将字节数组写入文件的快速方法

Question

On my app I use Files.write and org.jclouds.blobstore.domain.Blob.putBlob to write a byte array into 4MB files. Both in a concurrent way. The second option (jcloud) is faster.

I wounder to know if there is a faster way to write a byte array int a file. If I implement my Files.write it is better.

Thanks

Answer 1

I looked at the code, and (surprisingly) Files.write(Path, byte[], OpenOption ...) writes the file using a fixed sized buffer of 8192 bytes. (Java 7 & Java 8 versions)

You should be able to get better performance by doing the write directly; eg

    byte[] bytes = ...
    try (FileOutputStream fos = new FileOutputStream(...)) {
        fos.write(bytes);
    }

Answer 2

I did two programs. First using Files.write and second Using FileOutputStream to create 1000 files of 4MB. Files.write took 47 sec and FileOutputStream 53 sec.

public class TestFileWrite {

    public static void main(String[] args) {
        try {
            Path path = Paths.get("/home/felipe/teste.txt");
            byte[] data = Files.readAllBytes(path);

            SimpleDateFormat sdf = new SimpleDateFormat("YYYY-MM-DD HH:mm:ss");
            System.out.println("TestFileWrite");
            System.out.println("start: " + sdf.format(new Date()));
            for (int i = 0; i < 1000; i++) {
                Files.write(Paths.get("/home/felipe/Test/testFileWrite/file" + i + ".txt"), data);
            }
            System.out.println("end: " + sdf.format(new Date()));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}



public class TestOutputStream {

    public static void main(String[] args) {
        Path path = Paths.get("/home/felipe/teste.txt");
        byte[] data = null;
        try {
            data = Files.readAllBytes(path);
        } catch (IOException e1) {
            e1.printStackTrace();
        }

        SimpleDateFormat sdf = new SimpleDateFormat("YYYY-MM-DD HH:mm:ss");
        System.out.println("TestOutputStream");
        System.out.println("start: " + sdf.format(new Date()));

        for (int i = 0; i < 1000; i++) {
            try (OutputStream out = new FileOutputStream("/home/felipe/Test/testOutputStream/file" + i + ".txt")) {
                out.write(data);
            } catch (IOException e) {
                e.printStackTrace();
            }
            // Files.write(Paths.get("), data);
        }
        System.out.println("end: " + sdf.format(new Date()));
    }
}