Java: 复制文件最快方法

原文地址：
http://webcenterol.iteye.com/blog/1231259
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);
}
}