I have been trying many ways of downloading a file from a URL and putting it in a folder.
public static void saveFile(String fileName,String fileUrl) throws MalformedURLException, IOException {
FileUtils.copyURLToFile(new URL(fileUrl), new File(fileName));
}
boolean success = (new File("File")).mkdirs();
if (!success) {
Status.setText("Failed");
}
try {
saveFile("DownloadedFileName", "ADirectDownloadLinkForAFile");
} catch (MalformedURLException ex) {
Status.setText("MalformedURLException");
Logger.getLogger(DownloadFile.class.getName()).log(Level.SEVERE, null, ex);
} catch (IOException ex) {
Status.setText("IOException Error");
Logger.getLogger(DownloadFile.class.getName()).log(Level.SEVERE, null, ex);
}
I found this code on the net, am i using it correctly?
If i did:
saveFile("FolderName", "ADirectDownloadLinkForAFile")
I would get IOException error
What I want my code to do is:
Create folder
Download file
Downloaded file to go to the just created folder
I'm a newbie here sorry. Please help
There are various ways in java to download a file from the internet.
The easiest one is to use a buffer and a stream:
File theDir = new File("new folder");
// if the directory does not exist, create it
if (!theDir.exists())
{
System.out.println("creating directory: " + directoryName);
boolean result = theDir.mkdir();
if(result){
System.out.println("DIR created");
}
}
FileOutputStream out = new FileOutputStream(new File(theDir.getAbsolutePath() +"filename"));
BufferedInputStream in = new BufferedInputStream(new URL("URLtoYourFIle").openStream());
byte data[] = new byte[1024];
int count;
while((count = in.read(data,0,1024)) != -1)
{
out.write(data, 0, count);
}
Just the basic concept. Dont forget the close the streams ;)
The File.mkdirs() statement appears to be creating a folder called Files, but the saveFile() method doesn't appear to be using this, and simply saving the file in the current directory.
Related
This spring app performs simple file upload,
here's the controller class
#Override
public String fileUpload(MultipartFile file) {
try{
// save uploaded image to images folder in root dir
Files.write(Paths.get("images/"+ file.getOriginalFilename()), file.getBytes());
// perform some tasks on image
return "";
} catch (IOException ioException) {
return "File upload has failed.";
} finally {
Files.delete(Paths.get("images/" + file.getOriginalFilename()));
}
}
but when i build jar and runs, it throws IOException saying,
java.nio.file.NoSuchFileException: images\8c9.jpeg.
So my question is how can i add the images folder inside the jar executable itself.
Thanks.
You should provide a full path for the images folder, or save in java.io.tmpdir creating the image folder first.
But, in my opinion you should configure your upload folder from a config file for flexibility. Take a look at this.
app:
profile-image:
upload-dir: C:\\projs\\web\\profile_image
file-types: jpg, JPG, png, PNG
width-height: 360, 360
max-size: 5242880
In your service or controller, do whatever you like, may be validate image type, size etc and process it as you like. For instance, if you want thumbnails(or avatar..).
In your controller or service class, get the directory:
#Value("${app.image-upload-dir:../images}")
private String imageUploadDir;
Finally,
public static Path uploadFileToPath(String fullFileName, String uploadDir, byte[] filecontent) throws IOException {
Path fileOut = null;
try{
Path fileAbsolutePath = Paths.get(StringUtils.join(uploadDir, File.separatorChar, fullFileName));
fileOut = Files.write(fileAbsolutePath, filecontent);
}catch (Exception e) {
throw e;
}
return fileOut; //full path of the file
}
For your question in the comment: You can use java.io.File.deleteOnExit() method, which deletes the file or directory defined by the abstract path name when the virtual machine terminates. TAKE A GOOD CARE THOUGH, it might leave some files if not handled properly.
try (ByteArrayOutputStream output = new ByteArrayOutputStream();){
URL fileUrl = new URL(url);
String tempDir = System.getProperty("java.io.tmpdir");
String path = tempDir + new Date().getTime() + ".jpg"; // note file extension
java.io.File file = new java.io.File(path);
file.deleteOnExit();
inputStream = fileUrl.openStream();
ByteStreams.copy(inputStream, output); // ByteStreams - Guava
outputStream = new FileOutputStream(file);
output.writeTo(outputStream);
outputStream.flush();
return file;
} catch (Exception e) {
throw e;
} finally {
try {
if(inputStream != null) {
inputStream.close();
}
if(outputStream != null) {
outputStream.close();
}
} catch(Exception e){
//skip
}
}
New edit:
Now i found the cause, it is because there are two servers and it write into temp folder in 1st server and try to read from the 2nd one. But I still didn't find a solution for this unless write to Amazon S3 and read from there.
I tried to export csv with struts2 action. However if I tried to export 10 times i can only succeed once, all the others failed with File not found exception (if I refresh the link again, the file can be downloaded). Here is my code:
public String exportFile(String fileName) {
File exportFile = null;
try {
if (CollectionUtils.isEmpty(receipts)) {
return "";
}
exportFile = File.createTempFile(fileName, ".csv");
exportFile.deleteOnExit();
try (BufferedWriter fw = new BufferedWriter(new FileWriter(exportFile))) {
try {
fw.write("test");
} finally {
fw.close();
}
}
return exportFile.getPath();
} catch (Exception ex) {
logger.error("Error exporting report. ", ex.getMessage());
}
return "";
}
String getStreamFromPath(String filePath) {
try {
File downloadFile = new File(filePath);
fileInputStream = new FileInputStream(downloadFile);
return SUCCESS;
} catch (IOException e) {
log.error(e.getMessage(), e);
return ERROR;
}
}
This is really weird, when i test in another server it works totally fine. Any ideas?
there is a text file that an application produces, I would like to take that file and read it as strings in my application. How can I achieve that, any help would be grateful. Both applications are my applications so I can get the permissions.
Thank you!
This is possible using the standard android-storage, where all the user's files are stored too:
All you need to do is to access the same file and the same path in both applications, so e.g.:
String fileName = Environment.getExternalStorageDirectory().getPath() + "myFolderForBothApplications/myFileNameForBothApplications.txt";
Where myFolderForBothApplications and myFileNameForBothApplications can be replaced by your folder/filename, but this needs to be the same name in both applications.
Environment.getExternalStorageDirectory() returns a File-Object to the common, usable file-directory of the device, the same folder the user can see too.
By calling the getPath() method, a String representing the path to this storage is returned, so you can add your folder/filenames afterwards.
So a full code example would be:
String path = Environment.getExternalStorageDirectory().getPath() + "myFolderForBothApplications/";
String pathWithFile = path + "myFileNameForBothApplications.txt";
File dir = new File(path);
if(!dir.exists()) { //If the directory is not created yet
if(!dir.mkdirs()) { //try to create the directories to the given path, the method returns false if the directories could not be created
//Make some error-output here
return;
}
}
File file = new File(pathWithFile);
try {
f.createNewFile();
} catch (IOException e) {
e.printStackTrace();
//File couldn't be created
return;
}
Afterwards, you can write in the file or read from the file as provided e.g. in this answer.
Note that the file stored like this is visible for the user and my be edited / deleted by the user.
Also note what the JavaDoc for the getExternalStorageDirectory() says:
Return the primary external storage directory. This directory may not currently be accessible if it has been mounted by the user on their computer, has been removed from the device, or some other problem has happened. You can determine its current state with getExternalStorageState().
I do not know if this is the best/safest way to fix your problem, but it should work.
You can save the text file from your assets folder to anywhere in the sdcard, then you can read the file from the other application.
This method uses the getExternalFilesDir, that returns the absolute path to the directory on the primary shared/external storage device where the application can place persistent files it owns. These files are internal to the applications, and not typically visible to the user as media.
private void copyAssets() {
AssetManager assetManager = getAssets();
String[] files = null;
try {
files = assetManager.list("");
} catch (IOException e) {
Log.e("tag", "Failed to get asset file list.", e);
}
if (files != null) for (String filename : files) {
InputStream in = null;
OutputStream out = null;
try {
in = assetManager.open(filename);
File outFile = new File(Environment.getExternalStorageDirectory(), filename);
out = new FileOutputStream(outFile);
copyFile(in, out);
} catch(IOException e) {
Log.e("tag", "Failed to copy asset file: " + filename, e);
}
finally {
if (in != null) {
try {
in.close();
} catch (IOException e) {
// NOOP
}
}
if (out != null) {
try {
out.close();
} catch (IOException e) {
// NOOP
}
}
}
}
}
private void copyFile(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int read;
while((read = in.read(buffer)) != -1){
out.write(buffer, 0, read);
}
}
And to read:
File dir = Environment.getExternalStorageDirectory();
File yourFile = new File(dir, "path/to/the/file/inside/the/sdcard.ext");
I want to be able to open a PDF file when the user clicks on 'HELP' in my application. The PDF file is located with the JAR, extracted to a tmp directory and then selected to open by awt.Desktop.getDesktop () (to allow for windows and linux use).
When I run the app from Eclipse then it works fine, the PDF opens with no errors. When I export to JAR and run then I get an error stating the 'PDF document is damaged', if I navigate manually to the PDF document (on my ubuntu machine /tmp/546434564.pdf) then I get the same error when I try to open the file. I am confused what is going on. The file size of the 'damaged' PDF is the same as the working one, so I dont think it is a permission issue.
The code I am using is:
public Main() throws FontFormatException, IOException {
//lets load the font
Font font = Font.createFont(Font.TRUETYPE_FONT, this.getClass().getResourceAsStream("/Coalition_v2.ttf")).deriveFont(Font.PLAIN, 14);
System.out.println(font);
//lets write the tmp file for help to the machine now
try {
java.io.InputStream iss = getClass().getResourceAsStream("/nullpdf.pdf"); //update the filename here when the help guide is written
byte[] data = new byte[iss.available()];
iss.read(data);
iss.close();
String tempFile = "file";
File temp = File.createTempFile(tempFile, ".pdf");
FileOutputStream fos = new FileOutputStream(temp);
fos.write(data);
fos.flush();
fos.close();
tmphelpfile = temp.getAbsolutePath();
System.out.println(tmphelpfile);
} catch (IOException ex) {
ex.printStackTrace();
System.out.println("TEMP FILE NOT CREATED - ERROR in tmp file writing");
}
And then to call the pdf:
JMenu mnHelpGuide = new JMenu("Help Guide");
mnHelpGuide.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
// Help();
Desktop d = java.awt.Desktop.getDesktop ();
try {
System.out.println(tmphelpfile);
d.open (new java.io.File (String.valueOf(tmphelpfile)));
} catch (IOException e1) {
// TODO Auto-generated catch block
System.out.println("Couldnt open your file - error on HELP Guide");
e1.printStackTrace();
}
}
});
Thanks for the help guys. The problem was fixed by importing the ApachecommonsIO jar and then modifying the code to this:
try {
java.io.InputStream iss = getClass().getResourceAsStream("/nullpdf.pdf"); //update the filename here when the help guide is written
// byte[] data = new byte[iss.available()];
byte[] data = IOUtils.toByteArray(iss);
iss.read(data);
iss.close();
String tempFile = "file";
File temp = File.createTempFile(tempFile, ".pdf");
FileOutputStream fos = new FileOutputStream(temp);
fos.write(data);
fos.flush();
fos.close();
tmphelpfile = temp.getAbsolutePath();
System.out.println(tmphelpfile);
} catch (IOException ex) {
ex.printStackTrace();
System.out.println("TEMP FILE NOT CREATED - ERROR in tmp file writing");
}
I have a Java form in which you can select a file to open. I have that file:
File my_file = ...
I want to be able to save my file as a different name.
how can I do it using "File my_file"?
I tried:
File current_file = JPanel_VisualizationLogTab.get_File();
String current_file_name = current_file.getName();
//String current_file_extension = current_file_name.substring(current_file_name.lastIndexOf('.'), current_file_name.length()).toLowerCase();
FileDialog fileDialog = new FileDialog(new Frame(), "Save", FileDialog.SAVE);
fileDialog.setFile(current_file_name);
fileDialog.setVisible(true);
But that doesn't save the file.
I would recommend using the Apache Commons IO library to make this task easier. With this library, you could use the handy FileUtils class that provides many helper functions for handling file IO. I think you would be interested in the copy(File file, File file) function
try{
File current_file = JPanel_VisualizationLogTab.get_File();
File newFile = new File("new_file.txt");
FileUtils.copyFile(current_file, newFile);
} catch (IOException e){
e.printStackTrace();
}
Documentation
If you want to copy it with a different name, i found this piece of Code via google
public static void copyFile(File in, File out) throws IOException {
FileChannel inChannel = new FileInputStream(in).getChannel();
FileChannel outChannel = new FileOutputStream(out).getChannel();
try {
inChannel.transferTo(0, inChannel.size(), outChannel);
} catch (IOException e) {
throw e;
} finally {
if (inChannel != null)
inChannel.close();
if (outChannel != null)
outChannel.close();
}
}
now you can call it with
File inF = new File("/home/user/inputFile.txt");
File outF = new File("/home/user/outputFile.txt");
copyFile(inF, outF);
it´s just important that both Files exist, otherswise it will raise an exception
You can rename the file name.
Use:
myfile.renameTo("neeFile")
There is a Method called renameTo(new File("whatever you want")); for File Objects