Develop Reference

Implementing "Move" function with VFS

I'm trying to implement a wrapped "move" function with Xodus, but something is not working out right:
#Override
public boolean move(String appId, String name, String targetName) {
final boolean[] success = new boolean[1];
final Environment env = manager.getEnvironment(xodusRoot, appId);
final VirtualFileSystem vfs = manager.getVirtualFileSystem(env);
env.executeInTransaction(
new TransactionalExecutable() {
#Override
public void execute(#NotNull final Transaction txn) {
File file = vfs.openFile(txn, name, false);
InputStream input = vfs.readFile(txn, file);
if(input != null) {
File targetFile = vfs.openFile(txn, targetName, true);
DataOutputStream output = new DataOutputStream(vfs.writeFile(txn, targetFile));
try {
output.write(ByteStreams.toByteArray(input));
} catch (IOException e) {
e.printStackTrace();
}
vfs.deleteFile(txn, name);
success[0] = true;
}
}
});
// vfs.shutdown();
// env.close();
return success[0];
}
The problem is the file gets moved but the byte array is not getting copied, not sure if the problem is because of multiple VFS operation in the same transaction. Can someone give me a hint of why the bytes from the source file are not getting copied properly?

Looks like you are trying to implement another version of VirtualFileSystem.renameFile(..).

how to get/ make file object in the program given below

i am a nibble in java. i have my own efforts to get the things done. but certainly i am facing a challenge. i have a dummy program that searches for files of a particular extension(.txt) supplied as a command line argument. i am trying to make file objects of these searched file for further manipulations. but i can't understand how to do this in my code.. here is my code sample...
public class Find {
public static class Finder extends SimpleFileVisitor<Path> {
private final PathMatcher matcher;
private int numMatches = 0;
Finder(String pattern) {
matcher = FileSystems.getDefault().getPathMatcher("glob:" + pattern);
}
void find(Path file) {
Path name = file.getFileName();
if (name != null && matcher.matches(name)) {
numMatches++;
System.out.println(file);
}
}
// Prints the total number of
// matches to standard out.
void done() {
System.out.println("Matched: "+ numMatches);
}
// Invoke the pattern matching
// method on each file.
//#Override
public FileVisitResult visitFile(Path file,
BasicFileAttributes attrs) {
find(file);
return CONTINUE;
}
// Invoke the pattern matching
// method on each directory.
//#Override
public FileVisitResult preVisitDirectory(Path dir,
BasicFileAttributes attrs) {
find(dir);
return CONTINUE;
}
//#Override
public FileVisitResult visitFileFailed(Path file, IOException exc) {
System.err.println(exc);
return CONTINUE;
}
}
public static void main(String[] args) throws IOException {
Iterable<Path> root;
root = FileSystems.getDefault().getRootDirectories();
// System.out.println(name.getAbsolutePath());
for (Path startingDir : FileSystems.getDefault().getRootDirectories()) {
String pattern = args[0];
Finder finder = new Finder(pattern);
Files.walkFileTree(startingDir, finder);
}
}
}

here is what i am trying to do. the output of my program is a long list of text files with their absolute path. now i want to make objects of these files so that i can upload these to a URL. to upload them i have to make a stream with file object to be sent..how to get absoluteFilename?? to get this you must have a file object...right.... and my revised question is : how to make file objects of searched files???
FileInputStream fileInputStream = null;
try {
new FileInputStream("absoluteFilename");
byte[] buffer = new byte[MAX_SIZE];
int bufferIndex = 0;
while (fileInputStream.available() > 0) {
buffer[bufferIndex++] = (byte) fileInputStream.read();
}
byte[] fileContent = new byte[bufferIndex];
System.arraycopy(buffer,0,fileContent,0,bufferIndex);
URL serverUrl = new URL(url);
URLConnection connection = serverURL.openConnection();
connection.setConnectTimeout(60000);
connection.getOutputStream().write(fileContent);
} catch (Exception fatal) {
//proper handling??

Directory Scanner in Java

Scan a set of directories continuously for a set of file name filters.
For each file name filter arrived, process the file and repeat the steps for all
What can be the recommended design for this in jdk 1.5 , possibly using java.concurrent.Executor and Future

I have done a similar task with the web crawler.Just a few changes had to be made... It is a concurrent implementation with newly found directories getting scanned by the thread pool in the Executor Framework.It uses concurrent collections for Queue and List to hold the indexed files. The indexer picks up the files from the queue and does something with them.
here is the FileFilter implementation
public class ImageFileFilter implements FileFilter
{
private final String[] okFileExtensions =
new String[] {"jpg", "png", "gif"};
public boolean accept(File file)
{
for (String extension : okFileExtensions)
{
if (file.getName().toLowerCase().endsWith(extension))
{
return true;
}
}
return false;
}
}
here is the Class with the main method...
public class FileFilterTest {
public static void main(String[] args) {
File dir = new File("D:\\dev\\css-templates\\cms-admin");
BlockingQueue blockingQueue = new ArrayBlockingQueue(5);
FileCrawler fileCrawler = new FileCrawler(blockingQueue,
new ImageFileFilter(), dir);
new Thread(fileCrawler).start();
FileIndexer indexer = new FileIndexer(blockingQueue);
new Thread(indexer).start();
}
}
Here is the file crawler thread
public class FileCrawler implements Runnable {
private final BlockingQueue fileQueue;
private ConcurrentSkipListSet indexedFiles = new ConcurrentSkipListSet();
private final FileFilter fileFilter;
private final File root;
private final ExecutorService exec = Executors.newCachedThreadPool();
public FileCrawler(BlockingQueue fileQueue,
final FileFilter fileFilter,
File root) {
this.fileQueue = fileQueue;
this.root = root;
this.fileFilter = new FileFilter() {
public boolean accept(File f) {
return f.isDirectory() || fileFilter.accept(f);
}
};
}
public void run() {
submitCrawlTask(root);
}
private void submitCrawlTask(File f) {
CrawlTask crawlTask = new CrawlTask(f);
exec.execute(crawlTask);
}
private class CrawlTask implements Runnable {
private final File file;
CrawlTask(File file ) {
this.file= file;
}
public void run() {
if(Thread.currentThread().isInterrupted())
return;
File[] entries = file.listFiles(fileFilter);
if (entries != null) {
for (File entry : entries)
if (entry.isDirectory())
submitCrawlTask(entry);
else if (entry !=null && !indexedFiles.contains(entry)){
indexedFiles.add(entry);
try {
fileQueue.put(entry);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
}
}
}
}
Here is the file indexer thread
public class FileIndexer implements Runnable {
private final BlockingQueue queue;
public FileIndexer(BlockingQueue queue) {
this.queue = queue;
}
public void run() {
try {
while (true) {
indexFile(queue.take());
}
} catch (InterruptedException e) {
System.out.println("Indexer Interrupted");
Thread.currentThread().interrupt();
}
}
public void indexFile(File file) {
// do something with the file...
System.out.println("Indexing File : " + file.getAbsolutePath() + " " + file.getName());
};
}

I guess this is what you are trying to do:
You have a set of dirs:
dir1
dir2
dir3
And you need to place a "watch" on these 3 directories for a specific file name pattern.
Example: If a new file is added with name: watchme_9192.log, then you java logic should kick in and process that file.
So, based on that assumption, you can try: jnotify
JNotify is a java library that allow java application to listen to
file system events, such as:
File created
File modified
File renamed
File deleted
Also, related: best practice for directory polling

How to access files within folders within jar files?

I have looked at How to access resources in JAR file? and How do I copy a text file from a jar into a file outside of the jar? and many other questiions but couldnt actually get an answer. What I'm trying to do is copy contents of a file in res/CDC.txt that is in jar, to somewhere out of a jar. Now, on my computer it works but when I try it on different computer I get FileNotFoundException. So, I figured out why it works on mine. I have a CLASSPATH set to .;D:\myname\Java\JavaFiles where all my java files are located in packages. In "JavaFiles" directory there is also "res/CDC.txt". So, when I start my application, it first checks the current directory myapp.jar is located in for "res/CDC.txt", and then it checks "JavaFiles" and finds it. Other computers do not have it. So, this was my initial code:
public final class CT
{
//Other fields
private static CT ct;
private NTSystem nts;
private File f1;
private File f6;
private PrintWriter pw1;
private BufferedReader br1;
//Other fields
public static void main(String[] args)
{
try
{
showMessage("Executing program...");
ct = new CT();
ct.init();
ct.create();
ct.insertData();
//Other code
showMessage("Program executed!");
}
catch(Exception e)
{
showMessage("An exception occured! Program closed.");
e.printStackTrace();
System.exit(0);
}
}
private void init()
throws IOException
{
//Other initialization
nts = new NTSystem();
f1 = new File("C:\\Users\\" + nts.getName() + "\\blahblah");
f6 = new File("res\\CDC.txt");
br1 = new BufferedReader(new FileReader(f6));
//Other initialization
showMessage("Initialized");
}
private void create()
throws IOException
{
//Makes sure file/dir exists, etc
pw1 = new PrintWriter(new BufferedWriter(new FileWriter(f1)), true);
//Other Stuff
showMessage("Created");
}
private void insertData()
throws IOException
{
String line = br1.readLine();
while(line != null)
{
pw1.println(line);
line = br1.readLine();
}
//Other stuff
showMessage("Data inserted");
}
private static void showMessage(String msg)
{
System.out.println(msg);
}
}
which I changed to
public final class CT
{
//Other fields
private static CT ct;
private NTSystem nts;
private byte[] buffer;
private File f1;
private URL url1;
private FileOutputStream fos1;
private InputStream is1;
//Other fields
public static void main(String[] args)
{
try
{
showMessage("Executing program...");
ct = new CT();
ct.init();
ct.create();
ct.insertData();
//Other code
showMessage("Program executed!");
}
catch(Exception e)
{
showMessage("An exception occured! Program closed.");
e.printStackTrace();
System.exit(0);
}
}
private void init()
throws IOException
{
//Other initialization
nts = new NTSystem();
buffer = new byte[4096];
f1 = new File("C:\\Users\\" + nts.getName() + "\\blahblah");
url1 = getClass().getClassLoader.getResource("res\\CDC.txt"); //Also tried url1 = ct.getClass().getClassLoader.getResource("res\\CDC.txt"); or url1 = this.getClass().getClassLoader.getResource("res\\CDC.txt"); or url1 = CT.getClass().getClassLoader.getResource("res\\CDC.txt");
is1 = url1.openStream();
//Other initialization
showMessage("Initialized");
}
private void create()
throws IOException
{
//Makes sure file/dir exists, etc
pw1 = new PrintWriter(new BufferedWriter(new FileWriter(f1)), true);
//Other Stuff
showMessage("Created");
}
private void insertData()
throws IOException
{
int read = is1.read(buffer);
while(line != null)
{
fos1.write(buffer, 0, read);
read = is1.read(buffer);
}
//Other stuff
showMessage("Data inserted");
}
private static void showMessage(String msg)
{
System.out.println(msg);
}
}
And this time I always get NullPointerException. So, how to read folders and files that are within jar?
Thanks

You will want to use getSystemResourceAsStream() to read the contents from files in a jar.
This of course is assuming the file is actually on the classpath of the other users computers.

JTextArea appending problems

Im making a backup program, and I want everything that i have the program backing up displayed on a JTextArea. well, it works, but only after the program is finished with the backup. How do i fix this? The code i have running this is here:
backup method
public void startBackup() throws Exception {
// txtarea is the JTextArea
Panel.txtArea.append("Starting Backup...\n");
for (int i = 0; i < al.size(); i++) {
//al is an ArrayList that holds all of the backup assignments selected
// from the JFileChooser
File file = new File((String) al.get(i));
File directory = new File(dir);
CopyFolder.copyFolder(file, directory);
}
}
Copy Folder class:
public class CopyFolder {
public static void copyFolder(File src, File dest) throws IOException {
if (src.isDirectory()) {
// if directory not exists, create it
if (!dest.exists()) {
dest.mkdir();
Panel.txtArea.append("Folder " + src.getName()
+ " was created\n");
}
// list all the directory contents
String files[] = src.list();
for (String file : files) {
// construct the src and dest file structure
File srcFile = new File(src, file);
File destFile = new File(dest, file);
// recursive copy
copyFolder(srcFile, destFile);
}
} else {
try {
CopyFile.copyFile(src, dest);
} catch (Exception e) {
}
}
}
}
CopyFile class
public class CopyFile {
public static void copyFile(File src, File dest) throws Exception {
// if file, then copy it
// Use bytes stream to support all file types
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
// copy the file content in bytes
while ((length = in.read(buffer)) > 0) {
out.write(buffer, 0, length);
}
in.close();
out.close();
// System.out.println("File copied from " + src + " to " + dest);
Panel.txtArea.append("File copied " + src.getName() + "\n");
}
}
Thanks for the help in advance, and let me know of any assistance i can give. I did a google search on this, and it does seem to be a big problem, but i just cant think of how to fix it. Oh, and please dont downvote this just because it doesnt apply to you, its very aggravating. Thanks in advance again!
EDIT:
This is what i got:
public class test extends SwingWorker<Void, String> {
String txt;
JTextArea txtArea = null;
public test(JTextArea txtArea, String str) {
txt = str;
this.txtArea = txtArea;
}
protected Void doInBackground() throws Exception {
return null;
}
protected void process(String str) {
txtArea.append(str);
}
protected void getString() {
publish(txt);
}
}

The main problem you're having is you're trying to perform blocking actions in the Event Dispatching Thread. This will prevent the UI from been updated as repaint requests are not reaching the repaint manager until AFTER you've finished.
To over come this, you're going to need to off load the blocking work (ie the back up process) to a separate thread.
For this I suggest you have a read through the Concurrency in Swing Trail which will provide you with some useful strategies to solve your particular problem. In particular, you'll probably benifit from using a SwingWorker
Take a close look at doInBackground and the process methods
UPDATED with Example
Okay, so this is a REALLY simple example. This basically walks you C:\ drive to 3 directories deep and dumps the content to the supplied JTextArea
public class BackgroundWorker extends SwingWorker<Object, File> {
private JTextArea textArea;
public BackgroundWorker(JTextArea textArea) {
this.textArea = textArea;
}
#Override
protected Object doInBackground() throws Exception {
list(new File("C:\\"), 0);
return null;
}
#Override
protected void process(List<File> chunks) {
for (File file : chunks) {
textArea.append(file.getPath() + "\n");
}
textArea.setCaretPosition(textArea.getText().length() - 1);
}
protected void list(File path, int level) {
if (level < 4) {
System.out.println(level + " - Listing " + path);
File[] files = path.listFiles(new FileFilter() {
#Override
public boolean accept(File pathname) {
return pathname.isFile();
}
});
publish(path);
for (File file : files) {
System.out.println(file);
publish(file);
}
files = path.listFiles(new FileFilter() {
#Override
public boolean accept(File pathname) {
return pathname.isDirectory() && !pathname.isHidden();
}
});
for (File folder : files) {
list(folder, level + 1);
}
}
}
}
You would simply call new BackgroundWorker(textField).execute() and walk away :D
UPDATED with explicit example
public class BackgroundWorker extends SwingWorker<Object, String> {
private JTextArea textArea;
private File sourceDir;
private File destDir;
public BackgroundWorker(JTextArea textArea, File sourceDir, File destDir) {
this.textArea = textArea;
this.sourceDir = sourceDir;
this.destDir = destDirl
}
#Override
protected Object doInBackground() throws Exception {
if (sourceDir.isDirectory()) {
// if directory not exists, create it
if (!destDir.exists()) {
destDir.mkdir();
publish("Folder " + sourceDir.getName() + " was created");
}
// list all the directory contents
String files[] = sourceDir.list();
for (String file : files) {
// construct the src and dest file structure
File srcFile = new File(sourceDir, file);
File destFile = new File(destDir, file);
// recursive copy
copyFolder(srcFile, destFile);
}
} else {
try {
copyFile(sourceDir, destDir);
} catch (Exception e) {
}
}
return null;
}
public void copyFolder(File src, File dest) throws IOException {
if (src.isDirectory()) {
// if directory not exists, create it
if (!dest.exists()) {
publish("Folder " + src.getName() + " was created");
}
// list all the directory contents
String files[] = src.list();
for (String file : files) {
// construct the src and dest file structure
File srcFile = new File(src, file);
File destFile = new File(dest, file);
// recursive copy
copyFolder(srcFile, destFile);
}
} else {
try {
copyFile(src, dest);
} catch (Exception e) {
}
}
}
public void copyFile(File src, File dest) throws Exception {
// if file, then copy it
// Use bytes stream to support all file types
InputStream in = new FileInputStream(src);
OutputStream out = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
// copy the file content in bytes
while ((length = in.read(buffer)) > 0) {
out.write(buffer, 0, length);
}
in.close();
out.close();
publish("File copied " + src.getName());
}
#Override
protected void process(List<String> chunks) {
for (String msg : chunks) {
textArea.append(msg + "\n");
}
textArea.setCaretPosition(textArea.getText().length() - 1);
}
}
Now to run...
new BackgroundWorker(textArea, sourceDir, destDir).execute();