I have got to retrieve binary in LONGBLOB field from the db. This field is storing all sorts of file formats such as txt, doc, xdoc, pdf, etc. I basically need to be able to convert the binary format into their actual file formats in order to allow my user to download these files.
Has anyone got any idea how to do this?
As others have said, it would be best have another field to store the format. You can do this by copying the extension (ie, everything after the last "." in the file name). The best way would probably be to get the file's mime type: see this for example.
You can then store the mime type in a field in the database. This will almost always work, whereas the extension of a file can be misleading (or vague).
Adding a field file_format indicating the file format of the file stored in LONGBLOB, then you are able to convert the binary according to the associated file format.
or, reserve the first several bytes for file format, after that is the actual content of file.
I think u should have another field to save the document type and tell which type should be converted. Use I/O InputStream to read/write file.
What I recommend is upload the client files to somewhere, save the path that's link to these file into db. That should be faster.
as others have suggested. create another column(FILETYPE_COL_NAME) in database which will tell you which type of file is stored in BOLB(BLOB_COL_NAME) field and then you extend the below code in try/catch block
String fileType = rs.getString("FILETYPE_COL_NAME");
DataOutputStream dos = new DataOutputStream(new BufferedOutputStream(new FileOutputStream("filepath."+fileType )));
ResultSet rs = statement.executeQuery("Select * from tablename");
BufferedInputStream bis = new BufferedInputStream(rs.getBinaryStream("BLOB_COL_NAME"));
byte[] buffer = new byte[1024];
int byteread = 0;
while((byteread = bis.read(buffer)) != -1){
dos.write(buffer, 0, byteread);
}
dos.flush();
dos.close();
bis.close();
Related
I have a database where a Long datatype has an image stored in it,
I want to retrieve it and write it to an image file,
I tried using getBytes method and write a file using for and it return as corrupt image,
I also tried using getBinarystream and write using fos I wrote it in an image file I get same corrupt error.
Code:
InputStream is = RS.getBinaryStream(1);
FileOutputStream fos = new FileOutputStream ("image.bmp");
Int c;
While((c=is.read())!=-1)
{
fos.write(c);
}
fos.close;
To store binary data you should use LONG_RAW or a BLOB. The type LONG is for character based (text) data.
I'm getting from the client an inputStream and file Metadata, and saving it in my SQL table. This table also holds full file path and some unique uid.
I want to be able to pass a uid and get a "handler" to the file, but can't seem to understand if I need to return outputStream, InputStream or File?
Which one should be returned?
I want this handler for the client for the following reasons:
The user will pass it to another function
The user will decide to convert stream to a file and copy it to some local path
Also, When returning outputstram,is it enough to do the following:
OutputStream out = new FileOutputStream(PATH_TO_MY_FILE))
return out;
Am I returning an empty stream? Does out contain all file data?
I thought maybe the best way will be to return file:
File f = new File(PATH_TO_MY_FILE);
return f;
Editing:
My metadata holds file name and file type. When I get InputStream I save in in my folder and set the path in the SQL table to be : folerPath+"/"+filename + "."+ fileType
When The user will run the following function : get(fileUid) I want to retrieve the full path (by using sql query) and return the file (hanlder)
Can you please advise?
Thanks
The user will decide to convert stream to a file and copy it to some local path
This tells us that what you need to give them is an InputStream (or Reader), since they'll be reading from it.
Your code will be reading from your database or whatever, presumably via the InputStream you get back from ResultSet#getBinaryStream or similar. You might give that directly to the caller, or you may prefer to have your code in the middle, perhaps working through a memory buffer.
Re your comment below:
I'm saving the file at some DB folder...
Databases don't have folders; file systems have folders. It sounds like the file isn't stored in your database table, just the path to it. If so, use FileInputStream with the path to get an InputStream for it, which you can return to the caller.
I am implementing a Direct Connect client. I am using the NMDC protocol. I can connect to a hub and other connected clients. I am trying to retrieve the file list from each client, I understand that in order to do that one must download the file files.xml.bz2 from the other client. The protocol to download a file is as follows:
-> $ADCGET file <filename> <params>|
<- $ADCSND file <fileName> <params>|
<- (*** binary data is now transfered from client B to client A ***)
I am trying to create a file named files.xml.bz2 using the binary data received. Here's my code:
//filesize is provided through the $ADCSND response from other client
byte[] data = new byte[filesize];
/*
Reading binary data from socket inputstream
*/
int read = 0;
for (int i=0; read<filesize;){
int available = in2.available();
int leftspace = filesize-read;
if (available>0){
in2.read(data, read, available>leftspace? leftspace:available);
++i;
}
read += (available>leftspace? leftspace:available)+1;
}
/*
writing the bytes to an actual file
*/
ByteArrayInputStream f = new ByteArrayInputStream(data);
FileOutputStream file = new FileOutputStream("files.xml.bz2");
file.write(data);
file.close();
The file is created, however, the contents (files.xml) are not readable. Opening it in firefox gives:
XML Parsing Error: not well-formed
Viewing the contents in the terminal only reads binary data. What am i doing wrong?
EDIT
I also tried Decompressing the file using the bz2 libray from Apache Ant.
ByteArrayInputStream f = new ByteArrayInputStream(data);
BZip2CompressorInputStream bzstream = new BZip2CompressorInputStream(f);
FileOutputStream xmlFile = new FileOutputStream("files.xml");
byte[] bytes = new byte[1024];
while((bzstream.read(bytes))!=-1){
xmlFile.write(bytes);
}
xmlFile.close();
bzstream.close();
I get an error, here's the stacktrace:
java.io.IOException: Stream is not in the BZip2 format
at org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream.init(BZip2CompressorInputStream.java:240)
at org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream.<init>(BZip2CompressorInputStream.java:132)
at org.apache.commons.compress.compressors.bzip2.BZip2CompressorInputStream.<init>(BZip2CompressorInputStream.java:109)
at control.Controller$1.run(Controller.java:196)
Usual, typical misuse of available(). All you need to copy a stream in Java is as follows:
while ((count = in.read(buffer)) >= 0)
{
out.write(buffer, 0, count);
}
Use this with any size buffer greater than zero, but preferably several kilobytes. You don't need a new buffer per iteration, and you don't need to know how much data is available to read without blocking, as you have to block, otherwise you're just smoking the CPU. But you do need to know how much data was actually read per iteration, and this is the first place where your code falls down.
The error java.io.IOException: Stream is not in the BZip2 format is generated by the constructor of class BZip2CompressorInputStream. I decided to scan the bytes, looking for the magic number to make sure that the file was bz2 format, it turns out that Java was right -- it wasnt in bz2 format.
Upon examining the source code of Jucy, I saw that the reason for this was a slight error in the command I sent to the other client, in essence, this error was caused a mistake in my protocol implementation. The solution was:
Replace:
$ADCGET file files.xml.bz2 0 -1 ZL1|
With:
$ADCGET file files.xml.bz2 0 -1|
ZL1 specifies compression of the files being sent (Not necessary).
I have a question looks to me so hard at first glance but maybe has very easy solution that I cant figure it out yet. I need to read binary data of an excel file which stored in a oracle database CLOB column.
Everything is ok with reading CLOB as string in java. I get excel file as binaries on a string parameter.
String respXLS = othRaw.getOperationData(); // here I get excel file
InputStream bais = new ByteArrayInputStream(respXLS.getBytes());
POIFSFileSystem fs = new POIFSFileSystem(bais);
HSSFWorkbook wb = new HSSFWorkbook(fs);
Then I try to read ByteStreamData and put in POIFSFileSystem but I get this exception:
java.io.IOException: Invalid header signature; read 0x00003F1A3F113F3F, expected 0xE11AB1A1E011CFD0
I googled some excel problems, they mention about read access. So I download same excel file to hdd and change nothing with it(even I did not open it), and use FileInputStream by giving the file path. It has worked flawless. So what is the reason?
Any advice or alternative way to read from CLOB will be appreciated.
Thanks in advance,
My Regards.
CLOB means Character Large OBject; You want to use a BLOB - Binary Large OBject. Change your database schema.
What happens is that a CLOB will use a Character Set to convert your String to/from the database internal format, whatever that is; this will cause file corruption on non-text contents.
Repeat after me: a String is not a byte[], and a character is not a byte.
I'm retrieving a file from a FTP Server. The file is encoded as UTF-8
ftpClient.connect(props.getFtpHost(), props.getFtpPort());
ftpClient.login(props.getUsername(), props.getPassword());
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
inputStream = ftpClient.retrieveFileStream(fileNameBuilder
.toString());
And then somewhere else I'm reading the input stream
bufferedReader = new BufferedReader(new InputStreamReader(
inputStream, "UTF-8"));
But the file is not getting read as UTF-8 Encoded!
I tried ftpClient.setAutodetectUTF8(true); but still doesn't work.
Any ideas?
EDIT:
For example a row in the original file is
...00248090041KENAN SARÐIN 00000000015.993FAC...
After downloading it through FTPClient, I parse it and load in a java object, one of the fields of the java object is name, which for this row is read as "KENAN SAR�IN"
I tried dumping to disk directly:
File file = new File("D:/testencoding/downloaded-file.txt");
FileOutputStream fop = new FileOutputStream(file);
ftpClient.retrieveFile(fileName, fop);
if (!file.exists()) {
file.createNewFile();
}
I compared the MD5 Checksums of the two files(FTP Server one and the and the one dumped to disk), and they're the same.
I would separate out the problems first: dump the file to disk, and compare it with the original. If it's the same as the original, the problem has nothing to do with UTF-8. The FTP code looks okay though, and if you're saying you want the raw binary data, I'd expect it not to mess with anything.
If the file is the same after transfer as before, then the problem has nothing to do with FTP. You say "the file is not getting read as UTF-8 Encoded" but it's not clear what you mean. How certain are you that it's UTF-8 text to start with? If you could edit your question with the binary data, how it's being read as text, and how you'd expect it to be read as text, that would really help.
Try to download the file content as bytes and not as characters using InputStream and OutputStream instead of InputStreamReader. This way you are sure that the file is not changed during transfer.