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import java.io.File;
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import java.io.IOException;
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import java.io.RandomAccessFile;
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import java.nio.ByteBuffer;
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import java.nio.channels.FileChannel;
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public class TestNio {
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public static void main(String args[]) throws Exception {
- System.err.println("begin");
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long start = System.currentTimeMillis();
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int _5M = 1024*1024*5;
- File fin = new File("D:\\debug.log");
- File fout = new File("D:\\debug-bak.log");
- FileChannel fcin = new RandomAccessFile(fin, "r").getChannel();
- ByteBuffer rBuffer = ByteBuffer.allocate(_5M);
- FileChannel fcout = new RandomAccessFile(fout, "rws").getChannel();
- ByteBuffer wBuffer = ByteBuffer.allocateDirect(_5M);
- readFileByLine(_5M, fcin, rBuffer, fcout, wBuffer);
- System.err.print((System.currentTimeMillis() - start) /1000);
- }
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public static void readFileByLine(int bufSize, FileChannel fcin,
- ByteBuffer rBuffer, FileChannel fcout, ByteBuffer wBuffer) {
- String enterStr = "\n";
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try {
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byte[] bs = new byte[bufSize];
- StringBuilder strBuf = new StringBuilder("");
- String tempString = null;
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while (fcin.read(rBuffer) != -1) {
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int rSize = rBuffer.position();
- rBuffer.rewind();
- rBuffer.get(bs);
- rBuffer.clear();
- tempString = new String(bs, 0, rSize);
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int fromIndex = 0;
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int endIndex = 0;
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while ((endIndex = tempString.indexOf(enterStr, fromIndex)) != -1) {
- String line = tempString.substring(fromIndex, endIndex);
- line = strBuf.toString() + line;
- writeFileByLine(fcout, wBuffer, line);
- strBuf.delete(0, strBuf.length());
- fromIndex = endIndex + 1;
- }
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if (rSize > tempString.length()) {
- strBuf.append(tempString.substring(fromIndex,
- tempString.length()));
- } else {
- strBuf.append(tempString.substring(fromIndex, rSize));
- }
- }
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- } catch (IOException e) {
- e.printStackTrace();
- }
- }
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public static void writeFileByLine(FileChannel fcout, ByteBuffer wBuffer,
- String line) {
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try {
- fcout.write(wBuffer.wrap(line.getBytes()), fcout.size());
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- }