Java文件复制多种方法

1、InputStream与OutputStream 

创建两个文件 - 源和目标。然后我们从源创建InputStream并使用OutputStream将其写入目标文件进行 java 复制文件操作。

private 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 {is.close();os.close();}
}

2、Apache Commons IO FileUtils

copyFile(File srcFile, File destFile)可用于在 java 中复制文件。如果您已经在项目中使用 Apache Commons IO，那么使用它来简化代码是有意义的。它在内部使用 Java NIO FileChannel，因此如果您尚未将其用于其他功能，则可以避免使用此包装器方法。下面是使用apache commons io进行java复制文件操作的方法

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

3、Files类的copy()方法在 java 中复制文件

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

4、使用BufferedInputStream/BufferedOutputStream高效字节流进行复制文件

private static void bufferedStreamCopyFile(File srcFile, File desFile) throwsIOException {//使用缓冲字节流进行文件复制BufferedInputStream bis = new BufferedInputStream(newFileInputStream(srcFile));BufferedOutputStream bos = new BufferedOutputStream(newFileOutputStream(desFile));byte[] b = new byte[1024];Integer len = 0;//一次读取1024字节的数据while((len = bis.read(b)) != -1) {bos.write(b, 0, len);}bis.close();bos.close();
}

5、使用FileReader/FileWriter字符流进行文件复制

注意这种方式只能复制只包含字符的文件，也就意味着你用记事本打开该文件你能够读懂

private static void readerWriterCopyFile(File srcFile, File desFile) throwsIOException  {//使用字符流进行文件复制，注意：字符流只能复制只含有汉字的文件FileReader fr = newFileReader(srcFile);FileWriter fw = newFileWriter(desFile);Integer by = 0;while((by = fr.read()) != -1) {fw.write(by);}fr.close();fw.close();}

6、使用BufferedReader/BufferedWriter高效字符流进行文件复制

意这种方式只能复制只包含字符的文件，也就意味着你用记事本打开该文件你能够读懂

private static void bufferedReaderWriterCopyFile(File srcFile, File desFile)  throwsIOException {//使用带缓冲区的高效字符流进行文件复制BufferedReader br = new BufferedReader(newFileReader(srcFile));BufferedWriter bw = new BufferedWriter(newFileWriter(desFile));char[] c = new char[1024];Integer len = 0;while((len = br.read(c)) != -1) {bw.write(c, 0, len);}//方式二/*String s = null;while((s = br.readLine()) != null) {bw.write(s);bw.newLine();}*/br.close();bw.close();}

7、使用BufferedReader/BufferedWriter高效字符流进行文件复制

注意这种方式只能复制只包含字符的文件，也就意味着你用记事本打开该文件你能够读懂

private static void bufferedReaderWriterCopyFile(File srcFile, File desFile)  throwsIOException {//使用带缓冲区的高效字符流进行文件复制BufferedReader br = new BufferedReader(newFileReader(srcFile));BufferedWriter bw = new BufferedWriter(newFileWriter(desFile));char[] c = new char[1024];Integer len = 0;while((len = br.read(c)) != -1) {bw.write(c, 0, len);}//方式二/*String s = null;while((s = br.readLine()) != null) {bw.write(s);bw.newLine();}*/br.close();bw.close();
}

8、使用FileChannel复制

Java NIO包括transferFrom方法,根据文档应该比文件流复制的速度更快

private static void copyFileUsingFileChannels(File source, File dest) throws IOException {   FileChannel inputChannel = null;   FileChannel outputChannel = null;   try { inputChannel = new FileInputStream(source).getChannel(); outputChannel = new FileOutputStream(dest).getChannel(); outputChannel.transferFrom(inputChannel, 0, inputChannel.size()); } finally { inputChannel.close(); outputChannel.close(); } 
}