corejava第10版

corejava第10版/v1ch02/ImageViewer/ImageViewer.java

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+import java.awt.*;
+import java.io.*;
+import javax.swing.*;
+
+/**
+ * A program for viewing images.
+ * @version 1.30 2014-02-27
+ * @author Cay Horstmann
+ */
+public class ImageViewer
+{
+   public static void main(String[] args)
+   {
+      EventQueue.invokeLater(() -> {
+         JFrame frame = new ImageViewerFrame();
+         frame.setTitle("ImageViewer");
+         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+         frame.setVisible(true);
+      });
+   }
+}
+
+/**
+ * A frame with a label to show an image.
+ */
+class ImageViewerFrame extends JFrame
+{
+   private JLabel label;
+   private JFileChooser chooser;
+   private static final int DEFAULT_WIDTH = 300;
+   private static final int DEFAULT_HEIGHT = 400;
+
+   public ImageViewerFrame()
+   {
+      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
+
+      // use a label to display the images
+      label = new JLabel();
+      add(label);
+
+      // set up the file chooser
+      chooser = new JFileChooser();
+      chooser.setCurrentDirectory(new File("."));
+
+      // set up the menu bar
+      JMenuBar menuBar = new JMenuBar();
+      setJMenuBar(menuBar);
+
+      JMenu menu = new JMenu("File");
+      menuBar.add(menu);
+
+      JMenuItem openItem = new JMenuItem("Open");
+      menu.add(openItem);
+      openItem.addActionListener(event -> {
+         // show file chooser dialog
+            int result = chooser.showOpenDialog(null);
+
+            // if file selected, set it as icon of the label
+            if (result == JFileChooser.APPROVE_OPTION)
+            {
+               String name = chooser.getSelectedFile().getPath();
+               label.setIcon(new ImageIcon(name));
+            }
+         });
+
+      JMenuItem exitItem = new JMenuItem("Exit");
+      menu.add(exitItem);
+      exitItem.addActionListener(event -> System.exit(0));
+   }
+}