I'm downloading an attachment using Java mail API and whenever there is a small change in network state, my app gets stuck and I have to restart it, it's not even crashing.
This is the code snippet:
InputStream is = bodyPart.getInputStream();
String fileName = MimeUtility.decodeText(bodyPart.getFileName());
// Downloading the file
File f = new File(Constants.getPath() + fileName);
try {
FileOutputStream fos;
fos = new FileOutputStream(f);
byte[] buf = new byte[8*1024];
int bytesRead;
while ((bytesRead = is.read(buf)) != -1) {
fos.write(buf, 0, bytesRead);
}
fos.close();
}
What is the best way to deal with this issue? Thanks.
Your application is stuck. The solution to that is to set a read timeout, as discussed in this question. If the timeout occurs a SocketTimeoutException will be thrown.
Related
I have a simple program which gets BufferedInputStream from URL and I have seen that while reading from the underlying stream, read(bytes) calls goes to FileInputStream from BufferedInputStream (so for this I convinced my self saying as at the other end of socket , it is actually a file may be that's why it goes to FileInputStreams (Please let me know if my assumptions are correct about this )).
When read happens in FileInputStreams read() method the "path" variable is set to the location of my class file from where the read call is being invoked , well this is very confusing to me as I was expecting the file's actual URL location here which I am downloading ..
Please help me understand these things and how actually read() happens from a remote file ??
URL url = new URL("some url for downloading a file");
BufferedInputStream bis = new BufferedInputStream(url.openStream());
FileOutputStream fis = new FileOutputStream(file);
int size = 65536;
byte[] buffer = new byte[size];
int count;
while ((count = bis.read(buffer, 0, size)) != -1) {
fis.write(buffer, 0, count);
}
fis.close();
bis.close();
I am working on transferring a file between two computers over a socket. Everything seems to work, but when I look at the contents of the retrieved file, it is empty. What am I doing wrong?
Here is my server-side code. The file foobar.txt exists, and its contents are "hello world!".
try{
ServerSocket ssock = new ServerSocket(12345);
Socket sock = ssock.accept();
//here I get the filename from the client, but that works fine.
File myFile = new File("foobar.txt");
byte[] mybytearray = new byte[(int) myFile.length()];
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(myFile));
bis.read(mybytearray, 0, mybytearray.length);
OutputStream os = sock.getOutputStream();
os.write(mybytearray, 0, mybytearray.length);
os.flush();
sock.close();
} catch (Exception e){
e.printStackTrace();
}
And here is my client code:
try {
Socket socket = new Socket(host, port);
PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
out.print("get foobar.txt\r\n");
out.flush();
byte[] streamIn = new byte[1024];
InputStream in = socket.getInputStream();
FileOutputStream file_src = new FileOutputStream("foobar.txt");
BufferedOutputStream file_writer = new BufferedOutputStream(file_src);
int i;
while ((i = in.read()) != -1) {
file_writer.write(i);
}
file_writer.flush();
file_writer.close();
file_src.close();
socket.close();
} catch (Exception e) {
e.printStackTrace();
}
Solved
Since I am using multiple threads and multiple sockets and testing all connections on one machine, I was simply running into a problem where the client (which has both the client and server code in it) would connect with itself instead of the other client. Changing the file transfer port for the different running clients got this all to work. Thanks for everyone who had a look at this and gave me some suggestions.
Maybe you're closing the wrong socket on the client. When you close the socket, you're closing the class field this.socket instead of the local variable socket.
Also, when you close the output stream to the file, you don't have to close both the BufferedOutputStream and the FileOutputStream. The FileOutputStream is automatically closed when the BufferedOutputStream is closed.
One more thing---you don't have to flush an output stream before closing it. When you call close() the stream is automatically flushed.
In addition to what everyone else has said, you are ignoring the result of bis.read(). It isn't guaranteed to fill the buffer. See the Javadoc.
The correct way to copy streams in Java, which you should use at both ends, is this:
byte[] buffer = new byte[8192]; // or whatever
int count;
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
The only thing I think of that is that you actually never start receiving the file because the server-side doesn't read the command ("get foobar.txt"), so the client-side freezes on sending the command.
The existence of the file at the client-side might be from previous tests.
But, I'm not sure this is the problem. It's just a try to help.
My application is unable to transfer data properly over a socket connection and write it to a file properly. Files over about 65,535 bytes get corrupted and are no longer recognized by the programs designed to run them.
I have been able to send small .doc and .txt files successfully, but .mp3 .wmv .m4a .avi and just about anything else does not work. Neither do larger docs.
I have looked all over the internet for a solution to this problem. I have repeatedly tweaked the I/O code to fix the problem but it still doesn't work! Here is the I/O code in the super class that handles sending and receiving files. If you need anymore information/other parts of code, let me know.
protected void sendFile() throws IOException {
byte[] bytes = new byte[(int) file.length()];
buffin = new BufferedInputStream(new FileInputStream(file));
int bytesRead = buffin.read(bytes,0,bytes.length);
System.out.println(bytesRead);
out = sock.getOutputStream();
out.write(bytes,0,fileBytes);
out.flush();
out.close();
}
protected void receiveFile() throws IOException {
byte[] bytes = new byte[fileBytes];
in = sock.getInputStream();
for(int i=0;i<fileBytes;i++) {
in.read(bytes);
}
fos = new FileOutputStream("/Datawire/"+fileName);
buffout = new BufferedOutputStream(fos);
buffout.write(bytes,0,fileBytes);
buffout.flush();
buffout.close();
}
UPDATED CODE (that works):
protected void sendFile() throws IOException {
if((file.length())<63000) {
byte[] bytes = new byte[(int)file.length()];
buffin = new BufferedInputStream(new FileInputStream(file));
buffin.read(bytes,0,bytes.length);
out = sock.getOutputStream();
out.write(bytes,0,bytes.length);
out.close();
} else {
byte[] bytes = new byte[32000];
buffin = new BufferedInputStream(new FileInputStream(file));
out = sock.getOutputStream();
int bytesRead;
while((bytesRead = buffin.read(bytes))>0) {
out.write(bytes,0,bytesRead);
}
out.close();
}
}
protected void receiveFile() throws IOException {
if(fileBytes<63000) {
byte[] bytes = new byte[32000];
in = sock.getInputStream();
System.out.println(in.available());
in.read(bytes,0,fileBytes);
fos = new FileOutputStream("/Datawire/"+fileName);
buffout = new BufferedOutputStream(fos);
buffout.write(bytes,0,bytes.length);
buffout.close();
} else {
byte[] bytes = new byte[16000];
in = sock.getInputStream();
fos = new FileOutputStream("/Datawire/"+fileName);
buffout = new BufferedOutputStream(fos);
int bytesRead;
while((bytesRead = in.read(bytes))>0) {
buffout.write(bytes,0,bytesRead);
}
buffout.close();
}
}
The issue is that you are sending only chunks of it. That is, you are only sending 64k of the file ever. If the file is ever larger then 64k the other end will never see it.
You want to continously read from the BufferedInputStream until the read() returns either less then the length or -1.
Your code is completely wrong. This is how to copy a stream in Java:
int count;
byte[] buffer = new byte[8192]; // more if you like but no need for it to be the entire file size
while ((count = in.read(buffer)) > 0)
{
out.write(buffer, 0, count);
}
You should use this both when sending the file and when receiving the file. At present your sending method hopes that the entire file fits into memory; fits into INTEGER_MAX bytes; and is read in one chunk by the read method, without even checking the result. You can't assume any of those things. Your receive method is complete rubbish: it just keeps overwriting the same array, again without checking any read() results.
EDIT: Your revised code is just as bad, or worse. You are calling read() to check for EOS and then throwing that byte away, and then calling read() again and throwing away the read count it returns. You pointlessly have a different path for files < 64000, or 63000, or whatever it is, that has zero benefit except to give you two code paths to test, or possibly four, instead of one. The network only gives you 1460 bytes at a time at best anyway so what is the point? You already have (a) a BufferedInputStream with a default buffersize of 8192, and (b) my code that uses a byte[] buffer of any size you like. My code above works for any amount of data in two lines of executable code. Yours is 20. QED.
I suggest that you use some good library to read and write file contents as well as socket read/write. For example Apache Commons IO. If you insist on writig code yourself, do it smaller chunks rather than the whole file at once.
You have to consider that InputStream.read returns the number of bytes read which may be less than the total number of bytes in the file.
You would probably be better off just letting something like CopyUtils.copy take care of this for you.
You need to loop until bytesRead < 0. You need to make sure that fileBytes is => than the transferred file.
protected void receiveFile() throws IOException {
byte [] bytes = new byte [fileBytes];
InputStream is = sock.getInputStream();
FileOutputStream fos = new FileOutputStream("/Datawire/"+fileName);
BufferedOutputStream bos = new BufferedOutputStream(fos);
int bytesRead = is.read(bytes,0,bytes.length);
int current = bytesRead;
do {
bytesRead =
is.read(bytes, current, (bytes.length-current));
if(bytesRead >= 0) current += bytesRead;
} while(bytesRead > -1);
bos.write(bytes, 0 , current);
bos.flush();
bos.close();
}
I am sending a file to the browser in a servlet. The highest JDK I can use is 1.4.2, and I also have to retrieve the file via a URL. I am also trying to use "guessContentTypeFromStream", but I keep getting null which raises an exception when used in the code sample below. I currently have to hard code or work out the content-type myself.
What I would like to know is, how I can re-factor this code so the file transmission is as fast as possible and also use guessContentTypeFromStream ? (Note "res" is HttpServletResponse).
URL servletUrl = new URL(sFileURL);
URLConnection conn = servletUrl.openConnection();
int read;
BufferedInputStream bis = new BufferedInputStream(conn.getInputStream());
String sContentType =conn.guessContentTypeFromStream(conn.getInputStream());
res.setContentType(sContentType);
//res.setContentType("image/jpeg");
PrintWriter os = res.getWriter();
while((read = bis.read()) != -1){
os.write(read);
}
//Clean resources
os.flush();
This is how you normally read/writes data.
in = new BufferedInputStream(socket.getInputStream(), BUFFER_SIZE);
byte[] dataBuffer = new byte[1024 * 16];
int size = 0;
while ((size = in.read(dataBuffer)) != -1) {
out.write(dataBuffer, 0, size);
}
I call a service which returns a gzipped file. I have the data as an InputStream (courtesy of javax.activation.DataHandler.getInputStream();) from the response.
What I would like to do is, without writing anything to disk, get an InputStream of the decompressed data in the file that is in the archive. The compressed file in this case is an xml document that I am trying to unmarshal using javax.xml.bind.Unmarshaller which takes an InputStream.
I'm currently trying to write the InputStream to an OutputStream (decompressing the data) and then I'll need to write it back to an InputStream. It's not working yet so I thought I would see if there was a better (I would hope so) approach.
I can write the initial InputStream to disk and get a gz file, and then read that file, get the compressed file out of it and go from there but I'd rather keep it all in memory is possible.
Update 1: Here is my current (not working - get a "Not in GZIP format" exception):
ByteArrayInputStream xmlInput = null;
try {
InputStream in = dh.getInputStream(); //dh is a javax.activation.DataHandler
BufferedInputStream bis = new BufferedInputStream(in);
ByteArrayOutputStream bo = new ByteArrayOutputStream();
int bytes_read = 0;
byte[] dataBuf = new byte[4096];
while ((bytes_read = bis.read(dataBuf)) != -1) {
bo.write(dataBuf, 0, bytes_read);
}
ByteArrayInputStream bin = new ByteArrayInputStream(bo.toByteArray());
GZIPInputStream gzipInput = new GZIPInputStream(bin);
ByteArrayOutputStream out = new ByteArrayOutputStream();
dataBuf = new byte[4096];;
bytes_read = 0;
while ((bytes_read = gzipInput.read(dataBuf)) > 0) {
out.write(dataBuf, 0, bytes_read);
}
xmlInput = new ByteArrayInputStream(out.toByteArray());
If instead of writing to a ByteArrayOutputStream I write to a FileOutputStream the first time around I get a compressed file (which I can manually open to get the xml file within) and the service (eBay) says it should be a gzip file so I'm not sure why I get a "Not in GZIP format" error.
Update 2: I tried something a little different - same error ("Not in GZIP format"). Wow, I just tried to end that parenthesis with a semi-colon. Anyways, here is my second attempt, which still does not work:
ByteArrayInputStream xmlInput = null;
try {
GZIPInputStream gzipInput = new GZIPInputStream(dh.getInputStream());
ByteArrayOutputStream bo = new ByteArrayOutputStream();
int bytes_read = 0;
byte[] dataBuf = new byte[4096];
while ((bytes_read = gzipInput.read(dataBuf)) != -1) {
bo.write(dataBuf, 0, bytes_read);
}
xmlInput = new ByteArrayInputStream(bo.toByteArray());
Decorate the input stream with a GZIPInputStream.
InputStream decompressed = new GZIPInputStream(compressed);
The following code should work. Keep in mind you'll have to handle exceptions properly.
OutputStream out = null;
InputStream in = null;
try {
out = /* some output stream */;
in = new java.util.GZIPInputStream(/*some stream*/);
byte[] buffer = new byte[4096];
int c = 0;
while (( c = in.read(buffer, 0, 4096)) > 0) {
out.write(buffer, 0, c);
}
} finally {
if (in != null) {
in.close();
}
if (out != null) {
out.close();
}
}
Take a look at GZIPInputStream. Here's an example; the class handles this very transparently, it's almost no work to use.