public static long copy(final InputStream input, final OutputStream output,
			final int bufferSize) throws IOException {
		return copyLarge(input, output, new byte[bufferSize]);
	}
Copies bytes from an <code>InputStream</code> to an <code>OutputStream</code> using
an internal buffer of the given size.
<p>
This method buffers the input internally, so there is no need to use a
<code>BufferedInputStream</code>.
<p>
@param input the <code>InputStream</code> to read from
@param output the <code>OutputStream</code> to write to
@param bufferSize the bufferSize used to copy from the input to the output
@return the number of bytes copied
@throws NullPointerException if the input or output is null
@throws IOException if an I/O error occurs
@since 2.5
spring-cloud-alibaba-starters/spring-cloud-alibaba-commons/src/main/java/com/alibaba/cloud/commons/io/IOUtils.java