NIO没有BufferedReader这样读取行的方法。
可以查找ByteBuffer最后一个换行符,在换行符之后的数据，重新放回ByteBuffer

import java.io.FileInputStream;

import java.io.IOException;

import java.io.UnsupportedEncodingException;

import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

import java.nio.charset.Charset;

interface Callback {

    void action(String line);

}

public class NIOReadline {

    private int buffersize;

    private Charset charset ;

    private Callback callback;

    private FileChannel channel;

    ByteBuffer buffer ;

    public NIOReadline(String file, Callback callback) throws UnsupportedEncodingException, IOException {

        this(file,callback,200,Charset.defaultCharset().displayName());

    }



    public NIOReadline(String file, Callback callback,int bufferSize,String charsetName) throws UnsupportedEncodingException, IOException {

        charset=Charset.forName(charsetName);

        buffersize=bufferSize;

        channel = new FileInputStream(file).getChannel();

        buffer=ByteBuffer.allocate(bufferSize);

        this.callback=callback;

        action();

    }

    private void action() throws UnsupportedEncodingException, IOException {

        while (channel.read(buffer) > 0) {

            buffer.flip();

            byte[] data = new byte[buffersize];

            // 数组最后一个可用数据

            int last = buffer.limit() - 1;

            buffer.get(data, 0, buffer.limit());

            buffer.compact();

            // 找最后一个换行符

            int i = last;

            while (data[i] != (byte) '\n') {

                i = i - 1;

                // 如果没有换行符,直接退出,可能是最后一行

                if (i < 0) {

                    break;

                }

            }

            if (i > 0) {

                // 如果有换行符

                action(new String(data, 0, i + 1, charset));

                while (i < last) {

                    buffer.put(data[i + 1]);

                    i++;

                }

            } else {

                action(new String(data, 0, buffer.limit(), charset));

            }

        }

        channel.close();

    }

    private void action(String str) {

        String[] data = str.split("\n");

        for (String line : data) {

            callback.action(line);

        }

    }

    public static void main(String[] args) throws UnsupportedEncodingException, IOException {

        NIOReadline r=new NIOReadline("C:\\Users\\new\\Desktop\\test.sql", new Callback() {



            @Override

            public void action(String line) {

                System.out.print(line);

            }

        });

    }

}

这个方法可以解决使用ByteBuffer造成的文本截断问题。

ITPub博客

ByteBuffer按行处理数据(readline)

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