• ReaderIn

package ch03_reader;

import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;

public class ReaderIn {
	
	public static void main(String[] args) throws IOException {
		
		File path = new File(File.separator + "Users" + File.separator + "simpangyo" + File.separator + "FinTech_SPG" + File.separator + "IOjava");
		if(path.exists() == false) {
			path.mkdir();
			System.out.println("폴더 생성.");
		}
		
		File mf = new File(path, "reader.txt");
		if(mf.createNewFile()) {
			System.out.println(mf.getName() + "생성.");
		} else {
			System.out.println(mf.getName() + " 파일이 이미 있습니다.");
		}
		
		// 데이터 전송 통로 생성
		FileInputStream fis = new FileInputStream(mf);
		BufferedInputStream bis = new BufferedInputStream(fis);
		DataInputStream dis = new DataInputStream(bis);
		
		int ia = dis.readInt();
		double dd = dis.readDouble();
		String sd = dis.readUTF();
		
		System.out.println("ia : " + ia);
		System.out.println("dd : " + dd);
		System.out.println("sd : " + sd);
		
		dis.close();
	}
}

• ReaderOut

package ch03_reader;

import java.io.BufferedOutputStream;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class ReaderOut {
	
	public static void main(String[] args) throws IOException {
		
		File path = new File(File.separator + "Users" + File.separator + "simpangyo" + File.separator + "FinTech_SPG" + File.separator + "IOjava");
		if(path.exists() == false) {
			path.mkdir();
			System.out.println("폴더 생성.");
		}
		
		File mf = new File(path, "reader.txt");
		if(mf.createNewFile()) {
			System.out.println(mf.getName() + " 생성.");
		} else {
			System.out.println(mf.getName() + " 파일이 이미 있습니다.");
		}
		
		// 데이터 전송 통로 생성
		FileOutputStream fos = new FileOutputStream(mf);
		BufferedOutputStream bos = new BufferedOutputStream(fos);
		DataOutputStream dos = new DataOutputStream(bos);
		
		dos.writeInt(123);
		dos.writeDouble(5.6);
		dos.writeUTF("buffer 데이터");
		
		dos.close();
		
	}
}