将给定输入文件的内容复制到新的字节数组中。

//N o w  J a v a  . c o m

import java.io.BufferedInputStream;

import java.io.BufferedOutputStream;

import java.io.BufferedReader;

import java.io.BufferedWriter;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.FileReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.io.Reader;

import java.io.StringWriter;

import java.io.Writer;


public class Main{

    public static final int BUFFER_SIZE = 4096;

    /**

     * Copy the contents of the given input File into a new byte array.

     * 

     * @param in

     *            the file to copy from

     * @return the new byte array that has been copied to

     * @throws IOException

     *             in case of I/O errors

     *//*时代Java公众号 - N o w J a  v a . c o m 提 供*/

    public static byte[] copyToByteArray(final File in) throws IOException {

        Assert.notNull(in, "No input File specified");

        return copyToByteArray(new BufferedInputStream(new FileInputStream(

                in)));

    }

    /**

     * Copy the contents of the given InputStream into a new byte array. Closes

     * the stream when done.

     * 

     * @param in

     *            the stream to copy from

     * @return the new byte array that has been copied to

     * @throws IOException

     *             in case of I/O errors

     */

    public static byte[] copyToByteArray(final InputStream in)

            throws IOException {

        final ByteArrayOutputStream out = new ByteArrayOutputStream(

                BUFFER_SIZE);

        copy(in, out);

        return out.toByteArray();

    }

    /**

     * Copy the contents of the given input File to the given output File.

     * 

     * @param in

     *            the file to copy from

     * @param out

     *            the file to copy to

     * @return the number of bytes copied

     * @throws IOException

     *             in case of I/O errors

     */

    public static int copy(final File in, final File out)

            throws IOException {

        Assert.notNull(in, "No input File specified");

        Assert.notNull(out, "No output File specified");

        return copy(new BufferedInputStream(new FileInputStream(in)),

                new BufferedOutputStream(new FileOutputStream(out)));

    }

    /**

     * Copy the contents of the given byte array to the given output File.

     * 

     * @param bytes

     *            the byte array to copy from

     * @param file

     *            the file to copy to

     * @throws IOException

     *             in case of I/O errors

     */

    public static void copy(final byte[] bytes, final File file)

            throws IOException {

        Assert.notNull(bytes, "No input byte array specified");

        Assert.notNull(file, "No output File specified");

        final ByteArrayInputStream in = new ByteArrayInputStream(bytes);

        final OutputStream out = new BufferedOutputStream(

                new FileOutputStream(file));

        copy(in, out);

    }

    /**

     * Copy the contents of the given InputStream to the given OutputStream.

     * Closes both streams when done.

     * 

     * @param in

     *            the stream to copy from

     * @param out

     *            the stream to copy to

     * @return the number of bytes copied

     * @throws IOException

     *             in case of I/O errors

     */

    public static int copy(InputStream in, OutputStream out)

            throws IOException {

        Assert.notNull(in, "No InputStream specified");

        Assert.notNull(out, "No OutputStream specified");

        if (!(in instanceof BufferedInputStream)) {

            in = new BufferedInputStream(in);

        }

        if (!(out instanceof BufferedOutputStream)) {

            out = new BufferedOutputStream(out);

        }

        try {

            int byteCount = 0;

            final byte[] buffer = new byte[BUFFER_SIZE];

            int bytesRead = -1;

            while ((bytesRead = in.read(buffer)) != -1) {

                out.write(buffer, 0, bytesRead);

                byteCount += bytesRead;

            }

            out.flush();

            return byteCount;

        } finally {

            IOUtils.closeQuietly(in, out);

        }

    }

    /**

     * Copy the contents of the given byte array to the given OutputStream.

     * Closes the stream when done.

     * 

     * @param bytes

     *            the byte array to copy from

     * @param out

     *            the OutputStream to copy to

     * @throws IOException

     *             in case of I/O errors

     */

    public static void copy(final byte[] bytes, final OutputStream out)

            throws IOException {

        Assert.notNull(bytes, "No input byte array specified");

        Assert.notNull(out, "No OutputStream specified");

        try {

            out.write(bytes);

        } finally {

            IOUtils.closeQuietly(out);

        }

    }

    /**

     * Copy the contents of the given Reader to the given Writer. Closes both

     * when done.

     * 

     * @param in

     *            the Reader to copy from

     * @param out

     *            the Writer to copy to

     * @return the number of characters copied

     * @throws IOException

     *             in case of I/O errors

     */

    public static int copy(Reader in, Writer out) throws IOException {

        Assert.notNull(in, "No Reader specified");

        Assert.notNull(out, "No Writer specified");

        if (!(in instanceof BufferedReader)) {

            in = new BufferedReader(in);

        }

        if (!(out instanceof BufferedWriter)) {

            out = new BufferedWriter(out);

        }

        try {

            int byteCount = 0;

            final