Java实现按行读取大文件

非频繁操作如下：

String file = "F:" + File.separator + "a.txt";
FileInputStream fis = new FileInputStream(file);
RandomAccessFile raf = new RandomAccessFile(new File(file),"r");
String s ;
while((s =raf.readLine())!=null){
System.out.println(s);
}
raf.close();
fis.close();

可考虑bufferedinputstream和bufferedoutputstream来字节读取，上面这个代码太简单了，适用于非频繁操作。可以采用nio的FileChannel，比较适合于高并发操作，如下为filechannel的部分代码：

File inFile = new File("D:\\error");
 File outFile = new File("D:\\to.txt");
  
 FileChannel inFileChannel = new FileInputStream(inFile).getChannel();
 FileChannel outFileChannel = new FileOutputStream(outFile).getChannel();
  
 ByteBuffer buffer = ByteBuffer.allocate(1024);
 while(-1 != inFileChannel.read(buffer)){
  buffer.flip();
  outFileChannel.write(buffer);
  buffer.clear();
 }
 outFileChannel.close();
 inFileChannel.close();

参考：https://www.jb51.net/article/66021.htm