I want to write two simple utilities:
Receives a Binary file, and converts it to a text file (ASCII format).
Receives a text file in the format of the above file and restores the original binary file.
The reason I need this is that very stupid, but still a reason. I have two computers - one with internet access and one without. I write software on the one without internet. I get emails on the 2nd one. I need to transfer binary files from one to another (e.g. jars) but the only communication between them is a clipboard (text only).
Might be a very localized problem - but I assume it has some solution in the worlds of data encryption/compression/network transfer.
The only thing I could come up is go over the binary file and convert each byte into it's HEX representation - so for every byte I'll get two ASCII characters (i.e. two bytes). Is there anything better? (This solution doubles the amount of info and might not be possible to transfer via clipboard)
One limitation - I need it as a java based solution (I want to write it myself)
Google for Base64, and use Apache commons codec to have a ready to use implementation.
Related
How do I write to a pre-specified binary file format in Java that I can share with another computer that will parse it (and other computer is not using Java)? The file format has longs, floats, and some bitfields. This is a file that the Java program will write data to and then share with another computer. Is there a better way to do this than with a binary file format?
If it doesn't have to be binary you can use XML or JSON. If it has to be binary, use Protocol Buffers.
If it has to be binary, I would use ByteBuffer which support reading/write primitive in any combination and with any byte order (endianess) You can create wrappers so when you read/write it can appear as events, messages or event types (so you hide the fact you are dealing with a binary file)
I am storing large amounts of information inside of text files that are written via java. I have two questions relating to this:
Is there any efficiency boost to writing in binary or bytecode over Strings?
What would I use to write the data type into a file.
I already have a setup based around Strings, but I want to compare and at least know how to write the file in bytecode or binary.
When I read in the file, it will be translated into Strings again, but according to my reasearch if I write the file straight into bytecode it removes the added process on both ends of translating between Strings and code both for writing the file and for reading it.
cHao has a good point about just using Strings anyway, but I am still interested in the how if how to write varied data types in the file.
In other words, can I still use the FileReader and BufferedReader to read and translate back to Strings, or is there another thing to use. Also using a BinaryWriter, is it still just the FileWriter class that I use???
If you want to write it in "binary", and you want to save space, why not just zip it using the jdk? Meets all your requirements.
Are there libraries out there that can convert data (text files, etc) to sound and back to the original data?
The sound can be transmitted any medium I wish, whether radio, etc. I just need to store data in sound files.
Scenario:
step1: Convert a .docx file with embedded images to .wav.
step2: Send over a radio wave.
step3: Convert this .wav back to the .docx file with the embedded images.
This concept can be applied to any data.
Technology:
.net or java
I think the medium is important, as are other factors such as the size of the files and the transmission time available. A simple algorithm would be to convert your files to text (UUENCODE should do that trick) then convert to morse code : http://www.codeproject.com/KB/vb/morsecode.aspx
Morse gives you a simple alphabet able to survive transmission over a fairly noisy radio channel.
If your carrier is cleaner a conversion of your UUEncoded file into a series of frequencies one per character would probably also work, and be easy enough to decode at the other end, Frequency Analyzer in C#
You could try to use the magnetic card technology for your files, I'm also trying to do this on android.
Any data can be converted to byte into a string of characters it very possible with java and android.
then use the Encoding mechanism of Magnetic Cards API to encode the string to sound. Then you can just use the vice versa, convert the sound into string convert string into byte and save the data. It's just it takes time to convert both ways but it is feasible, I'm trying to do this so that any one with unlimited voice connection can transfer files or in the future browse the internet just through calling the other number. I hope I gave you some idea.
The problem is that the data in a word document doesn't necessarily make decent sound. If you pick a 1.8kHz carrier and use the binary contents of the word document to modulate the volume or the frequency (AM or FM) the result will be messy and hardly to decode.
But if you save the document as a bitmap, you can use the pixel values to modulate the volume of the carrier wave.
We've been sending pictures (not just black/white but greyscale and color (three different separations of the image, r, g and b) over phonelines using this method for many years before modems and the internet took off.
The fun part is that you can broadcast data this way. The sound can be received by more than one receiver at the same time. There's no error correction, but as you deal with visual data, you don't have to worry about a few pixels getting lost. It's similar to old fax protocols.
Does the audio file need to be convertible using lossy compressors (MP3 etc.)? If not, you can just add a WAV container around any binary data and you'll be fine. Otherwise it gets more difficult, and you need to ensure that the audio is audible (in a reasonable frequency range when played) and be tolerant enough on the frequency detection to match the output of lossy codecs.
Best way is to convert the audio file into binary and store in a file type you specify.
Try out the AudioInputStream Class in Java
To give what I think is a better response to all of the above, have a look at packet radio and the various bits that correspond to it AX.25 is a good example and there are a number of implementations for it. POCSAG is also another good implementation. Both have libraries available for many different languages and have been around for quite a long time.
Other example include things like WEFAX (weather fax), HFFax, SSTV (slow scan tv), etc.
You can think of them all as being similar to the old school phone line modem type encoders and decoders that run around the 300-2400baud
I've to make a code to upload/download a file on remote machine. But when i upload the file new line is not saved as well as it automatically inserts some binary characters. Also I'm not able to save the file in its actual format, I've to save it as "filename.ser". I'm using serialization-deserialization concept of java.
Thanks in advance.
How exactly are you transmitting the files? If you're using implementations of InputStream and OutputStream, they work on a byte-by-byte level so you should end up with a binary-equal output.
If you're using implementations of Reader and Writer, they convert the bytes to characters according to some character mapping, and then perform the reverse process when saving. Depending on the platform encodings of the various machines (and possibly other effects if you're not specifying the charset explicitly), you could well end up with differences in the binary file.
The fact that you mention newlines makes me think that you're using Readers to send strings (and possibly that you're stitching the strings back together yourself by manually adding newlines). If you want the files to be binary equal, then send them as a stream of bytes and store that stream verbatim. If you want them to be equal as strings in a given character set, then use Readers and Writers but specify the character set explicitly. If you want them to be transmitted as strings in the platform default set (not very useful), then accept that they're not going to be binary equal as files.
(Also, your question really doesn't provide much information to solve it. To me, it basically reads "I wrote some code to do X, and it doesn't work. Where did I go wrong?" You seem to assume that your code is correct by not listing it, but at the same time recognise that it's not...)
Has anybody written any classes for reading and writing Palm Database (PDB) files in Java? (I mean on a server, not on the Palm device itself.) I tried to google, but all I got were Protein Data Bank references.
I wrote a Perl program that does it using Palm::PDB.pm, but I want to turn it into a servlet for a GWT app.
The jSyncManager project at http://www.jsyncmanager.org/ is under the LGPL and includes classes to read and write PDB files -- look in jSyncManager/API/Protocol/Util/DLPDatabase.java in its source code. It looks like the core code you need from this could be isolated from the rest of the library with a little effort.
There are a few ways that you can go about this;
Easiest but slowest: Find a perl-> java bridge. This will not be quick, but it will work and it should involve the least amount of work.
Find a C++/C# implementation that you have the source to and convert it (this should be the fastest solution)
Find a Java reader ... there seems to be a few listed under google... however I do not have any experience with these.
Depending on what your intended usage is, you might look into writing a simple reader yourself. The format is pretty simple and you only need to handle a couple of simple fields to parse it.
Basically there is a header for the entire file which has a 2 byte integer at the end which specifies the number of record. So just skip your way through the bytes for all the other fields in the header and then read the last field which is the number of records in the file. Be aware that the PDB format writes integers with most significant byte first.
Following this, there will be a record header for each record, the first field of which is the actual offset into the file for the record itself. Again, be aware of the byte order.
So, now you have the offsets into the file for each record in the file, which should make it very easy to read the actual records as long as you know the format of these for the type of PDB file you are trying to read.
Wikipedia has a nice overview of the header formats.
Maybe JPilot can help? They must have a lot of Java code dealing with Palm OS data.