import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
public class TestNio {
public static void main(String args[]) throws Exception{
//String infile = "D:\\workspace\\test\\usagetracking.log";
//FileInputStream fin= new FileInputStream(infile);
//FileChannel fcin = fin.getChannel();
int bufSize = 100;
File fin = new File("D:\\workspace\\test\\usagetracking.log");
File fout = new File("D:\\workspace\\test\\usagetracking2.log");
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];
int size = 0;
StringBuffer strBuf = new StringBuffer("");
//while((size = fcin.read(buffer)) != -1){
while(fcin.read(rBuffer) != -1){
int rSize = rBuffer.position();
rBuffer.rewind();
rBuffer.get(bs);
rBuffer.clear();
String tempString = new String(bs, 0, rSize);
//System.out.print(tempString);
//System.out.print("<200>");
int fromIndex = 0;
int endIndex = 0;
while((endIndex = tempString.indexOf(enterStr, fromIndex)) != -1){
String line = tempString.substring(fromIndex, endIndex);
line = new String(strBuf.toString() + line);
//System.out.print(line);
//System.out.print("</over/>");
//write to anthone file
writeFileByLine(fcout, wBuffer, 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) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public static void writeFileByLine(FileChannel fcout, ByteBuffer wBuffer, String line){
try {
//write on file head
//fcout.write(wBuffer.wrap(line.getBytes()));
//wirte append file on foot
fcout.write(wBuffer.wrap(line.getBytes()), fcout.size());
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}