FileChannel

import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.nio.charset.Charset;
import org.junit.Test;
public class FileChannelInTest {

	@Test
	public void testFileRead1() throws Exception{
		Charset charset = Charset.forName("utf-8");
		RandomAccessFile aFile = new RandomAccessFile("D:/dump01.txt", "rw");
		FileChannel inChannel = aFile.getChannel();
//		从FileChannel中读取数据
		ByteBuffer byteBuffer = ByteBuffer.allocate(48);
		long start = System.currentTimeMillis();
		String read = "";
		while (true) {
			int eof = inChannel.read(byteBuffer);
			if (eof == -1)
				break;
			byteBuffer.flip();
			read = charset.decode(byteBuffer)+"";
			System.out.print(read);
			byteBuffer.clear();
		}
		System.out.println("spending : " + (System.currentTimeMillis()-start));
		inChannel.close();
		aFile.close();
	}
	
	@Test
	public void testFileRead2() throws Exception{
		RandomAccessFile aFile = new RandomAccessFile("D:/dump01.txt", "rw");
		FileChannel inChannel = aFile.getChannel();
		ByteBuffer buf = ByteBuffer.allocate(48);
		int bytesRead = inChannel.read(buf);
		while (bytesRead != -1) {
			System.out.println("Read " + bytesRead);
			buf.flip();
			while (buf.hasRemaining()) {
				System.out.print((char) buf.get());
			}
			buf.clear();
			bytesRead = inChannel.read(buf);
		}
		aFile.close();
	}
	
}

 

import java.io.RandomAccessFile;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import org.junit.Test;

public class FileChannelOutTest {

	@Test
	public void testFileWrite1() throws Exception{
		String newData = "New String to write to file..." + System.currentTimeMillis();
		RandomAccessFile aFile = new RandomAccessFile("D:/channelOutTest.txt", "rw");
		FileChannel outChannel = aFile.getChannel();
		ByteBuffer buf = ByteBuffer.allocate(48);
		buf.clear();
		buf.put(newData.getBytes());
		buf.flip();
		while(buf.hasRemaining()) {
			outChannel.write(buf);
		}
		aFile.close();
	}
	
}