不考虑多线程优化,单线程文件复制最快的方法是(文件越大该方法越有优势,一般比常用方法快30+%):
- private static void nioTransferCopy(File source, File target) {
- FileChannel in = null;
- FileChannel out = null;
- FileInputStream inStream = null;
- FileOutputStream outStream = null;
- try {
- inStream = new FileInputStream(source);
- outStream = new FileOutputStream(target);
- in = inStream.getChannel();
- out = outStream.getChannel();
- in.transferTo(0, in.size(), out);
- } catch (IOException e) {
- e.printStackTrace();
- } finally {
- close(inStream);
- close(in);
- close(outStream);
- close(out);
- }
- }
private static void nioTransferCopy(File source, File target) { FileChannel in = null; FileChannel out = null; FileInputStream inStream = null; FileOutputStream outStream = null; try { inStream = new FileInputStream(source); outStream = new FileOutputStream(target); in = inStream.getChannel(); out = outStream.getChannel(); in.transferTo(0, in.size(), out); } catch (IOException e) { e.printStackTrace(); } finally { close(inStream); close(in); close(outStream); close(out); } }
如果需要监测复制进度,可以用第二快的方法(留意buffer的大小,对速度有很大影响):
- private static void nioBufferCopy(File source, File target) {
- FileChannel in = null;
- FileChannel out = null;
- FileInputStream inStream = null;
- FileOutputStream outStream = null;
- try {
- inStream = new FileInputStream(source);
- outStream = new FileOutputStream(target);
- in = inStream.getChannel();
- out = outStream.getChannel();
- ByteBuffer buffer = ByteBuffer.allocate(4096);
- while (in.read(buffer) != -1) {
- buffer.flip();
- out.write(buffer);
- buffer.clear();
- }
- } catch (IOException e) {
- e.printStackTrace();
- } finally {
- close(inStream);
- close(in);
- close(outStream);
- close(out);
- }
- }
private static void nioBufferCopy(File source, File target) { FileChannel in = null; FileChannel out = null; FileInputStream inStream = null; FileOutputStream outStream = null; try { inStream = new FileInputStream(source); outStream = new FileOutputStream(target); in = inStream.getChannel(); out = outStream.getChannel(); ByteBuffer buffer = ByteBuffer.allocate(4096); while (in.read(buffer) != -1) { buffer.flip(); out.write(buffer); buffer.clear(); } } catch (IOException e) { e.printStackTrace(); } finally { close(inStream); close(in); close(outStream); close(out); } }
常用的方法1是:
- private static void customBufferBufferedStreamCopy(File source, File target) {
- InputStream fis = null;
- OutputStream fos = null;
- try {
- fis = new BufferedInputStream(new FileInputStream(source));
- fos = new BufferedOutputStream(new FileOutputStream(target));
- byte[] buf = new byte[4096];
- int i;
- while ((i = fis.read(buf)) != -1) {
- fos.write(buf, 0, i);
- }
- }
- catch (Exception e) {
- e.printStackTrace();
- } finally {
- close(fis);
- close(fos);
- }
- }
private static void customBufferBufferedStreamCopy(File source, File target) { InputStream fis = null; OutputStream fos = null; try { fis = new BufferedInputStream(new FileInputStream(source)); fos = new BufferedOutputStream(new FileOutputStream(target)); byte[] buf = new byte[4096]; int i; while ((i = fis.read(buf)) != -1) { fos.write(buf, 0, i); } } catch (Exception e) { e.printStackTrace(); } finally { close(fis); close(fos); } }
常用的方法2是:
- private static void customBufferStreamCopy(File source, File target) {
- InputStream fis = null;
- OutputStream fos = null;
- try {
- fis = new FileInputStream(source);
- fos = new FileOutputStream(target);
- byte[] buf = new byte[4096];
- int i;
- while ((i = fis.read(buf)) != -1) {
- fos.write(buf, 0, i);
- }
- }
- catch (Exception e) {
- e.printStackTrace();
- } finally {
- close(fis);
- close(fos);
- }
- }