corejava第10版

corejava第10版/v2ch10/progressMonitorInputStream/ProgressMonitorInputStreamTest.java

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+package progressMonitorInputStream;
+
+import java.awt.*;
+import javax.swing.*;
+
+/**
+ * A program to test a progress monitor input stream.
+ * @version 1.06 2016-05-10
+ * @author Cay Horstmann
+ */
+public class ProgressMonitorInputStreamTest
+{
+   public static void main(String[] args)
+   {
+      EventQueue.invokeLater(() ->
+         {
+            JFrame frame = new TextFrame();
+            frame.setTitle("ProgressMonitorInputStreamTest");
+            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+            frame.setVisible(true);
+         });
+   }
+}

corejava第10版/v2ch10/progressMonitorInputStream/TextFrame.java

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+package progressMonitorInputStream;
+
+import java.io.*;
+import java.nio.file.*;
+import java.util.*;
+
+import javax.swing.*;
+
+/**
+ * A frame with a menu to load a text file and a text area to display its contents. The text area is
+ * constructed when the file is loaded and set as the content pane of the frame when the loading is
+ * complete. That avoids flicker during loading.
+ */
+public class TextFrame extends JFrame
+{
+   public static final int TEXT_ROWS = 10;
+   public static final int TEXT_COLUMNS = 40;
+
+   private JMenuItem openItem;
+   private JMenuItem exitItem;
+   private JTextArea textArea;
+   private JFileChooser chooser;
+
+   public TextFrame()
+   {
+      textArea = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
+      add(new JScrollPane(textArea));
+
+      chooser = new JFileChooser();
+      chooser.setCurrentDirectory(new File("."));
+
+      JMenuBar menuBar = new JMenuBar();
+      setJMenuBar(menuBar);
+      JMenu fileMenu = new JMenu("File");
+      menuBar.add(fileMenu);
+      openItem = new JMenuItem("Open");
+      openItem.addActionListener(event ->
+         {
+            try
+            {
+               openFile();
+            }
+            catch (IOException exception)
+            {
+               exception.printStackTrace();
+            }
+         });
+
+      fileMenu.add(openItem);
+      exitItem = new JMenuItem("Exit");
+      exitItem.addActionListener(event -> System.exit(0));
+      fileMenu.add(exitItem);
+      pack();
+   }
+
+   /**
+    * Prompts the user to select a file, loads the file into a text area, and sets it as the content
+    * pane of the frame.
+    */
+   public void openFile() throws IOException
+   {
+      int r = chooser.showOpenDialog(this);
+      if (r != JFileChooser.APPROVE_OPTION) return;
+      final File f = chooser.getSelectedFile();
+
+      // set up stream and reader filter sequence
+      
+      InputStream fileIn = Files.newInputStream(f.toPath());
+      final ProgressMonitorInputStream progressIn = new ProgressMonitorInputStream(
+         this, "Reading " + f.getName(), fileIn);      
+
+      textArea.setText("");
+
+      SwingWorker<Void, Void> worker = new SwingWorker<Void, Void>()
+         {
+            protected Void doInBackground() throws Exception
+            {
+               try (Scanner in = new Scanner(progressIn, "UTF-8"))
+               {
+                  while (in.hasNextLine())
+                  {
+                     String line = in.nextLine();
+                     textArea.append(line);
+                     textArea.append("\n");
+                  }
+               }
+               return null;
+            }
+         };
+      worker.execute();
+   }
+}