Java复制文件的几种方法

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);
    }
}