is2300/isis/resources/nwind.conf";
try {
System.out.println(ResourceExporter.exportResource(rsName,
MainClass.class, "/home/user/tmp", startPoint));
} catch (Exception ex) {
System.err.println(ex.getCause());
System.err.println(ex.getMessage());
ex.printStackTrace(System.err);
}
// Then, we'll try it with the relative path.
rsName = "../resources/nwind.conf";
try {
System.out.println(ResourceExporter.exportResource(rsName,
MainClass.class, "/home/user/tmp", startPoint));
} catch (Exception ex) {
System.err.println(ex.getCause());
System.err.println(ex.getMessage());
ex.printStackTrace(System.err);
}
// Last, we'll try it using dots instead of slashes.
rsName = "com.is2300.isis.resources.nwind.conf";
try {
System.out.println(ResourceExporter.exportResource(rsName,
MainClass.class, "/home/user/tmp", startPoint));
} catch (Exception ex) {
System.err.println(ex.getCause());
System.err.println(ex.getMessage());
ex.printStackTrace(System.err);
}
}
My ResourceExporter.exportResource() method:
public static String exportResource(String resourceName, Class cls,
String outPath, int startPoint) throws Exception {
File files = new File(cls.getResource(
cls.getResource(cls.getSimpleName() +
".class").toString().substring(
startPoint, cls.getResource(
cls.getSimpleName() + ".class").toString().lastIndexOf("/")
+ 1)) + "files");
InputStream in = new FileInputStream(files);
FileOutputStream out = new FileOutputStream(outPath +
resourceName.substring(resourceName.lastIndexOf("/")));
int readBytes;
byte[] buffer = new byte[4096];
while ( (readBytes = in.read(buffer)) > 0 )
out.write(buffer, 0, readBytes);
in.close();
out.close();
return files.getAbsolutePath();
}
With what I'm doing in public static void main(String[] args), I would expect one of the calls to the ResourceExporter.exportResource() method to actually cause the file to be copied.
However, when I step through the exportResource() method, on each call after the line:
File files = new File(cls.getResource(
cls.getResource(cls.getSimpleName() +
".class").toString().substring(
startPoint, cls.getResource(
cls.getSimpleName() + ".class").toString().lastIndexOf("/")
+ 1)) + "files");
The variable files.getCanonicalPath() call shows /home/user/Projects/ProjectName/nullfiles and I do not understand why this is, nor what this is.

#JBNizet and #AndrewThompson:
Thank you both for your comments. Especially #JBNizet! You gave me a swift kick in the head that made me look closer at what I had written and immediately saw the issue. Thank you very much for that.
The fix was this: Instead of the convoluted thing I was doing:
File files = new File(cls.getResource(
cls.getResource(cls.getSimpleName() +
".class").toString().substring(
startPoint, cls.getResource(
cls.getSimpleName() + ".class").toString().lastIndexOf("/")
+ 1)) + "files");
InputStream in = new FileInputStream(files);
FileOutputStream out = new FileOutputStream(outPath +
resourceName.substring(resourceName.lastIndexOf("/")));
Which I had written about 10 years ago and don't remember what I was thinking, I was able to simplify it to this:
InputStream in = ClassLoader.getSystemClassLoader().getSystemResourceAsStream(resourceName);
FileOutputStream out = new FileOutputStream(outPath +
resourceName.substring(resourceName.lastIndexOf("/")));
Now, the "file" (as a nod to the semantic correction by #AndrewThompson) is being located within the JAR file.
However, that was not the only change that had to be made. Where I set up the variable that is passed into the parameter resourceName was also not correct. I had it set up like so:
String rsName = "/com/is2300/isis/resources/nwind.conf";
However, the leading slash (/) was not supposed to be there. As soon as I changed the above line to:
String rsName = "com/is2300/isis/resources/nwind.conf";
everything just worked the way I expected.
Again, thanks to those two who commented. I appreciate your thoughts and assistance in getting my brain engaged.

Moving/Copying a file to another directory creates empty file and empties source

My goal is to move a file from one directory to another. The source is on a local drive and the destination is on a network drive. It doesn't matter whether I move or I copy then delete source. The file is approx 6GB.
What I've tried:
// C:\path\to\dir\file.bak
File source = new File(localRoot + backup);
// \\192.168.1.100\path\to\dir\file.bak
File dest = new File(storageRoot + "/" + storagePath + "/" + backup);
try {
log("Copying");
// I've tried copyFile as well.
FileUtils.copyFileToDirectory(source, dest);
log("copied");
} catch (Exception e) {
e.printStackTrace();
}
File source = new File(localRoot + backup);
File dest = new File(storageRoot + "/" + storagePath + "/" + backup);
try {
log("Copying");
// I've tried move and creating Paths instead of Files as well.
Files.copy(source.toPath(), dest.toPath());
log("copied")
} catch (Exception e) {
e.printStackTrace();
}
I've tried as well a manual method using Input, OutputStreams and reading bytes.
The results is that a file is created in the destination with the correct filename with 0 bytes, and the source file is rewritten from 6GB to 0 bytes. This happens for all methods I've tried, the only exception is that when I tried move, the source file was deleted rather than rewritten.
All code is in early development, please refrain from commenting on best practices.
Thank you, and what am I missing or what else can I try?

Loading a file without knowing its extention at runtime

Sorry if I sound unexperienced or make no sense, I'm currently in my second computer science year and I'm currently making a light 2D game engine in java for a school project ( We can choose what we want to do for this one ).
So I'm currently working on the asset manager. For now it contains a hashmap with assets and a InputStreamProvider.
The InputStreamProvider is an interface between the assetManager and different kind of providers. For now, I only have a FileProvider which provides a stream from a file.
For now everything is ok, but when it comes to actually retrive the file from an id, I got a small problem with the extension. I thought that one of the advantages of using an asset manager was that you could just use IDs for your assets, which is fine once they are loaded, but when you need to load them how do you know the file extention?
Here is my workaround which is obviously not a good solution using a config file which lists the extentions being used for the assets and then trying to load the file with every extention.
public class FileProvider extends AssetInputStreamProvider {
private final static String assetLocation = "assets/";
protected final static List<String> assetExtentions = new ArrayList<>();
static {
try {
InputStreamReader isr = new InputStreamReader(new FileInputStream(new File("conf/assets.cfg")));
while (isr.ready()) {
String ext = new String();
Character c = (char) isr.read();
while (!c.equals(',')) {
ext += c;
c = (char) isr.read();
}
assetExtentions.add(ext);
}
} catch (FileNotFoundException ex) {
Logger.getLogger(AssetInputStreamProvider.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Logger.getLogger(AssetInputStreamProvider.class.getName()).log(Level.SEVERE, null, ex);
}
}
#Override
public InputStream getInputStream(String type, String name) {
File file;
for (String assetExtention : assetExtentions) {
try {
System.out.println(assetLocation + type + "/" + name + "." + assetExtention);
file = new File(assetLocation + type + "/" + name + "." + assetExtention);
return new FileInputStream(file);
} catch (FileNotFoundException ex) {
Logger.getLogger(FileProvider.class.getName()).log(Level.SEVERE, null, ex);
}
}
return null;
}
}
So I'd like to know if there is a way to load a file without knowing its extention, or if I'm completely mistaken about the way to load assets and then if anyone could tell me the way to do it properly it would be really helpful.
And out of curiosity, it's out of the scope of my question but I've seen some people using integer for IDs but no matter how much I think about it, I can't figure how to do it without hardcoding resources and giving them an int value so I'd like to get some hints to know how to implement such a system too.
Thanks a lot for reading and have a good day.

Creating a file is causing problem, the File.getPath() doesn't seem to work

I am trying to create a back up file for an html file on a web server.
I want the backup to be in the same location as the existing file (it's a quick fix). I want to create the file using File file = new File(PathName);
public void backUpOldPage(String oldContent) throws IOException{
// this.uri is a class variable with the path of the file to be backed up
String fileName = new File(this.uri).getName();
String pathName = new File(this.uri).getPath();
System.out.println(pathName);
String bckPath = pathName+"\\"+bckName;
FileOutputStream fout;
try
{
// Open an output stream
fout = new FileOutputStream (bckFile);
fout.close();
}
// Catches any error conditions
catch (IOException e)
{
System.err.println ("Unable to write to file");
System.exit(-1);
}
}
But if instead I was to set bckPath like this, it will work.
String bckPath = "C://dev/server/tomcat6/webapps/sample-site/index_sdjf---sd.html";
I am working on Windows, not sure if that makes a difference.
The result of String bckPath = pathName+"\"+bckName;
is bckPath = C:\dev\server\tomcat6\webapps\sample-site\filename.html - this doesn't result in a new file.

Use File.pathSeparator, that way you dont need to worry what OS you are using.

Try to use File.getCanonicalPath() instead of plain getPath(). This helps if the orginal path is not fully specified.
Regarding slashes, / or \ or File.pathSeparator is not causing the problem, because they are all the same on Windows and Java. (And you do not define bckFile in your code, only bckPath. Also use getCanonicalPath() on the new created bckPath.)