Java: 复制文件最快方法

最新推荐文章于 2024-06-07 13:28:53 发布

最新推荐文章于 2024-06-07 13:28:53 发布 · 74 阅读

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本文介绍了几种文件复制方法，包括最快的NIO传输复制方法，这种方法利用了Java NIO的FileChannel进行直接的数据传输，适用于大文件复制场景。此外还介绍了第二种较快的方法，使用ByteBuffer进行缓冲区读写操作，并提供了两种常用的文件复制实现。

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); } }

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); } }

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); } }

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); } }