在jdk1.7之前，java中没有直接的类提供文件复制功能。下面就文件复制，提出几种方案。

jdk1.7中的文件复制

在jdk1.7版本中可以直接使用Files.copy(File srcFile, File destFile)方法即可。

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private static void copyFileUsingJava7Files(File source, File dest) throws IOException {
    Files.copy(source.toPath(), dest.toPath());
}

使用FileInputStream复制

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public static void copyFileUsingStream(File source, File dest) throws IOException {
    InputStream is = null;
    OutputStream os = null;
    try {
        is = new FileInputStream(source);
        os = new FileOutputStream(dest);
        byte[] buffer = new byte[1024];
        int length;
        while ((length = is.read(buffer)) > 0) {
            os.write(buffer, 0, length);
        }
    } finally {
        if (is != null) {
            is.close();
        }
        if (os != null) {
            os.close();
        }
    }
}

使用FileChannel实现复制

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public static void copyFileUsingChannel(File source, File dest) throws IOException {
    FileChannel sourceChannel = null;
    FileChannel destChannel = null;
    try {
        sourceChannel = new FileInputStream(source).getChannel();
        destChannel = new FileOutputStream(dest).getChannel();
        destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
    } finally {
        if (sourceChannel != null) {
            sourceChannel.close();
        }
        if (destChannel != null) {
            destChannel.close();
        }
    }
}

使用Apache Commons IO包中的FileUtils.copyFile复制

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public static void copyFileUsingApacheIO(File source, File dest) throws IOException {
    FileUtils.copyFile(source, dest);
}

使用IO重定向实现复制

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public static void copyFileUsingRedirection(File source, File dest) throws IOException {
    FileInputStream in = null;
    PrintStream out = null;
    try {
        in = new FileInputStream(source);
        out = new PrintStream(dest);
        System.setIn(in);
        System.setOut(out);
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            System.out.println(sc.nextLine());
        }
    } finally {
        if (in != null) {
            in.close();
        }
        if (out != null) {
            out.close();
        }
    }
}