SHA-1 Calculator FX (JavaFX) / http://inaz2.hatenablog.com/entry/2016/04/26/203308

Main.java

package application;
	
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.concurrent.Task;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.control.cell.TextFieldTableCell;
import javafx.scene.input.DragEvent;
import javafx.scene.input.Dragboard;
import javafx.scene.input.TransferMode;
import javafx.scene.layout.BorderPane;
import javafx.stage.Stage;


public class Main extends Application {
	private final TableView<FileInfo> table = new TableView<>();

	@Override
	@SuppressWarnings("unchecked")
	public void start(Stage primaryStage) {
		try {
			BorderPane root = new BorderPane();
			Scene scene = new Scene(root,600,400);  // expanded default size
			scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
			primaryStage.setScene(scene);
			primaryStage.setTitle("SHA-1 Calculator FX");
			
			// TableView settings
			table.setEditable(true);
			table.setColumnResizePolicy(TableView.CONSTRAINED_RESIZE_POLICY);

			TableColumn<FileInfo, String> filePathCol = new TableColumn<>("File Path");
			filePathCol.setCellValueFactory(new PropertyValueFactory<>("path"));
			filePathCol.setCellFactory(TextFieldTableCell.forTableColumn());

			TableColumn<FileInfo, String> sha1sumCol = new TableColumn<>("sha1sum");
			sha1sumCol.setCellValueFactory(new PropertyValueFactory<>("sha1sum"));
			sha1sumCol.setCellFactory(TextFieldTableCell.forTableColumn());

			table.getColumns().addAll(filePathCol, sha1sumCol);
			ObservableList<FileInfo> data = FXCollections.observableArrayList();
			table.setItems(data);

			root.setCenter(table);

			// enable file drop
			scene.setOnDragOver(new DragOverHandler());
			scene.setOnDragDropped(new DragDroppedHandler());
			
			primaryStage.show();
		} catch(Exception e) {
			e.printStackTrace();
		}
	}
	
	public static void main(String[] args) {
		launch(args);
	}
	
	private class DragOverHandler implements EventHandler<DragEvent> {
		@Override
		public void handle(DragEvent event) {
			Dragboard db = event.getDragboard();
			if (db.hasFiles()) {
				event.acceptTransferModes(TransferMode.COPY);
			} else {
				event.consume();
			}
		}
	}

	private class DragDroppedHandler implements EventHandler<DragEvent> {
		@Override
		public void handle(DragEvent event) {
			Dragboard db = event.getDragboard();
			boolean success = false;
			if (db.hasFiles()) {
				success = true;
				ObservableList<FileInfo> data = table.getItems();
				for (File file : db.getFiles()) {
					FileInfo fileinfo = new FileInfo(file.getAbsolutePath(), "");
					data.add(fileinfo);
					SHA1CalculationTask task = new SHA1CalculationTask(fileinfo);
					fileinfo.sha1sumProperty().bind(task.messageProperty());
					new Thread(task).start();
				}
			}
			event.setDropCompleted(success);
			event.consume();
		}
	}

	class SHA1CalculationTask extends Task<Void> {
		private final FileInfo fileinfo;

		public SHA1CalculationTask(FileInfo fileinfo) {
			this.fileinfo = fileinfo;
		}

		@Override
		protected Void call() throws Exception {
			MessageDigest md = null;
			try {
				md = MessageDigest.getInstance("SHA-1");
			} catch (NoSuchAlgorithmException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}

			// update digest with each 8MB chunk
			String path = fileinfo.getPath();
			long totalBytes = (new File(path)).length();
			long currentBytes = 0;
			try (FileInputStream istream = new FileInputStream(path)) {
				byte[] buf = new byte[8*1024*1024];
				int n;
				while ((n = istream.read(buf, 0, buf.length)) != -1) {
					md.update(Arrays.copyOf(buf, n));
					currentBytes += n;
					String message = String.format("calculating %d%%...", 100 * currentBytes / totalBytes);
					updateMessage(message);
				}
			} catch (IOException e) {
				e.printStackTrace();
			}

			byte[] digest = md.digest();
			StringBuilder sb = new StringBuilder();
			for (byte b : digest) {
				sb.append(String.format("%02x", b));
			}
			updateMessage(sb.toString());
			return null;
		}
	}


	public static class FileInfo {
		private final SimpleStringProperty path = new SimpleStringProperty();
		private final SimpleStringProperty sha1sum = new SimpleStringProperty();

		private FileInfo(String path, String sha1sum) {
			setPath(path);
			setSha1sum(sha1sum);
		}

		public String getPath() {
			return path.get();
		}

		public void setPath(String newPath) {
			path.set(newPath);
		}

		public String getSha1sum() {
			return sha1sum.get();
		}

		public void setSha1sum(String newSha1sum) {
			sha1sum.set(newSha1sum);
		}

		public SimpleStringProperty sha1sumProperty() {
			return sha1sum;
		}
	}
}

SHA1CalculatorFX.jar