I want to return file (read or load) from method and then remove this file.
public File method() {
File f = loadFile();
f.delete();
return f;
}
But when I delete a file, I delete it from disk and then exists only descriptor to non-existing file on return statement. So what is the most effective way for it.
You can't keep the File handle of deleted file, rather you can keep the data in a byte array temporarily, delete the file and then return the byte array
public byte[] method() {
File f =loadFile();
FileInputStream fis = new FileInputStream(f);
byte[] data = new byte[fis.available()];
fis.read(data);
f.delete();
return data;
}
// Edit Aproach 2
FileInputStream input = new FileInputStream(f);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buf = new byte[1024];
int bytesRead = input.read(buf);
while (bytesRead != -1) {
baos.write(buf, 0, bytesRead);
bytesRead = input.read(buf);
}
baos.flush();
byte[] bytes = baos.toByteArray();
you can construct the file data from byte array
However, my suggestion is to use IOUtils.toByteArray(InputStream input) from Jakarta commons, why do you want re write when already in plate
Assuming you want to return the file to the browser, this is how I did it :
File pdf = new File("file.pdf");
if (pdf.exists()) {
try {
InputStream inputStream = new FileInputStream(pdf);
httpServletResponse.setContentType("application/pdf");
httpServletResponse.addHeader("content-disposition", "inline;filename=file.pdf");
copy(inputStream, httpServletResponse.getOutputStream());
inputStream.close();
pdf.delete();
} catch (Exception e) {
e.printStackTrace();
}
}
private static int copy(InputStream input, OutputStream output) throws IOException {
byte[] buffer = new byte[512];
int count = 0;
int n = 0;
while (-1 != (n = input.read(buffer))) {
output.write(buffer, 0, n);
count += n;
}
return count;
}
Related
I have this part of function where it supposed to download file like pdf from server and store in new directory. It does do this but an empty pdf or text file.How to fix it.
`File urlfile = new File(host + "/" + path);
urlfile.getParentFile().mkdirs();
// create outputstream for request and inputstream for data
// download
FileOutputStream outS = new FileOutputStream(urlfile);
DataInputStream instream = new DataInputStream(newsocket.getInputStream());
// get rid of head part to get to actual file
String l = null;
String lastmodtime = null;
boolean done = false;
while (!(l = DAA.readLine()).equals("")) {
if (!done && l.contains("Last-Modified:")) {
lastmodtime = l.substring(l.indexOf(' ') + 1, l.length());
done = true;
System.out.println(l);
}
}
// read in bytes to correct file name
try {
byte[] inbytes = new byte[16384];
int input;
while ((input = instream.read(inbytes)) != -1) {
outS.write(inbytes, 0, input);
}
}`
You can try this simple code if you want to create a copy of the file or you can even use apache commons io (FileUtils.copyFile(source, dest)) for java copy file operation.
private static void copyFileUsingStream(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);
}
} finally {
is.close();
os.close();
}
}
I am creating one directory i.e file and storing the bitmap images into that file,now how to convert it into byte array
File myDir = new File(root + "/saved_images");
myDir.mkdirs();
Random generator = new Random();
int n = 10000;
n = generator.nextInt(n);
String fname = "Image-"+ n +".jpg";
File file = new File (myDir, fname);
if (file.exists ()) file.delete ();
try {
FileOutputStream out = new FileOutputStream(file);
bmp.compress(Bitmap.CompressFormat.JPEG, 90, out);
out.flush();
out.close();
} catch (Exception e) {
e.printStackTrace();
}
If you just want to modify your existing code to write the image to a byte array instead of a file, then replace the try block with this code:
ByteArrayOutputStream out = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.JPEG, 90, out);
bytes = out.getBytes();
... where bytes has type byte[], and get rid of the code that generates the filename and deletes the existing file if it exists. Since you writing to a ByteArrayOutputStream, there is not need to call flush() or close() on out. (They won't do anything.)
Not exactly sure what you're trying to do, but you can try something like:
InputStream is = ...
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
int nRead;
byte[] data = new byte[some huge number, power of 2 preferably];
while ((nRead = is.read(data, 0, data.length)) != -1) {
buffer.write(data, 0, nRead);
}
buffer.flush();
byte[] byteArray = buffer.toByteArray();
Just Use this to read the file where you kept.
// Returns the contents of the file in a byte array.
public static byte[] getBytesFromFile(File file) throws IOException {
InputStream is = new FileInputStream(file);
// Get the size of the file
long length = file.length();
// You cannot create an array using a long type.
// It needs to be an int type.
// Before converting to an int type, check
// to ensure that file is not larger than Integer.MAX_VALUE.
if (length > Integer.MAX_VALUE) {
// File is too large
}
// Create the byte array to hold the data
byte[] bytes = new byte[(int)length];
// Read in the bytes
int offset = 0;
int numRead = 0;
while (offset = 0) {
offset += numRead;
}
// Ensure all the bytes have been read in
if (offset
Courtesy : http://www.exampledepot.com
I have used this code for converting image file into byte araay,
Bitmap bm = BitmapFactory.decodeResource(getResources(),R.drawable.abc);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 40 , bos);
public byte[] bitmapdata = bos.toByteArray();
Log.w("Image Conversion", String.valueOf(bitmapdata.length));
String converted_txt="";
for (int i = 0; i < bitmapdata.length; i++)
{
Log.w("Image Conversion", String.valueOf(bitmapdata[i]));
ba = bitmapdata[i];
converted_txt=converted_txt+bitmapdata[i];
}
try
{
File myFile = new File("/sdcard/myImageToByteFile.jpg");
myFile.createNewFile();
fOut = new FileOutputStream(myFile);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
myOutWriter.write(ba);
myOutWriter.close();
fOut.close();
}
catch (Exception e)
{
Toast.makeText(getApplicationContext(), e.getMessage(),5000).show();
}
I have this code to read bytes to another file.
But I'm not able to concatenate two mp3 files into one.
Am I missing something?
public static void main(String[] args) {
String strFileName = ("D:/Music/Assb/Love.mp3");
BufferedOutputStream bos = null;
try
{
//create an object of FileOutputStream
FileOutputStream fos = new FileOutputStream(new File(strFileName));
//create an object of BufferedOutputStream
bos = new BufferedOutputStream(fos);
String str = "D:/Music/Assembled/Heart001.mp3"
+ "D:/Music/Assembled/Heart002.mp3";
/*
* To write byte array to file use,
* public void write(byte[] b) method of BufferedOutputStream
* class.
*/
System.out.println("Writing byte array to file");
bos.write(str.getBytes());
System.out.println("File written");
It`s suck. Mp3 file starts with headers. For correct merging you have to skip first 32 bytes. Try this.
try {
FileInputStream fistream1 = new FileInputStream(_file_name);
File f = new File(new File(_file_name).getParent()+"/final.mp3");
if(!f.exists())
{
f.createNewFile();
}
FileOutputStream sistream = new FileOutputStream((new File(_file_name)).getParent()+"/final.mp3");
int temp;
int size = 0;
temp = fistream1.read();
while( temp != -1)
{
sistream.write(temp);
temp = fistream1.read();
};
fistream1.close();
FileInputStream fistream2 = new FileInputStream(temp_file);
fistream2.read(new byte[32],0,32);
temp = fistream2.read();
while( temp != -1)
{
sistream.write(temp);
temp = fistream2.read();
};
fistream2.close();
sistream.close();
} catch (IOException e) {
e.printStackTrace();
}
You need to do this in two steps
String str = "D:/Music/Assembled/Heart001.mp3";
>>> ADD code to open the file given by str <<<<
bos.write(strFile.getBytes());
>>> Add code to close the file
str = "D:/Music/Assembled/Heart002.mp3";
>>> ADD code to open the file given by str <<<<
bos.write(strFile.getBytes());
>>> Add code to close the file
And as you can see you need code to open the mp3 file to read it
What Are You Trying For...Actually..if You Want To Read 2 Files to Byte Stream the dont String str = "D:/Music/Assembled/Heart001.mp3"
+ "D:/Music/Assembled/Heart002.mp3";
make str1=D:/Music/Assembled/Heart001.mp3 and str2=D:/Music/Assembled/Heart002.mp3 and read str1,str2 seperately through bufferedoutputsream
This code will work well and merge audio of similar type with in seconds...
try {
InputStream in = new FileInputStream("C:\\a.mp3");//firstmp3
byte[] buffer = new byte[1 << 20]; // loads 1 MB of the file
OutputStream os = new FileOutputStream(new File("C:\\output.mp3", true);//output mp3
int count;
while ((count = in.read(buffer)) != -1) {
os.write(buffer, 0, count);
os.flush();
}
in.close();
in = new FileInputStream("C:\\b.mp3");//second mp3
while ((count = in.read(buffer)) != -1) {
os.write(buffer, 0, count);
os.flush();
}
in.close();
os.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
I have byte[] of zip file. I have to unzip it without creating new file, and get byte[] of that unzip file.
Please help me to do that
You can use ZipInputStream and ZipOutputStream (in the package java.util.zip) to read and write from ZIP files.
If you have the data in a byte array, you can let these read from a ByteArrayInputStream or write to a ByteArrayOutputStream pointing to your input and output byte arrays.
public static List<ZipEntry> extractZipEntries(byte[] content) throws IOException {
List<ZipEntry> entries = new ArrayList<>();
ZipInputStream zipStream = new ZipInputStream(new ByteArrayInputStream(content));
ZipEntry entry = null;
while ((entry = zipStream.getNextEntry()) != null)
{
System.out.println( "entry: " + entry );
ZipOutputStream stream= new ZipOutputStream(new FileOutputStream(new File("F:\\ssd\\wer\\"+entry.getName())));
stream.putNextEntry(entry);
}
zipStream.close();
return entries;
}
In case you need to deflate your zipped data and you are too lazy to deal with the streams, you can use the following code:
public byte[] deflate(byte[] data) throws IOException, DataFormatException {
Inflater inflater = new Inflater();
inflater.setInput(data);
ByteArrayOutputStream outputStream = new ByteArrayOutputStream(data.length);
byte[] buffer = new byte[1024];
while (!inflater.finished()) {
int count = inflater.inflate(buffer);
outputStream.write(buffer, 0, count);
}
outputStream.close();
byte[] output = outputStream.toByteArray();
return output;
}
If you have only one file in the zip, you could use the following code. If there are multiple files, just modify the if into a while.
public static byte[] toUnzippedByteArray(byte[] zippedBytes) throws IOException {
var zipInputStream = new ZipInputStream(new ByteArrayInputStream(zippedBytes));
var buff = new byte[1024];
if (zipInputStream.getNextEntry() != null) {
var outputStream = new ByteArrayOutputStream();
int l;
while ((l = zipInputStream.read(buff)) > 0) {
outputStream.write(buff, 0, l);
}
return outputStream.toByteArray();
}
return new byte[0];
}
In java, how to read a fixed length from the inputstream and save as a file?
eg. I want to read 5M from inputStream, and save as downloadFile.txt or whatever.(BUFFERSIZE=1024)
FileOutputStream fos = new FileOutputStream(downloadFile);
byte buffer [] = new byte[BUFFERSIZE];
int temp = 0;
while ((temp = inputStream.read(buffer)) != -1)
{
fos.write(buffer, 0, temp);
}
Two options:
Just keep reading and writing until you either reach the end of the input or you've copied enough:
byte[] buffer = new byte[1024];
int bytesLeft = 5 * 1024 * 1024; // Or whatever
FileInputStream fis = new FileInputStream(input);
try {
FileOutputStream fos = new FileOutputStream(output);
try {
while (bytesLeft > 0) {
int read = fis.read(buffer, 0, Math.min(bytesLeft, buffer.length);
if (read == -1) {
throw new EOFException("Unexpected end of data");
}
fos.write(buffer, 0, read);
bytesLeft -= read;
}
} finally {
fos.close(); // Or use Guava's Closeables.closeQuietly,
// or try-with-resources in Java 7
}
} finally {
fis.close();
}
Read all 5M into memory in one call, e.g. using DataInputStream.readFully, and then write it out in one go. Simpler, but obviously uses more memory.