Runnable을 활용한 파일의 해시값 계산

package jce;

import java.io.FileInputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;

public class InstanceCallbackDigest implements Runnable{
	private String filename;
	private InstanceCallbackDigestUserInterface callback;
	
	public InstanceCallbackDigest(String filename, InstanceCallbackDigestUserInterface callback) {
		this.filename = filename;
		this.callback = callback;
	}
	
	@Override
	public void run() {
		try {
			FileInputStream in  = new FileInputStream(filename);
			MessageDigest sha = MessageDigest.getInstance("SHA-256");
			DigestInputStream din  = new DigestInputStream(in, sha);
			while(din.read() != -1);//파일 전체를 읽는다.
			din.close();
			byte[] digest = sha.digest();
			callback.receveDigest(digest);
		} catch (Exception e) {
			System.err.println(e);
		}
		
			
	}
	
}

package jce;

import java.util.Arrays;

import javax.swing.plaf.synth.SynthScrollBarUI;
import javax.xml.bind.DatatypeConverter;

public class InstanceCallbackDigestUserInterface {
	private String filename;
	private byte[] digest;
	
	public InstanceCallbackDigestUserInterface(String filename) {
		super();
		this.filename = filename;
	}
	
	public void calculateDigest(){
		InstanceCallbackDigest cb = new InstanceCallbackDigest(filename, this);
		Thread t = new Thread(cb);
		t.start();
	}
	
	void receveDigest (byte[] digest){
		this.digest = digest;
		System.out.println(this);
	}

	@Override
	public String toString() {
		String result = filename+": ";
		if(digest != null){
			result+= DatatypeConverter.printHexBinary(digest);
		}else{
			result += "digest not available";
		}
		
		return result;
	}
	public static void main(String[] args) {
		for(String filename: args){
			//다이제스트 계산 
			InstanceCallbackDigestUserInterface d = new InstanceCallbackDigestUserInterface(filename);
			d.calculateDigest();
		}
	}
	
}