, GUI, , JPanel, , - ( ..) (GUI). " JFileChooser actionPerformed... [ DrawingPanel, JPanel], .

, .

1: JFileChooser. :

// first make sure that you've declared the JFrame frame as final
int result = theFileChooser.showOpenDialog(frame); 
if (result == JFileChooser.APPROVE_OPTION) {
  // ... code goes here           
}

2

Swing:

, MVC Model-View-Control, , . , , , - JTextField, .

MvcMain

import javax.swing.SwingUtilities;

public class MvcMain {

   private static void createAndShowGui() {
      MvcView view = new ShowTextView("Show Text");
      MvcModel model = new ShowTextModel();
      ShowTextControl control = new ShowTextControl(view, model);

      control.showView(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}

MvcModel

import java.beans.PropertyChangeListener;

public interface MvcModel {
   static final String TEXT = "text";
   static final String STATUS = "STATUS";

   String getText();

   String getStatus();

   void setText(String text);

   void setStatus(String text);

   void addPropertyChangeListener(PropertyChangeListener listener);

   void removePropertyChangeListener(PropertyChangeListener listener);
}

MvcView

import java.awt.Window;
import javax.swing.Action;

public interface MvcView {

   void setVisible(boolean visible);

   void setFileAction(Action fileAction);

   void setOpenFileAction(Action openFileAction);

   void setSaveToFileAction(Action saveToFileAction);

   void setExitAction(Action exitAction);

   void setStatusText(String string);

   String getTextAreaText();

   void setTextAreaText(String text);

   Window getTopWindow();

}

ShowTextView

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.Window;
import javax.swing.*;

public class ShowTextView implements MvcView {
   private JFrame frame = new JFrame();
   private JMenuBar menuBar = new JMenuBar();
   private JMenu fileMenu = new JMenu();
   private StatusBar statusBar = new StatusBar();
   private ViewDisplayText displayText = new ViewDisplayText();

   public ShowTextView(String title) {
      menuBar.add(fileMenu);

      frame.setTitle(title);
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(displayText.getMainComponent(), BorderLayout.CENTER);
      frame.getContentPane().add(statusBar.getComponent(), BorderLayout.PAGE_END);
      frame.setJMenuBar(menuBar);
   }

   @Override
   public void setVisible(boolean visible) {
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

   @Override
   public void setOpenFileAction(Action action) {
      displayText.setOpenFileButtonAction(action);
      fileMenu.add(new JMenuItem(action));
   }

   @Override
   public void setSaveToFileAction(Action action) {
      displayText.setSaveToFileAction(action);
      fileMenu.add(new JMenuItem(action));
   }

   @Override
   public void setExitAction(Action exitAction) {
      displayText.setExitAction(exitAction);
      fileMenu.add(new JMenuItem(exitAction));
   } 

   @Override
   public void setFileAction(Action fileAction) {
      fileMenu.setAction(fileAction);
   }


   @Override
   public String getTextAreaText() {
      return displayText.getTextAreaText();
   }

   @Override
   public void setTextAreaText(String text) {
      displayText.setTextAreaText(text);
   }

   @Override
   public Window getTopWindow() {
      return frame;
   }

   @Override
   public void setStatusText(String text) {
      statusBar.setText(text);
   }

}

class ViewDisplayText {
   private static final int TA_ROWS = 30;
   private static final int TA_COLS = 50;
   private static final int GAP = 2;
   private JPanel mainPanel = new JPanel();
   private JButton openFileButton = new JButton();
   private JButton saveToFileButton = new JButton();
   private JButton exitButton = new JButton();
   private JTextArea textArea = new JTextArea(TA_ROWS, TA_COLS);

   public ViewDisplayText() {
      JPanel buttonPanel = new JPanel(new GridLayout(1, 0, GAP, 0));
      buttonPanel.add(openFileButton);
      buttonPanel.add(saveToFileButton);
      buttonPanel.add(exitButton);

      mainPanel.setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
      mainPanel.setLayout(new BorderLayout());
      mainPanel.add(new JScrollPane(textArea), BorderLayout.CENTER);
      mainPanel.add(buttonPanel, BorderLayout.PAGE_END);
   }

   public void setExitAction(Action exitAction) {
      exitButton.setAction(exitAction);
   }

   public JComponent getMainComponent() {
      return mainPanel;
   }

   public void setOpenFileButtonAction(Action action) {
      openFileButton.setAction(action);
   }

   public void setSaveToFileAction(Action action) {
      saveToFileButton.setAction(action);
   }

   public String getTextAreaText() {
      return textArea.getText();
   }

   public void setTextAreaText(String text) {
      textArea.setText(text);
   }
}

class StatusBar {
   private static final String STATUS = "Status: ";
   private JLabel label = new JLabel(STATUS);

   public StatusBar() {
      label.setBorder(BorderFactory.createLineBorder(Color.black));
   }

   public JComponent getComponent() {
      return label;
   }

   public void setText(String text) {
      label.setText(STATUS + text);
   }
}

ShowTextModel

import java.beans.PropertyChangeListener;
import javax.swing.event.SwingPropertyChangeSupport;

public class ShowTextModel implements MvcModel {
   private String text;
   private String status;
   private SwingPropertyChangeSupport propChangeSupport = 
         new SwingPropertyChangeSupport(this);

   @Override
   public String getText() {
      return text;
   }

   @Override
   public void setText(String text) {
      String newValue = text;
      String oldValue = this.text;
      this.text = newValue;
      propChangeSupport.firePropertyChange(TEXT, oldValue, newValue);
   }

   @Override
   public void setStatus(String status) {
      String newValue = status;
      String oldValue = this.status;
      this.status = newValue;
      propChangeSupport.firePropertyChange(STATUS, oldValue, newValue);
   }

   @Override
   public void addPropertyChangeListener(PropertyChangeListener listener) {
      propChangeSupport.addPropertyChangeListener(listener);
   }

   @Override
   public void removePropertyChangeListener(PropertyChangeListener listener) {
      propChangeSupport.removePropertyChangeListener(listener);
   }

   @Override
   public String getStatus() {
      return status;
   }

}

ShowTextControl

import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import java.util.concurrent.ExecutionException;
import javax.swing.*;

public class ShowTextControl {

   private MvcView view;
   private MvcModel model;

   public ShowTextControl(MvcView view, MvcModel model) {
      this.view = view;
      this.model = model;

      view.setFileAction(new FileAction("File", KeyEvent.VK_F));
      view.setOpenFileAction(new OpenFileAction(view, model, "Open File",
            KeyEvent.VK_O));
      view.setSaveToFileAction(new SaveToFileAction(view, model,
            "Save to File", KeyEvent.VK_S));
      view.setExitAction(new ExitAction(view, model, "Exit", KeyEvent.VK_X));

      model.addPropertyChangeListener(new ModelListener(view, model));
   }

   public void showView(boolean visible) {
      view.setVisible(visible);
   }
}

@SuppressWarnings("serial")
class OpenFileAction extends AbstractAction {
   private MvcView view;
   private MvcModel model;

   public OpenFileAction(MvcView view, MvcModel model, String name, int keyCode) {
      super(name);
      putValue(MNEMONIC_KEY, keyCode);
      this.view = view;
      this.model = model;
   }

   @Override
   public void actionPerformed(ActionEvent evt) {
      JFileChooser fileChooser = new JFileChooser();
      fileChooser.setMultiSelectionEnabled(false);
      int result = fileChooser.showOpenDialog(view.getTopWindow());
      if (result == JFileChooser.APPROVE_OPTION) {
         File file = fileChooser.getSelectedFile();
         if (file.exists()) {
            if (file.getName().endsWith(".txt")) {
               model.setStatus("Opening file \"" + file.getName() + "\"");

               OpenFileWorker openFileWorker = new OpenFileWorker(file);
               openFileWorker.addPropertyChangeListener(
                     new OpenFileWorkerListener(model));
               openFileWorker.execute();
            } else {
               model.setStatus("File \"" + file.getName()
                     + "\" is not a text file");
            }
         } else {
            model.setStatus("File \"" + file.getName() + "\" does not exist");
         }
      }
   }

}

class OpenFileWorker extends SwingWorker<String, Void> {
   private File file;

   public OpenFileWorker(File file) {
      this.file = file;
   }

   public File getFile() {
      return file;
   }

   @Override
   protected String doInBackground() throws Exception {
      StringBuilder stringBuilder = new StringBuilder();
      Scanner scan = null;
      try {
         scan = new Scanner(file);
         while (scan.hasNextLine()) {
            stringBuilder.append(scan.nextLine() + "\n");
         }

      } catch (FileNotFoundException e) {
         e.printStackTrace();
      } finally {
         if (scan != null) {
            scan.close();
         }
      }
      return stringBuilder.toString();
   }
}

class OpenFileWorkerListener implements PropertyChangeListener {
   private MvcModel model;

   public OpenFileWorkerListener(MvcModel model) {
      this.model = model;
   }

   @Override
   public void propertyChange(PropertyChangeEvent evt) {
      if (SwingWorker.StateValue.DONE == evt.getNewValue()) {
         OpenFileWorker openFileWorker = (OpenFileWorker) evt.getSource();
         try {
            String text = openFileWorker.get();
            model.setText(text);
            model.setStatus("File \"" + openFileWorker.getFile().getName() + "\" opened");
         } catch (InterruptedException e) {
            e.printStackTrace();
         } catch (ExecutionException e) {
            e.printStackTrace();
         }
      }
   }
}

@SuppressWarnings("serial")
class FileAction extends AbstractAction {
   public FileAction(String name, int keyCode) {
      super(name);
      putValue(MNEMONIC_KEY, keyCode);
   }

   @Override
   public void actionPerformed(ActionEvent arg0) {
      // pretty much empty
   }
}

@SuppressWarnings("serial")
class SaveToFileAction extends AbstractAction {
   private MvcView view;
   private MvcModel model;

   public SaveToFileAction(MvcView view, MvcModel model, String name,
         int keyCode) {
      super(name);
      putValue(MNEMONIC_KEY, keyCode);
      this.view = view;
      this.model = model;
   }

   @Override
   public void actionPerformed(ActionEvent e) {
      // TODO finish!
   }
}

@SuppressWarnings("serial")
class ExitAction extends AbstractAction {
   private MvcView view;
   // private MvcModel model; // TODO: may use this later

   public ExitAction(MvcView view, MvcModel model, String name, int keyCode) {
      super(name);
      putValue(MNEMONIC_KEY, keyCode);
      this.view = view;
      // this.model = model; // TODO: may use this later
   }

   @Override
   public void actionPerformed(ActionEvent e) {
      view.getTopWindow().dispose();
   }
}

class ModelListener implements PropertyChangeListener {
   private MvcView view;
   private MvcModel model;

   public ModelListener(MvcView view, MvcModel model) {
      this.view = view;
      this.model = model;
   }

   @Override
   public void propertyChange(PropertyChangeEvent pcEvt) {
      if (MvcModel.TEXT.equals(pcEvt.getPropertyName())) {
         view.setTextAreaText(model.getText());
      }

      else if (MvcModel.STATUS.equals(pcEvt.getPropertyName())) {
         view.setStatusText(model.getStatus());
      }
   }

}

Java , , . , , "" , Swing . , , , , .

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