I would like to use bufferedInputStream and bufferedOutputStream to copy large binary files from source file to destination file.
Here is my code:
byte[] buffer = new byte[1000];
try {
FileInputStream fis = new FileInputStream(args[0]);
BufferedInputStream bis = new BufferedInputStream(fis);
FileOutputStream fos = new FileOutputStream(args[1]);
BufferedOutputStream bos = new BufferedOutputStream(fos);
int numBytes;
while ((numBytes = bis.read(buffer))!= -1)
{
bos.write(buffer);
}
//bos.flush();
//bos.write("\u001a");
System.out.println(args[0]+ " is successfully copied to "+args[1]);
bis.close();
bos.close();
} catch (IOException e)
{
e.printStackTrace();
}
I can successfully copy but then I use
cmp src dest
in the command line to compare two files.
The error message
cmp: EOF on files
appears. May I know where I was wrong?
This is the mistake:
bos.write(buffer);
You're writing out the whole buffer, even if you only read data into part of it. You should use:
bos.write(buffer, 0, numBytes);
I'd also suggest using try-with-resources if you're using Java 7 or later, or put the close calls in a finally block otherwise.
As Steffen notes, Files.copy is a simpler approach if that's available to you.
If you are using Java 8 try the Files.copy(Path source, Path target) method.
you need to close your FileOutputStream and FileInputStream
Also you can use FileChannel to copy like as follows
FileChannel from = new FileInputStream(sourceFile).getChannel();
FileChanngel to = new FileOutputStream(destFile).getChannel();
to.transferFrom(from, 0, from.size());
from.close();
to.close();
You could use IOUtils from apatch-commons library
I think copyLarge fucntion it that you need
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 trying to port the following java code to .net:
private final byte[] zipLicense(byte lic[])
{
byte buf[];
ByteArrayInputStream bis;
DeflaterInputStream dis;
ByteArrayOutputStream bos;
buf = new byte[64];
bis = new ByteArrayInputStream(lic);
dis = new DeflaterInputStream(bis, new Deflater());
bos = new ByteArrayOutputStream();
byte abyte0[];
int len;
while((len = dis.read(buf)) > 0)
bos.write(buf, 0, len);
abyte0 = bos.toByteArray();
try
{
bis.close();
dis.close();
bos.close();
}
catch(IOException ex)
{
ex.printStackTrace();
}
return abyte0;
}
My best shot was this code in C#:
private byte[] zipLicense(byte[] lic)
{
var outputMemStream = new MemoryStream();
ZipOutputStream zipStream;
using (zipStream = new ZipOutputStream(outputMemStream))
{
zipStream.Write(lic, 0, lic.Length);
Debug.WriteLine(string.Format("Compressed bytes: {0}", outputMemStream.Length));
}
return outputMemStream.ToArray();
}
ZipOutputStream is a class from SharpZipLib
When I try to run the C# code, I get error on first attempt to write to zipStream
zipStream.Write(lic, 0, lic.Length);
The error states that I haven't provided "No entry". I see in examples that one can and probably should seciffy an entry string to a zip stream, but what java code puts as an entry then? Please help in porting this java functionality to .Net. Thanks!
The Java DeflaterInputStream is more like .NET's DeflateStream. That is, it's simply a compressed stream, without the directory index that a full .zip file would contain.
Try this:
private byte[] zipLicense(byte[] lic)
{
var outputMemStream = new MemoryStream();
using (DeflateStream stream =
new DeflateStream(outputMemStream, CompressionMode.Compress, true))
{
stream.Write(lic, 0, lic.Length);
}
Debug.WriteLine(string.Format("Compressed bytes: {0}", outputMemStream.Length));
return outputMemStream.ToArray();
}
Note that I've added a call to Flush(). Without this, the outputMemStream.Length property may not be current (i.e. not quite the full length of the resulting stream).
For what it's worth, .NET now has reasonably good .zip file support built-in (e.g. ZipArchive class). So if you do find yourself actually needing that some day, I would try to use that first rather than adding a third-party library to your deployment.
I am trying to unzip a response from a .net middleware. The response has been ziped using GZipStream.
GZipStream zipStream = new GZipStream(fileStream, CompressionMode.Compress, true);
when I used GZIPInputStream in java to unzip the file. I am getting an IOException with message "not in zip format" in the following code.
GZIPInputStream gzin = new GZIPInputStream(response);
I tried this too.
ByteArrayInputStream memstream = new ByteArrayInputStream(buffer2);
GZIPInputStream gzin = new GZIPInputStream(memstream);
Any help or suggestions are welcomed.
Thanks in advance
Try something like this
GZIPInputStream gis = null;
FileOutputStream fos = null;
try {
gis = new GZIPInputStream(new FileInputStream("pathOfTheGZipFile"));
fos = new FileOutputStream("pathOfDecompressedFile");
byte[] buffer = new byte[gis.available()];
int len;
while((len = gis.read(buffer)) != -1){
fos.write(buffer, 0, len);
}
} catch (IOException e) {
e.printStackTrace();
}
finally {
fos.close();
gis.close();
}
I have finally figured out the solution, In the response returned by the server first few bytes were not zipped so if any one is facing the same issue you just need to check the bytes. After I removed those bytes from response. It started working.
I`m hoping can help me out with a file creation/response question.
I know how to create and save a file. I know how to send that file back to the user via a ServletOutputStream.
But what I need is to create a file, without saving it on the disk, and then send that file via the ServletOutputStream.
The code above explains the parts that I have. Any help appreciated. Thanks in Advance.
// This Creates a file
//
String text = "These days run away like horses over the hill";
File file = new File("MyFile.txt");
Writer writer = new BufferedWriter(new FileWriter(file));
writer.write(text);
writer.close();
// Missing link goes here
//
// This sends file to browser
//
InputStream inputStream = null;
inputStream = new FileInputStream("C:\\MyFile.txt");
byte[] buffer = new byte[8192];
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int bytesRead;
while ( (bytesRead = inputStream.read(buffer)) != -1)
baos.write(buffer, 0, bytesRead);
response.setContentType("text/html");
response.addHeader("Content-Disposition", "attachment; filename=Invoice.txt");
byte[] outBuf = baos.toByteArray();
stream = response.getOutputStream();
stream.write(outBuf);
You don't need to save off a file, just use a ByteArray stream, try something like this:
inputStream = new ByteArrayInputStream(text.getBytes());
Or, even simpler, just do:
stream.write(text.getBytes());
As cHao suggests, use text.getBytes("UTF-8") or something similar to specify a charset other than the system default. The list of available charsets is available in the API docs for Charset.
I have a simple question. I'm trying to upload a file to my ftp server in Java.
I have a file on my computer, and I want to make a copy of that file and upload it. I tried manually writing each byte of the file to the output stream, but that doesn't work for complicated files, like zip files or pdf files.
File file = some file on my computer;
String name = file.getName();
URL url = new URL("ftp://user:password#domain.com/" + name +";type=i");
URLConnection urlc = url.openConnection();
OutputStream os = urlc.getOutputStream();
//then what do I do?
Just for kicks, here is what I tried to do:
OutputStream os = urlc.getOutputStream();
BufferedReader br = new BufferedReader(new FileReader(file));
String line = br.readLine();
while(line != null && (!line.equals(""))) {
os.write(line.getBytes());
os.write("\n".getBytes());
line = br.readLine();
}
os.close();
For example, when I do this with a pdf and then try and open the pdf that I run with this program, it says an error occurred when trying to open the pdf. I'm guessing because I am writing a "\n" to the file? How do I copy the file without doing this?
Do not use any of the Reader or Writer classes when you're trying to copy the byte-for-byte exact contents of a binary file. Use these only for plain text! Instead, use the InputStream and OutputStream classes; they do not interpret the data at all, while the Reader and Writer classes interpret the data as characters. For example
OutputStream os = urlc.getOutputStream();
FileInputStreamReader fis = new FileInputStream(file);
byte[] buffer = new byte[1000];
int count = 0;
while((count = fis.read(buffer)) > 0) {
os.write(buffer, 0, count);
}
Whether your URLConnection usage is correct here, I don't know; using Apache Commons FTP (as suggested elsewhere) would be an excellent idea. Regardless, this would be the way to read the file.
Use a BufferedInputStream to read and BufferedOutputStream to write. Take a look at this post: http://www.ajaxapp.com/2009/02/21/a-simple-java-ftp-connection-file-download-and-upload/
InputStream is = new FileInputStream(localfilename);
BufferedInputStream bis = new BufferedInputStream(is);
OutputStream os =m_client.getOutputStream();
BufferedOutputStream bos = new BufferedOutputStream(os);
byte[] buffer = new byte[1024];
int readCount;
while( (readCount = bis.read(buffer)) > 0) {
bos.write(buffer, 0, readCount);
}
bos.close();
FTP usually opens another connection for data transfer.
So I am not convinced that this approach with URLConnection is going
to work.
I highly recommend that you use specialized ftp client. Apache commons
may have one.
Check this out
http://commons.apache.org/net/api/org/apache/commons/net/ftp/FTPClient.html