Efficient way to write InputStream to a File in Java 6

Question

I will get input stream from third party library to my application. I have to write this input stream to a file.

Following is the code snippet I tried:

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Answer 1

It can get cleaner with an OutputStreamWriter:

OutputStream outputStream = new FileOutputStream("output.txt");
Writer writer = new OutputStreamWriter(outputStream);

writer.write("data");

writer.close();

Instead of writing a string, you can use a Scanner on your inputStream

Scanner sc = new Scanner(inputStream);
while (sc.HasNext())
    //read using scanner methods

Answer 2

Since you are stuck with Java 6, do yourself a favour and use Guava and its Closer:

final Closer closer = Closer.create();
final InputStream in;
final OutputStream out;
final byte[] buf = new byte[32768]; // 32k
int bytesRead;

try {
    in = closer.register(createInputStreamHere());
    out = closer.register(new FileOutputStream(...));
    while ((bytesRead = in.read(buf)) != -1)
        out.write(buf, 0, bytesRead);
    out.flush();
} finally {
    closer.close();
}

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Had you used Java 7, the solution would have been as simple as:

final Path destination = Paths.get("pathToYourFile");
try (
    final InputStream in = createInputStreamHere();
) {
    Files.copy(in, destination);
}

And yourInputStream would have been automatically closed for you as a "bonus"; Files would have handled destination all by itself.

Answer 3

If you're not on Java 7 and can't use fge's solution, you may want to wrap your OutputStream in a BufferedOutputStream

BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream("xx.txt"));

Such buffered output stream will write bytes in blocks to the file, which is more efficient than writing byte per byte.