package test;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Date;

public class NIOExample
{
	public static void doByteBufferStuffWithWrap()
	{
		byte[] message = {'H', 'o', 'w', 'd', 'y', '!'};
		ByteBuffer buffer = ByteBuffer.wrap(message);

		//buffer.flip();  don't do a flip
		int limit = buffer.limit();  //how many chars in buffer
		for (int i=0; i < limit; i++)
			System.out.print((char)buffer.get());
	}

	public static void doByteBufferStuffWithAllocate()
	{
		ByteBuffer buffer = ByteBuffer.allocate(10000);
		byte[] message = {'H', 'o', 'w', 'd', 'y'};
		buffer.put(message);
		buffer.put((byte) '!');

		buffer.flip();  //now flip over to reading from buffer
		int limit = buffer.limit();  //how many chars in buffer
		for (int i=0; i < limit; i++)
			System.out.print((char)buffer.get());
	}

	public static void doByteBufferStuffWithAllocateDirect()
	{
		ByteBuffer buffer = ByteBuffer.allocateDirect(10000);
		byte[] message = {'H', 'o', 'w', 'd', 'y'};
		buffer.put(message);
		buffer.put((byte) '!');

		buffer.flip();  //now flip over to reading from buffer
		int limit = buffer.limit();  //how many chars in buffer
		for (int i=0; i < limit; i++)
			System.out.print((char)buffer.get());
	}

	public static void writeFile() throws IOException
	{
		boolean append = false;
		FileOutputStream fos = new FileOutputStream("c:/junk/junk.txt", append); 
		FileChannel fc = fos.getChannel(); 
		ByteBuffer buffer = ByteBuffer.allocate(1024);  //create buffer
		byte[] message = {'H', 'o', 'w', 'd', 'y'};
		for (int i=0; i < message.length; i++) 
		   buffer.put(message[i]); 
		buffer.flip(); 
		fc.write(buffer); 
		fc.close();
	}
	
	public static void writeTestFile(String filepath, int filesize) throws IOException
	{
		FileOutputStream fos = new FileOutputStream(filepath); 
		FileChannel fc = fos.getChannel(); 
		ByteBuffer buffer = ByteBuffer.allocate(filesize);  //create buffer
		byte data[] = new byte[filesize];
		for (int i=0; i < data.length; i++)
		{
			data[i] = 'h';
			buffer.put(data[i]);
		}
		
		buffer.flip(); 
		fc.write(buffer); 
		fc.close();
	}

	public static void readTestFileWithIO(String filepath, int numTimes) throws IOException
	{
		File file = new File(filepath);
		long length = file.length();
		char charBuffer[] = new char[(int)length];
		
		for (int i=0; i < numTimes; i++)
		{
			FileReader fis = new FileReader(filepath);
			BufferedReader bufReader = new BufferedReader(fis);
			bufReader.read(charBuffer);
			bufReader.close();
			
			System.out.println("IO loopCnt=" + i + ", 1st byte=" + charBuffer[0]);
		}
	}

	public static void readTestFileWithNIO(String filepath, int numTimes) throws IOException
	{
		File file = new File(filepath);
		long length = file.length();
		
		for (int i=0; i < numTimes; i++)
		{
			FileInputStream fin = new FileInputStream(filepath);
			FileChannel fc = fin.getChannel(); 
			ByteBuffer buffer = ByteBuffer.allocateDirect((int)length);   //create buffer
			fc.read(buffer);  //read from channel into buffer
			fc.close();
			
			buffer.flip();
			System.out.println("NIO loopCnt=" + i + ", 1st byte=" + (char)buffer.asCharBuffer().charAt(0));
		}
	}
	
	public static void main(String[] args) throws IOException
	{
		String filepath = "c:/junk/junk.dat";
		writeTestFile(filepath, 5000000);
		
		System.out.println("Start IO Read:" + new Date());
		readTestFileWithIO(filepath, 50);
		System.out.println("End IO:" + new Date() + "\n\n");

		System.out.println("Start NIO Read:" + new Date());
		readTestFileWithNIO(filepath, 50);
		System.out.println("End NIO:" + new Date() + "\n\n");

		System.out.println("Exiting program...");
	}

}