Develop Reference

Android FileOutputStream Seems to Fail

I am trying to transfer a video file from an RPi hotspot to my a directory on my phone over WiFi. I have been able to successfully create a folder in my storage, connect with the RPi server, and receive data. However, the file that appears after being written isn't correct. In fact, when I try to open it, it just opens a separate, unrelated app on my phone. Very weird!
Here is the code in question:
try {
BufferedInputStream myBis = new BufferedInputStream(mySocket.getInputStream());
DataInputStream myDis = new DataInputStream(myBis);
byte[] videoBuffer = new byte[4096*2];
int i = 0;
while (mySocket.getInputStream().read(videoBuffer) != -1) {
Log.d(debugStr, "while loop");
videoBuffer[videoBuffer.length-1-i] = myDis.readByte();
Log.d(debugStr, Arrays.toString(videoBuffer));
i++;
}
Log.d(debugStr, "done with while loop");
// create a File object for the parent directory
File testDirectory = new File(Environment.getExternalStorageDirectory()+File.separator, "recordFolder");
Log.d(debugStr, "path made?");
if(!testDirectory.exists()){
testDirectory.mkdirs();
}
Log.d(debugStr, "directory made");
// create a File object for the output file
File outputFile = new File(testDirectory.getPath(), "recording1");
Log.d(debugStr, "outputfile made");
// now attach the OutputStream to the file object, i
FileOutputStream fileOutputStream = new FileOutputStream(outputFile);
Log.d(debugStr, "write to file object made");
fileOutputStream.write(videoBuffer);
Log.d(debugStr, "video written");
fileOutputStream.close();
Log.d(debugStr, "done");
} catch (IOException e1) {
e1.printStackTrace();
}
The video is initially in .h264 format and is being sent as a byte array. The file is 10MB in size. In my while loop, I print out the value of the array as a string, and it prints a lot of data. Enough data for me to suspect that all the data is being sent. When I navigate to the folder it should be in, there is a file with the name I gave it, "recording1", but it is only 8KB in size.
Any ideas on what is going on? Any help is greatly appreciated!

Android FileOutputStream seems to fail
No it doesn't. Your code seems to fail. That's because your code makes no sense. You're throwing away large chunks of data, more or less accumulating only 1 out of every 8192 bytes; you're using both buffered and unbuffered reads; you're limiting the input to 8192 bytes; and you're never closing the input. And if the input is larger than 8192*8193 you can get an ArrayIndexOutOfBoundsException.
Throw it all away and use this:
try {
File testDirectory = new File(Environment.getExternalStorageDirectory()+File.separator, "recordFolder");
if(!testDirectory.exists()){
testDirectory.mkdirs();
}
File outputFile = new File(testDirectory, "recording1");
try (OutputStream out = new BufferedOutputStream(new FileOutputStream(outputFile));
BufferedInputStream in = new BufferedInputStream(mySocket.getInputStream())) {
byte[] buffer = new byte[8192]; // or more, whatever you like > 0
int count;
// Canonical Java copy loop
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
}
} catch (IOException e1) {
e1.printStackTrace();
}

Setting permissions for created directory to copy files into it

During the execution of my program it creates a directory which contains two sub-directories/two folders. Into one of these folders I need to copy a Jar-File. My programm resembles an installation routine. The copying of the Jar file is not the problem here, but the permissions of the created directories.
I tried to set the permissions of the directories (before actually creating them with the mkdirs() method) with File.setWritable(true, false) and also with the .setExecutable and .setReadable methods, but the access to the sub-directories is still denied.
Here's an excerpt of my code for the creation of one of the two sub-directories:
folderfile = new File("my/path/to/directory");
folderfile.setExecutable(true, false);
folderfile.setReadable(true, false);
folderfile.setWritable(true, false);
result = folderfile.mkdirs();
if (result) {
System.out.println("Folder created.");
}else {
JOptionPane.showMessageDialog(chooser, "Error");
}
File source = new File("src/config/TheJar.jar");
File destination = folderfile;
copyJar(source, destination);
And my "copyJar" method:
private void copyJar(File source, File dest) throws IOException {
InputStream is = null;
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer))>0) {
os.write(buffer, 0, length);
}
} catch (Exception e) {
e.printStackTrace();
}
is.close();
os.close();
}
At os = new FileOutputStream(dest); the debugger throws a FileNotFoundException with the description that the access to the directory has been denied.
Does anyone have an idea what I am doing wrong or have a better solution for setting the permissions via Java? Thanks in advance!

A similar question was asked there are several years.
A possible solution for Java 7 and Unix system is available here : How do i programmatically change file permissions?
Or, below the best response, a example with JNA.
I hope that that will help you !

I solved the problem. In the end it was much easier to solve than expected.
The main problem was not the permission issue but the FileNotFoundException. The file that is assigned to the OutputStream is not really a file, but just a directory so that the Stream can't find it. You have to create the file before initializing the OutputStream and after that you copy your source file into the newly created file. The code:
private void copyJar(File source, File dest) throws IOException {
InputStream is = null;
File dest2 = new File(dest+"/TheJar.jar");
dest2.createNewFile();
OutputStream os = null;
try {
is = new FileInputStream(source);
os = new FileOutputStream(dest2);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer))>0) {
os.write(buffer, 0, length);
}
} catch (Exception e) {
e.printStackTrace();
}
is.close();
os.close();
}

Copying file from network into local directory

I want to copy a file from network location into my local directory. I have written following code for this, but the problem is, it needs to have a file created first, and then the out stream writes the bytes stream into this file.
What i want is, the precondition to first create file locally should not be there. It should simply copy the network file into the mentioned directory directly, thats it! I'm kind of doing this for the first time.
try {
File srcFile = new File("//network//file//path//here");
File dstFileName = new File("//local//drive//file//path//here");
InputStream in = new FileInputStream(srcFile);
OutputStream out = new FileOutputStream(dstFileName);
byte[] buff = new byte[1024];
int length;
while ((length = in.read(buff)) > 0) {
out.write(buff, 0, length);
}
in.close();
out.close();
} catch (Exception ex) {
ex.printStackTrace();
}

You need to create the file, before you can write to it.
if(!dstFileName.exists()){
dstFileName.createNewFile();
}
If the the path does not exist, you can try to create it first with
dstFileName.getParentFile().mkdirs();

Faster way of copying data in Java?

I have been given a task of copying data from a server. I am using BufferedInputStream and output stream to copy the data and I am doing it byte by byte. Even though it is running but It is taking ages to copy the data as some of them are in 100's MBs, so definitely it is not gonna work. Can anyone suggest me any alternate of Byte by Byte copy so that my code can copy file that are in few Hundred MBs.
Buffer is 2048.
Here is how my code look like:
static void copyFiles(SmbFile[] files, String parent) throws IOException {
SmbFileInputStream input = null;
FileOutputStream output = null;
BufferedInputStream buf_input = null;
try {
for (SmbFile f : files) {
System.out.println("Working on files :" + f.getName());
if (f.isDirectory()) {
File folderToBeCreated = new File(parent+f.getName());
if (!folderToBeCreated.exists()) {
folderToBeCreated.mkdir();
System.out.println("Folder name " + parent
+ f.getName() + "has been created");
} else {
System.out.println("exists");
}
copyFiles(f.listFiles(), parent + f.getName());
} else {
input = (SmbFileInputStream) f.getInputStream();
buf_input = new BufferedInputStream(input, BUFFER);
File t = new File(parent + f.getName());
if (!t.exists()) {
t.createNewFile();
}
output = new FileOutputStream(t);
int c;
int count;
byte data[] = new byte[BUFFER];
while ((count = buf_input.read(data, 0, BUFFER)) != -1) {
output.write(data, 0, count);
}
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (input != null) {
input.close();
}
if (output != null) {
output.close();
}
}
}

Here is a link to an excellent post explaining how to use nio channels to make copies of streams. It introduces a helper method ChannelTools.fastChannelCopy that lets you copy streams like this:
final InputStream input = new FileInputStream(inputFile);
final OutputStream output = new FileOutputStream(outputFile);
final ReadableByteChannel inputChannel = Channels.newChannel(input);
final WriteableByteChannel outputChannel = Channels.newChannel(output);
ChannelTools.fastChannelCopy(inputChannel, outputChannel);
inputChannel.close();
outputChannel.close()

Well since you're using a BufferedInputStream, you aren't reading byte by byte, but rather the size of the buffer. You could just try increasing the buffer size.

Reading/writing byte-by-byte is definitely going to be slow, even though the actual reading/writing is done by chunks of the buffer size. One way to speed it up is to read/write by blocks. Have a look at read(byte[] b, int off, int len) method of BufferedInputStream. However it probably won't give you enough of the improvement.
What would be much better is to use nio package (new IO) to copy data using nio channels. Have a look at nio documentation for more info.

I would suggest to use FileUtils from org.apache.commons.io. It has enough utility methods to perform file operations.
org.apache.commons.io.FileUtils API Here

Java unzip from URL misses 2kb on file

I am trying to unzip a file from the internet using the following code. On one of the files("uq.class"), after it has been unzipped from the online source, is missing about 2kb of file size(the original file is 10,084, unzipped I get 8,261). All the other files seem to be completely fine, and when I copy the uq.class file from the zip and place it in manually, it functions perfectly. Can anyone explain whats going on and provide a fix? Below is the unzipping portions of the code.
public static File unpackArchive(URL url, File targetDir) throws IOException {
if (!targetDir.exists()) {
targetDir.mkdirs();
}
InputStream in = new BufferedInputStream(url.openStream(), 2048);
// make sure we get the actual file
File zip = File.createTempFile("arc", ".zip", targetDir);
OutputStream out = new BufferedOutputStream(new FileOutputStream(zip),2048);
copyInputStream(in, out);
out.close();
return unpackArchive(zip, targetDir);
}
public static File unpackArchive(File theFile, File targetDir) throws IOException {
if (!theFile.exists()) {
throw new IOException(theFile.getAbsolutePath() + " does not exist");
}
if (!buildDirectory(targetDir)) {
throw new IOException("Could not create directory: " + targetDir);
}
ZipFile zipFile = new ZipFile(theFile);
for (Enumeration entries = zipFile.entries(); entries.hasMoreElements();) {
ZipEntry entry = (ZipEntry) entries.nextElement();
File file = new File(targetDir, File.separator + entry.getName());
if (!buildDirectory(file.getParentFile())) {
throw new IOException("Could not create directory: " + file.getParentFile());
}
if (!entry.isDirectory()) {
copyInputStream(zipFile.getInputStream(entry), new BufferedOutputStream(new FileOutputStream(file),2048));
} else {
if (!buildDirectory(file)) {
throw new IOException("Could not create directory: " + file);
}
}
}
zipFile.close();
theFile.delete();
return theFile;
}
public static void copyInputStream(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int len = in.read(buffer);
while (len >= 0) {
out.write(buffer, 0, len);
len = in.read(buffer);
}
in.close();
out.close();
}
public static boolean buildDirectory(File file) {
return file.exists() || file.mkdirs();
}

Cannot directly see anything wrong with the code at first sight. What I would recommend you doing however is closing your streams more safely. In your current implementation you close the in and out streams at the same time, close statements can cause exceptions as can read and write statements! If any one of those fails, your files will be left open and in time your application will run out of file descriptors. You're better off doing the closing in a finally statement, that way you're sure they get closed.

I don't know why I cant sign in, but I figured out the issue. I did the whole cart before the horse thing. I extracted the proper file, then extracted the old file over it, so I kept re-integrating the older file. 5 hours of programming out the window. Remember, kiddies, proper programming architecture saves you A TON of headaches.