I'm developing an APP that needs to download a file from the Internet and store it on the SDCard.
I've noticed that some devices report errors while downloading, such as "Parsing Error". I'm assuming that some devices don't have SDCard or the path that I'm getting in my class isn't correct. What's the safest approach to support all devices if there's no SDCard or isn't mounted ?
This is my code:
/**
* Downloading file in background thread
* */
#Override
protected String doInBackground(String... f_url) {
int count;
try {
URL url = new URL(f_url[0]);
URLConnection conection = url.openConnection();
conection.connect();
// getting file length
int lenghtOfFile = conection.getContentLength();
// input stream to read file - with 8k buffer
InputStream input = new BufferedInputStream(url.openStream(), 8192);
// Output stream to write file
OutputStream output = new FileOutputStream(Environment.getExternalStorageDirectory().getPath()+"/Download/file.apk");
byte data[] = new byte[1024];
long total = 0;
while ((count = input.read(data)) != -1) {
total += count;
// publishing the progress....
// After this onProgressUpdate will be called
publishProgress(""+(int)((total*100)/lenghtOfFile));
// writing data to file
output.write(data, 0, count);
}
// flushing output
output.flush();
// closing streams
output.close();
input.close();
} catch (Exception e) {
Log.e("Error: ", e.getMessage());
}
return null;
}
I think the problem may be on this line:
OutputStream output = new FileOutputStream(Environment.getExternalStorageDirectory().getPath()+"/Download/file.apk");
Should I use the getExternalStorageDirectory() and download ? or is there any "safest" location that is common to all devices ?
First, you don't want to use AsyncTask to download a file. Because if the user kills that screen that hosts the Task, the download will be killed too. Look into IntentService.
Second, familiarize yourself with the Android code examples here: http://developer.android.com/guide/topics/data/data-storage.html#filesExternal
You can check for what's available and then get the appropriate directory.
Related
I am trying to allow a user to download a file (attachment) using Java to serve up the download. I have been partially successful. The file is read, and on the client side there is a prompt for a download. A file is saved successfully, but it has 0 bytes. Here is my server side code:
String stored = "/var/lib/tomcat/webapps/myapp/attachments/" + request.getParameter("stored");
String realname = request.getParameter("realname");
// Open the input and output streams
FileInputStream attachmentFis = new FileInputStream(stored);
FileOutputStream attachmentFos = new FileOutputStream(realname);
try {
// Send the file
byte[] attachmentBuffer = new byte[1024];
int count = 0;
while((count = attachmentFis.read(attachmentBuffer)) != -1) {
attachmentFos.write(attachmentBuffer, 0, count);
}
} catch (IOException e) {
// Exception handling
} finally {
// Close the streams
attachmentFos.flush();
attachmentFos.close();
attachmentFis.close();
}
For context, this is in a servlet. The files have an obfuscated name, which is passed as "stored" here. The actual file name, the name the user will see, is "realname".
What do I need to do to get the actual file to arrive at the client end?
EDIT
Following suggestions in the comments, I changed the write to include the 0, count parameters and put the close stuff in a finally block. However, I am still getting a 0 byte file when I attempt a download.
EDIT 2
Thanks to the logging suggestion from Dave the Dane, I discovered the file was being written locally. A bit of digging and I found I needed to use response.getOutputStream().write instead of a regular FileOutputStream. I have been successful in getting a file to download through this method. Thank you all for your helpful suggestions.
As others have observed, you'd be better off using try-with-resources & let that handle the closing.
Assuming you have some Logging Framework available, maybe the following would cast light on the matter...
try {
LOG.info ("Requesting....");
final String stored = "/var/lib/tomcat/webapps/myapp/attachments/" + request.getParameter("stored");
LOG.info ("stored.......: {}", stored);
final String realname = request.getParameter("realname");
LOG.info ("realname.....: {}", realname);
final File fileStored = new File(stored);
LOG.info ("fileStored...: {}", fileStored .getCanonicalPath());
final File fileRealname = new File(realname);
LOG.info ("fileRealname.: {}", fileRealname.getCanonicalPath());
try(final InputStream attachmentFis = new FileInputStream (fileStored);
final OutputStream attachmentFos = new FileOutputStream(fileRealname))
{
final byte[] attachmentBuffer = new byte[64 * 1024];
int count;
while((count = attachmentFis.read (attachmentBuffer)) != -1) {
; attachmentFos.write(attachmentBuffer, 0, count);
LOG.info ("Written......: {} bytes to {}", count, realname);
}
attachmentFos.flush(); // Probably done automatically in .close()
}
LOG.info ("Done.");
}
catch (final Exception e) {
LOG.error("Problem!.....: {}", request, e);
}
If it won't reach the finally block, you should stop ignoring the IOException which is being thrown:
catch (IOException e) {
// Exception handling
System.err.println(e.getMessage());
}
I'd asssume that the realname is just missing an absolute path.
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();
}
I'm working on an app that records video and I need to send already written data in videofile to server in base64 string without stopping record process. Does anyone know how to make it with less memory consumption?
For now I'm doing it this way
private void sendNewVideos(String path) {
try {
Log.i(TAG, "VIDEO PATH - " + path);
FileWriter fileWriter = new FileWriter(new File(pathToFolder + "/temp.txt"));
String base64String = new String();
File file = new File(path);
Long size = 0L;
base64String = Base64.encodeToString(readFile(file, size), Base64.DEFAULT);
fileWriter.append(base64String);
fileWriter.flush();
boolean flag = true;
while (flag) {
if (size < file.length()) {
base64String = Base64.encodeToString(readFile(file, size), Base64.DEFAULT);
fileWriter.append(base64String);
fileWriter.flush();
size = file.length();
}
}
fileWriter.close();
} catch (IOException e) {
e.printStackTrace();
}
}
private byte[] readFile(File file, Long size) {
try {
RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");
randomAccessFile.seek(size);
FileChannel fileChannel = randomAccessFile.getChannel();
ByteBuffer buffer = ByteBuffer.allocate(1024 * 1024 * 2);
while (fileChannel.read(buffer) > 0) {
buffer.flip();
byte[] temp = new byte[buffer.limit()];
for (int i = 0; i < buffer.limit(); i++) {
temp[i] = buffer.get(i);
}
buffer.clear();
return temp;
}
fileChannel.close();
randomAccessFile.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
Writing to file is just to check how it works. But after some time recording stops. Sometimes LogCat shows something like this
I/art: Thread[3,tid=23425,WaitingInMainSignalCatcherLoop,Thread*=0x7fe42c410800,peer=0x22c08080,"Signal Catcher"]: reacting to signal 3
I/art: Wrote stack traces to '/data/anr/traces.txt'
I think that's because of either memory leak or just out of memory problem.
Some kind of solutions.
Don't use Base64 for encoding video for sending via network (even wi-fi) as it increases amount of data approximately 10 times which is not very good for battery and could kill or hang you process/service.
Avoid reading file that is in process of written as it could and would slowdown IO operation speed.
If you still need to send data from such file use some kind of next algorithm:
get access to file (for example with buffered input stream);
read part of file to buffer;
do as simpler work with it as possible. For, example, send buffer to server in separate thread with HTTPUrlConnection. You can find example here.
Control used memory otherwise system try to kill you process.
I'm doing some stuff on an Arm linux device, specifically (FriendlyArm 2440).
I open the cmos camera ("/dev/camera")
How can I convert it to a video / photo file?
my current code is like this:
FileInputStream fis = null;
try {
String file = "/dev/camera";
fis = new FileInputStream(file);
byte[] buffer = new byte[1024];
int count = fis.read(buffer);
while (count != -1) {
System.out.println(buffer);
count = fis.read(buffer);
}
} catch (IOException ex) {
System.out.println("Error: " + ex.getMessage());
} finally {
try {
fis.close();
} catch (IOException ex) {
System.out.println("Error: " + ex.getMessage());
}
}
Finally I want to send the data via socket to a client program on the PC and save the file over there or just display the live stream.
What technique or library should I use to save as video /photo?
I would recommend looking into the gstreamer package. Not certain if your FriendlyArm 2440 board supports gstreamer, but you might be able to cross compile and add gstreamer yourself. Then you can create a custom plugin to support your camera, then use the many available plugins to generate/encode and stream video from the board... assuming you have the CPU resources.
You could also use gstreamer on the receiving PC side to receive and display or process the video/photos. That might also be a possibility: stream the raw video to the PC, and have the PC process it ( but that clearly requires more network bandwidth ).
Good luck,
I was browsing the Internet for random Java code, and I found this source code for a download manager. It uses RandomAccessFile to download the files. The one thing I could not figure out though, was where it would download to. Here is the method that downloads the file:
public void startDownload() {
System.out.println("Starting...");
RandomAccessFile file = null;
InputStream stream = null;
try {
URL downloadLink = new URL("http://www.website.com/file.txt");
// Open the connection to the URL
HttpURLConnection connection = (HttpURLConnection) downloadLink.openConnection();
// Specify what portion of file to download
connection.setRequestProperty("Range", "bytes=" + downloaded + "-");
// Connect to the server
connection.connect();
// Make sure the code is in the 200 range
if (connection.getResponseCode() / 100 != 2) {
error();
}
// Check for valid content length
int contentLength = connection.getContentLength();
if (contentLength < 1) {
error();
}
// Set the size for the download if it hasn't been already set
if (size == -1) {
size = contentLength;
stateChanged();
}
// Open file and seek to the end of it
file = new RandomAccessFile(getFileName(downloadLink), "rw");
// getFileName returns the name of the file mentioned in the URL
file.seek(downloaded);
stream = connection.getInputStream();
while (status == DOWNLOADING) {
System.out.println("Progress: " + getProgress() + "%");
// Size the buffer according to how much of the file is left to download
byte buffer[];
if (size - downloaded > MAX_BUFFER_SIZE) {
buffer = new byte[MAX_BUFFER_SIZE];
} else {
buffer = new byte[size - downloaded];
}
// Read from the server into the buffer
int read = stream.read(buffer);
if (read == -1) {
break;
}
// Write buffer to file
file.write(buffer, 0, read);
downloaded += read;
stateChanged();
}
if (status == DOWNLOADING) {
status = COMPLETE;
stateChanged();
}
} catch (Exception e) {
error();
} finally {
// Close the stream and RAF
}
System.out.println("Done!");
}
I am sorry if this is obvious. I am new to the RandomAccessFile class, as I just learned of it today.
It will download it in the current working directory (i.e. where you run your java command) and the name of the file will be given by getFileName(downloadLink).
I am new to this too. getFileName appears to be a method within the same class and that code is missing.