Java NIO逐行读文件并写文件

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package com.sogou.study.nio.file;/** * Created by denglinjie on 2016/9/27. */import java.io.File;import java.io.IOException;import java.io.RandomAccessFile;import java.nio.ByteBuffer;import java.nio.channels.FileChannel;public class TestFileNio {    public static void main(String args[]) throws Exception{        int bufSize = 100;        File fin = new File("D:\\test\\file1.txt");        File fout = new File("D:\\test\\file2.txt");        FileChannel fcin = new RandomAccessFile(fin, "r").getChannel();        ByteBuffer rBuffer = ByteBuffer.allocate(bufSize);        FileChannel fcout = new RandomAccessFile(fout, "rws").getChannel();        ByteBuffer wBuffer = ByteBuffer.allocateDirect(bufSize);        readFileByLine(bufSize, fcin, rBuffer, fcout, wBuffer);        System.out.print("OK!!!");    }    public static void readFileByLine(int bufSize, FileChannel fcin, ByteBuffer rBuffer, FileChannel fcout, ByteBuffer wBuffer){        String enterStr = "\n";        try{            byte[] bs = new byte[bufSize];            StringBuffer strBuf = new StringBuffer("");            while(fcin.read(rBuffer) != -1){                int rSize = rBuffer.position();                rBuffer.rewind();<span style="white-space:pre"></span>//将position置为0，为读做准备                rBuffer.get(bs);<span style="white-space:pre"></span>//从上述position=0的位置开始读                rBuffer.clear();                String tempString = new String(bs, 0, rSize);                int fromIndex = 0;                int endIndex = 0;                //查找换行符符号\n，如果找到了，则写文件，如果没有找到则继续读取                while((endIndex = tempString.indexOf(enterStr, fromIndex)) != -1){                    String line = tempString.substring(fromIndex, endIndex);                    line = strBuf.toString() + line;                    writeFileByLine(fcout, line);                    strBuf.delete(0, strBuf.length());                    fromIndex = endIndex + 1;                }                if(rSize > tempString.length()){                    strBuf.append(tempString.substring(fromIndex, tempString.length()));                }else{                    strBuf.append(tempString.substring(fromIndex, rSize));                }            }        } catch (IOException e) {            e.printStackTrace();        }    }    public static void writeFileByLine(FileChannel fcout, String line){        try {            fcout.write(ByteBuffer.wrap(line.getBytes()), fcout.size());        } catch (IOException e) {            e.printStackTrace();        }    }}

上述代码中所用到的ByteBuffer，关于它的介绍参考如下链接，用图解的方式解释的非常形象：

http://blog.csdn.net/baple/article/details/12749005

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