I'm writing an app that takes a 5 second video (.mp4 file) and uploads it to a server as a base64 String. The user can download the video, at which point the String should be converted back to a File.
I'm running into a problem where the downloaded File is saved, but it is slightly smaller (2 to 3 KB smaller) than the original File and is unplayable. This issue does not happen every time that a video is taken; I have been trying to find a pattern for this behavior, but haven't found one yet.
videoFile is a File created through a MediaRecorder recording. I can play back this original File without issue.
Encoding snippet:
//videoFile path: Environment.getExternalStorageDirectory() + "/Pictures/" + timestamp + ".mp4"
byte[] bytes = FileUtils.readFileToByteArray(videoFile);
String encodedVideo = Base64.encodeToString(bytes, Base64.URL_SAFE);
Decoding snippet:
File download = new File(Environment.getExternalStorageDirectory() +"/Pictures/test_"+videoFile.getName());
byte[] decode = Base64.decode(encodedVideo, Base64.URL_SAFE);
FileUtils.writeByteArrayToFile(download, decode);
Log.i("compare arrays",""+(Arrays.toString(bytes)).compareTo(Arrays.toString(decoded)));
The downloaded File is being stored in the same directory as the original File.
Edit to clarify:
The "compare arrays" Log statement gives a result of 0, so the arrays bytes and decode should have the same contents.
I added additional log statements:
Log.i("compare contents", ""+FileUtils.contentEquals(videoFile,download));
Log.i("original checksum", ""+FileUtils.checksumCRC32(videoFile));
Log.i("download checksum", ""+FileUtils.checksumCRC32(download));
to compare the contents of the files more directly.
The log statement comparing the arrays always returns 0, but the contentEquals log statement is not always true. When it is false, the checksums of the files are different. Since the byte arrays have the same contents, I believed the checksums and the actual file contents would be the same as well. This is clearly incorrect, but I don't know how to resolve this issue. Again, I have not found a discernible pattern for when the downloaded File is incorrect.
Any help is appreciated. Where am I going wrong?
Related
i'm trying to delete the first 3 rows of a tif file content generated by a scanner, because i cant open correctly.
example of rows to delete:
------=_Part_23XX49_-1XXXX3073.1XXXXX20715
ID: documento<br>
MimeType: image/tiff
I have no problem about change the content, but when i save the new file, i cant open correctly again.
System.out.println(new InputStreamReader(in).getEncoding());
this method tell me that the encoding of source file is "Cp1252", so i've put an argument in the JVM (-Dfile.encoding=Cp1252), but nothing appear to change.
This is what i do:
StringBuilder fileContent = new StringBuilder();
// working with content and save result content in fileContent variable
// save the file again
FileWriter fstreamWrite = new FileWriter(f.getAbsolutePath());
out = new BufferedWriter(fstreamWrite);
out.write(fileContent.toString());
Is possible that something is going wrong with Encoding?
if i do the operation with notepad++, i obtain a correct tiff that i can open without problem.
I found the TIFF Java library that maybe gonna be useful for your requirements.
Please take a look at the readme how to read and how to write a tiff file.
Hope this can help you
I am attempting to transfer a gzipped file using IOUtils.copyLarge. When I transfer from a GZIPInputStream to a non-compressed output, it works fine, but when I transfer the original InputStream (attempting to leave it compressed) the end result is 0 bytes.
I have verified the input file is correct. Here is an example of what works
IOUtils.copyLarge(new GZIPInputStream(inputStream), out)
This of course results in an uncompressed file being written out. I would like to keep the file compressed as it is in the original input.
When I try val countBytes = IOUtils.copyLarge(inputStream, out) the result is 0, and the resulting file is empty. The desired result is simply copying the already compressed gzip file to a new destination maintaining compression.
Reading the documentation for the API, I should be using this correctly. Any ideas on what is preventing it from working?
I'm a java newbie with a real hair puller. Hope someone can help.
I have a binary file that loads ok from the applet's directory,
but which only partially loads from the applet's jar file.
The code below loads the file both ways and compares them. They
should be identical, but the output is "divergence at byte 8181".
int spx_data_length = 158994;
byte[] spx_buf = new byte[spx_data_length];
byte[] spx_buf2 = new byte[spx_data_length];
// binary file in jar
InputStream is = Vocals.class.getResourceAsStream("0.raw");
is.read(spx_buf, 0, spx_data_length);
is.close();
// same binary file in applet directory
URL srcURL=new URL(getCodeBase(),"0.raw");
URLDataSource u_dat = new URLDataSource(srcURL);
is=u_dat.getInputStream();
is.read(spx_buf2, 0, spx_data_length);
is.close();
// compare them
for(int i=0;ispx_data_length;i++){
if(spx_buf[i] != spx_buf2[i]){
Obj[0]="divergence at byte "+i; win.call("show_string", Obj);
i=spx_data_length;
}
}
InputStream.read(byte[], int, int) will read up to spx_data_length bytes, but may very well read less. Particularly in the case of compressed data (i.e. reading from the JAR), it might return one decompression buffer worth of data at a time. You should either loop until the read returns -1, or use something like DataInputStream.readFully(byte[], int, int). And you should compare the number of bytes read: if that differes, there is little point in comparing the bytes past the smaller of these counts.
I'm working with Java's encryption library and getting a IllegalBlockSizeException.
I am currently trying to extract database contents in XML file format. During the data dump, I am creating a manifest file with a string that gets decrypted using a key defined in the database.
Later, when the contents of the XML's files are loaded into another database, it gets the key from that database and uses it to decrypt the manifest. If the decrypted manifest does not match the original contents, that means the encryption keys in the source and destination databases do not match and the user is notified of this.
The following is the code. The EncryptionEngine object is a singleton that uses the Java encryption library to abstract away a lot of the details of encryption. Assume that it works correctly, as it's fairly old and mature code.
This is all in a class I've made. First, we have these data members:
private final String encryptedManifestContents;
private final static String DECRYPTED_MANIFEST_CONTENTS = "This file contains the encrypted string for validating data in the dump and load process";
final static String ENCRYPTED_MANIFEST_FILENAME = "manifest.bin";
First the encryption process. The string is encrypted like the following:
final EncryptionEngine encryptionEngine = EncryptionEngine.getInstance();
encryptedManifestContents = encryptionEngine.symmetricEncrypt(DECRYPTED_MANIFEST_CONTENTS); // The contents get converted to bytes via getBytes("UTF-8")
Then written to the manifest file (destination is just a variable holding the file path as a string):
EncryptedManifestUtil encryptedManifestUtil = new EncryptedManifestUtil(); // The class I've created. The constructor is the code above, which just initialized the EncryptionEngine and encrypted the manifest string.
manifestOut = new FileOutputStream(destination + "/" + ENCRYPTED_MANIFEST_FILENAME);
manifestOut.write(encryptedManifestUtil.encryptedManifestContents.getBytes("UTF-8"));
At this point, the encryption process is done. We've taken a String, encrypted it, and written the contents to a file, in that order. Now when someone loads the data, the decryption process starts:
BufferedReader fileReader = new BufferedReader(new FileReader(filename)); // Filename is the manifest's file name and location
final EncryptionEngine encryptionEngine = EncryptionEngine.getInstance();
String decryptedManifest = encryptionEngine.decryptString(fileReader.readLine().getBytes("UTF-8")); // This is a symmetric decrypt
When the decryption happens, it throws this exception:
Caused by: javax.crypto.IllegalBlockSizeException: last block incomplete in decryption
at org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(Unknown Source)
at javax.crypto.Cipher.doFinal(DashoA13*..)
It appears to read and write correctly to the file, but the contents are gibberish to me. The result from the fileReader.readLine() is:
9�Y�������䖷�߾��=Ă��� s7Cx�t�b��_-(�b��LFA���}�6�f����Ps�n�����ʢ�#�� �%��%�5P�p
Thanks for the help.
EDIT: So I changed the way I write to a file.
Recall this line:
encryptedManifestContents = encryptionEngine.symmetricEncrypt(DECRYPTED_MANIFEST_CONTENTS);
The encrypt first gets the bytes from the inputted string, then decrypts, then changes the bytes back to a string by first encoding it to the base 64 bytes. Then it converts the base 64 bytes array back to a string.
With this in mind, I changed the file writer to a PrintWriter instead of a FileOutputStream and directly write the string to the file instead of the bytes. I'm still getting the error unfortunately. However there seem to be less of the � in the resulting String from the read line.
It looks like the problem is with your fileReader.readLine() - you're writing a byte stream to a file, and then reading it back in as a string. Instead, you should either read in a byte stream, e.g. refer to this question, or else use Base64 Encoding to convert your byte array to a string, write it to a file, read it from a file, and convert it back to a byte array.
I believe you are incorrectly using a Reader which is an object defined to read characters when you actually want to be dealing strictly in bytes. This is most likely not the entirety of your problem but if you are writing bytes you should read bytes not characters.
I have connected to an ftp location using;
URL url = new URL("ftp://user:password#mydomain.com/" + file_name +";type=i");
I read the content into a byte array as shown below;
byte[] buffer = new byte[1024];
int count = 0;
while((count = fis.read(buffer)) > 0)
{
//check if bytes in buffer is a file
}
I want to be able to check if the bytes in buffer is a file without explicitly passing a specific file to write to it like;
File xfile= new File("dir1/");
FileOutputStream fos = new FileOutputStream(xfile);
fos.write(bytes);
if(xfile.isFile())
{
}
In an Ideal world something like this;
File xfile = new File(buffer);//Note: you cannot do this in java
if(xfile.isFile())
{
}
isFile() is to check if the bytes read from the ftp is file. I don't want to pass an explicit file name as I do not know the name of the file on the ftp location.
Any solutions available?
What is a file?
A computer file is a block of arbitrary information [...] which is available to a computer program and is usually based on some kind of durable storage. A file is durable in the sense that it remains available for programs to use after the current program has finished.
Your bytes that are stored in the byte array will be a part of a file if you write them on some kind of durable storage.
Sure, we often say that we read a file or write a file, but basically we read bytes from a file and write bytes to a file.
So we can't test a byte array whether it's content is a file or not. Simply because every byte array can be used to create a file (even an empty array).
BTW - the ftp server does not send a file, it (1) reads bytes and (2) a filename and (3) sends the bytes and (4) the filename so that a client can (5) read the bytes and (6) the filename and use both datasets to (7) create a file. The ftp server doesn't have to access a file, it can take bytes and names from a database or create both in memory...
I guess you cannot check if the byte[] array is a file or not. Why dont' you just use already written and tested library like maybe for example: http://commons.apache.org/net/
There is no way to do that easily.
A file is a byte array on a disk and a byte array will be a file if you write it to disk. There is no reliable way of telling what is in the data you just received, without parsing the data and checking if you can find a valid file header in it.
Where is isFile() file means the content fetched from from the ftp stream is a file.
The answer to that is simple. You can't do it because it doesn't make any sense.
What you have read from the stream IS a sequence of bytes stored in memory.
A file is a sequence of bytes stored on a disk (typically).
These are not the same thing. (Or if you want to get all theoretical / philosophical you have to answer the question "when is a sequence of bytes a file, and when is it not a file".
Now a more sensible question to ask might be:
How do I know if the stuff I fetched by FTP is the contents of a file on the FTP server.
(... as distinct from a rendering of a directory or something).
The answer is that you can't be sure if you fetched the file by opening an URLConnection to the FTP server ... like you have done. It is like asking "is '(123) 555-5555' a phone number?". It could be a phone number, or it could just be a sequence of characters that look like a phone number.