Develop Reference

how to decode/ get encoding of file (Power BI desktop file)

I am having power BI desktop report(pbix) internal file (DataMashup), which i am trying to decode.
My Aim is to create Power-BI desktop report, Data Model using any programming language. I am using Java for initial.
files are encoded with some encoding technique.
I tried to get encoding of file and it is returning windows 1254. but decoding is not happening.
File f = new File("example.txt");
String[] charsetsToBeTested = {"UTF-8", "windows-1254", "ISO-8859-7"};
CharsetDetector cd = new CharsetDetector();
Charset charset = cd.detectCharset(f, charsetsToBeTested);
if (charset != null) {
try {
InputStreamReader reader = new InputStreamReader(new FileInputStream(f), charset);
int c = 0;
while ((c = reader.read()) != -1) {
System.out.print((char)c);
}
reader.close();
} catch (FileNotFoundException fnfe) {
fnfe.printStackTrace();
}catch(IOException ioe){
ioe.printStackTrace();
}
}else{
System.out.println("Unrecognized charset.");
}
Unzipping of file is also not working
public void unZipIt(String zipFile, String outputFolder)
{
byte buffer[] = new byte[1024];
try
{
File folder = new File(outputFolder);
if(!folder.exists())
{
folder.mkdir();
}
ZipInputStream zis = new ZipInputStream(new FileInputStream(zipFile));
System.out.println(zis);
System.out.println(zis.getNextEntry());
for(ZipEntry ze = zis.getNextEntry(); ze != null; ze = zis.getNextEntry())
{
String fileName = ze.getName();
System.out.println(ze);
File newFile = new File((new StringBuilder(String.valueOf(outputFolder))).append(File.separator).append(fileName).toString());
System.out.println((new StringBuilder("file unzip : ")).append(newFile.getAbsoluteFile()).toString());
(new File(newFile.getParent())).mkdirs();
FileOutputStream fos = new FileOutputStream(newFile);
int len;
while((len = zis.read(buffer)) > 0)
{
fos.write(buffer, 0, len);
}
fos.close();
}
zis.closeEntry();
zis.close();
System.out.println("Done");
}
catch(IOException ex)
{
ex.printStackTrace();
}
}

The file contains a binary header and then XML with UTF-8 specified.
The header data seems to hold the file name (Config/Package.xml), so assuming a zip format is understandable. With a zip format also there would be binary data at the end of file.
Maybe the file was downloaded using FTP, and a text conversion ("\n" to "\r\n") was done. Then the zip would be corrupted. Renaming the file to .zip might help testing the file with zip tools.
Try first the .tar format. This would be logical as the XML file is not compressed. Add .tar to the file ending.
Otherwise, if the content is always UTF-8 XML:
Path f = Paths.get("example.txt");
String start ="<?xml";
String end = ">";
byte[] bytes = Files.readAllBytes(f);
String s = new String(bytes, StandardCharsets.ISO_8859_1); // Single byte encoding.
int startI = s.indexOf(start);
int endI = s.lastIndexOf(end) + end.length();
//bytes = Arrays.copyOfRange(bytes, startI, endI);
String xml = new String(bytes, startI, endI - startI, StandardCharsets.UTF_8);

You can use the System.IO.Packaging library to extract the Power BI data mashup. It uses the OPC package standard, see here.

How to create a ZIP InputStream in Android without creating a ZIP file first?

I use NanoHTTPD as web server in my Android APP, I hope to compress some files and create a InputStream in server side, and I download the InputStream in client side using Code A.
I have read Code B at How to zip and unzip the files?, but how to create a ZIP InputStream in Android without creating a ZIP file first?
BTW, I don't think Code C is good way, because it make ZIP file first, then convert ZIP file to FileInputStream , I hope to create a ZIP InputStream directly!
Code A
private Response ActionDownloadSingleFile(InputStream fis) {
Response response = null;
response = newChunkedResponse(Response.Status.OK, "application/octet-stream",fis);
response.addHeader("Content-Disposition", "attachment; filename="+"my.zip");
return response;
}
Code B
public static void zip(String[] files, String zipFile) throws IOException {
BufferedInputStream origin = null;
ZipOutputStream out = new ZipOutputStream(new BufferedOutputStream(new FileOutputStream(zipFile)));
try {
byte data[] = new byte[BUFFER_SIZE];
for (int i = 0; i < files.length; i++) {
FileInputStream fi = new FileInputStream(files[i]);
origin = new BufferedInputStream(fi, BUFFER_SIZE);
try {
ZipEntry entry = new ZipEntry(files[i].substring(files[i].lastIndexOf("/") + 1));
out.putNextEntry(entry);
int count;
while ((count = origin.read(data, 0, BUFFER_SIZE)) != -1) {
out.write(data, 0, count);
}
}
finally {
origin.close();
}
}
}
finally {
out.close();
}
}
Code C
File file= new File("my.zip");
FileInputStream fis = null;
try
{
fis = new FileInputStream(file);
} catch (FileNotFoundException ex)
{
}

ZipInputStream as per the documentation ZipInputStream
ZipInputStream is an input stream filter for reading files in the ZIP file format. Includes support for both compressed and uncompressed entries.
Earlier I answered to this question in a way that it is not possible using ZipInputStream. I am Sorry.
But after investing some time I found that it is possible as per the below code
It is very much obvious that since you are sending files in zip format
over the network.
//Create proper background thread pool. Not best but just for solution
new Thread(new Runnable() {
#Override
public void run() {
// Moves the current Thread into the background
android.os.Process.setThreadPriority(android.os.Process.THREAD_PRIORITY_BACKGROUND);
HttpURLConnection httpURLConnection = null;
byte[] buffer = new byte[2048];
try {
//Your http connection
httpURLConnection = (HttpURLConnection) new URL("https://s3-ap-southeast-1.amazonaws.com/uploads-ap.hipchat.com/107225/1251522/SFSCjI8ZRB7FjV9/zvsd.zip").openConnection();
//Change below path to Environment.getExternalStorageDirectory() or something of your
// own by creating storage utils
File outputFilePath = new File ("/mnt/sdcard/Android/data/somedirectory/");
ZipInputStream zipInputStream = new ZipInputStream(new BufferedInputStream(httpURLConnection.getInputStream()));
ZipEntry zipEntry = zipInputStream.getNextEntry();
int readLength;
while(zipEntry != null){
File newFile = new File(outputFilePath, zipEntry.getName());
if (!zipEntry.isDirectory()) {
FileOutputStream fos = new FileOutputStream(newFile);
while ((readLength = zipInputStream.read(buffer)) > 0) {
fos.write(buffer, 0, readLength);
}
fos.close();
} else {
newFile.mkdirs();
}
Log.i("zip file path = ", newFile.getPath());
zipInputStream.closeEntry();
zipEntry = zipInputStream.getNextEntry();
}
// Close Stream and disconnect HTTP connection. Move to finally
zipInputStream.closeEntry();
zipInputStream.close();
} catch (IOException e) {
e.printStackTrace();
}finally {
// Close Stream and disconnect HTTP connection.
if (httpURLConnection != null) {
httpURLConnection.disconnect();
}
}
}
}).start();

What is the accurate way to read/download a file from the server (in Java)?

In my client-server application I have used a command (GET filename)to download a file into the client side. I have used the build in read() method to read the file. My teachers said it's not a very good practice to implement this read method. The reason is either it doesn't tell how exactly the file is reading from the server or it somehow is not able to download dynamic (large) file size. But at the moment I see that it's working fine. Since I am still in intermediate level in java, I need to learn the best way to do this job. How it could be improved in coding? That is I want to improve the while looping part in ClientSide.
I have pasted the relevent code:
ClientSide:
............
............
if (request.startsWith("GET")) {
File file = new File(request.substring(4));
is = socket.getInputStream();
fos = new FileOutputStream(file);
byte[] buffer = new byte[socket.getReceiveBufferSize()];
int bytesReceived = 0;
while ((bytesReceived = is.read(buffer)) >=0) {
//while ((bytesReceived = is.read(buffer))>=buffer) {
fos.write(buffer, 0, bytesReceived);
}
request = "";
fos.close();
is.close();
}
.................
.................
ServerSide:
.................
.................
else if (request.startsWith("GET")) {
System.out.println("");
String filename = request.substring(4);
File file = new File(System.getProperty("user.dir"));
File[] files = file.listFiles();
if (fileExists(files, filename)) {
file = new File(filename);
int fileSize = (int) file.length();
outputToClient.print("Status OK\r\n"
+ "Size " + fileSize + "KB" + "\r\n"
+ "\r\n"
+ "File " + filename + " Download was successfully\r\n");
outputToClient.flush();
// reading files
fis = new FileInputStream(file);
os = socket.getOutputStream();
byte[] buffer = new byte[2^7-1];
int bytesRead = 0;
while ((bytesRead = fis.read(buffer))!= -1) {
os.write(buffer, 0, bytesRead);
}
os.close();
fis.close();
} else {
outputToClient.print("Status 400\r\n"
+ "File " + filename + " not found\r\n"
+ "\r\n");
outputToClient.flush();
}
}
outputToClient.flush();
}
.................
.................

You need to consume the rest of the HTTP response headers, by reading until you get a blank line, if you haven't already done that.
Apart from that, your code looks fine to me, except that I would use a much bigger buffer than 127, at least 8192, possibly a multiple of that.
Ask your teacher what (on earth) he's talking about.

SmbFileOutputStream write creating corrupted jpg files

I'm using JCIFS SmbFileOutputStream write to upload jpg (and mp4) files to a share on a local Windows network. While this works well most of the time, I sometimes find that the resulting files are corrupt - e.g. if it's a jpg perhaps only the top part of the photo will be legible/visible.
I have the upload in a try/catch block, but it is not throwing an exception. Is there any way that I can verify that a file has been uploaded correctly?
try {
if (debugging_on) {
logger.info("UploadService.011 UploadFiles: uploading file:" + destFileName);
}
SmbFileOutputStream sfos = new SmbFileOutputStream(sFile);
FileInputStream fileInputStream = new FileInputStream(new File(
sSourceFilePath));
byte[] buf = new byte[16 * 1024 * 1024];
int len;
while ((len = fileInputStream.read(buf)) > 0) {
sfos.write(buf, 0, len);
}
fileInputStream.close();
sfos.close();
// Update the database to include the date/time of this upload
millisStart = Calendar.getInstance().getTimeInMillis();
sql = "UPDATE upload_history SET file_uploaded_date = "
+ millisStart + " WHERE filename = '" + filename + "'";
db.execSQL(sql);
} catch (Exception e) {
mNotifyBuilder.setContentText("Upload error - check folder permissions");
mNotificationManager.notify(1, mNotifyBuilder.build());
return "WriteFailure";

sfos.close();
needs to go before
fileInputStream.close();
Close the output before you close the input,
Adding 'sfos.flush()' couldn't hurt.

Java Connecting URL and downloading a zip but when extracting the zip it's not properly downloaded

I am sending a request XML to the URL and receiving a zip file to the given path.
Sometimes I'm facing troubles when the bandwidth is low this zip file, most likely 120MB size is not getting downloaded properly. And getting an error when extracting the zip file. Extracting happens from the code as well. When I download in high bandwidth this file gets download without issue.
I'm looking for a solution without making the bandwidth high, from program level are there any ways to download this zip file, may be part by part or something like that? Or anyother solution that you all are having is highly appreciated.
Downloading :
url = new URL(_URL);
sc = (HttpURLConnection) url.openConnection();
sc.setDoInput(true);
sc.setDoOutput(true);
sc.setRequestMethod("POST");
sc.connect();
OutputStream mOstr = sc.getOutputStream();
mOstr.write(request.getBytes());
InputStream in = sc.getInputStream();
FileOutputStream out = new FileOutputStream(path);
int count;
byte[] buffer = new byte[86384];
while ((count = in.read(buffer,0,buffer.length)) > 0)
out.write(buffer, 0, count);
out.close();
Extracting :
try {
ZipFile zipFile = new ZipFile(path+zFile);
Enumeration<?> enu = zipFile.entries();
while (enu.hasMoreElements()) {
ZipEntry zipEntry = (ZipEntry) enu.nextElement();
String name = path+"/data_FILES/"+zipEntry.getName();
long size = zipEntry.getSize();
long compressedSize = zipEntry.getCompressedSize();
System.out.printf("name: %-20s | size: %6d | compressed size: %6d\n", name, size, compressedSize);
File file = new File(name);
if (name.endsWith("/")) {
file.mkdirs();
continue;
}
File parent = file.getParentFile();
if (parent != null) {
parent.mkdirs();
}
InputStream is = zipFile.getInputStream(zipEntry);
FileOutputStream fos = new FileOutputStream(file);
byte[] bytes = new byte[86384];
int length;
while ((length = is.read(bytes)) >= 0) {
fos.write(bytes, 0, length);
}
is.close();
fos.close();
}
zipFile.close();
} catch (Exception e) {
log("Error in extracting zip file ");
e.printStackTrace();
}