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);
    }
}