java - 如何在 JFrame/JPanel 中可视化控制台 java

Question

我使用 Swing 库制作了一个 Java 程序。现在我想将我的控制台输出重定向到 JFrame 或 JPanel。

Answer 1

您需要创建一个将输出重定向到文本区域并实现 OutputStream 接口的所有必要方法的 OutputStream，然后在您的主程序中，将您的标准输出重定向到此流中。我在我的一个程序中使用了这样的东西：

import java.io.IOException;
import java.io.OutputStream;

import javax.swing.JTextArea;
import javax.swing.SwingUtilities;

public class TextAreaOutputStream extends OutputStream {

   private final JTextArea textArea;
   private final StringBuilder sb = new StringBuilder();
   private String title;

   public TextAreaOutputStream(final JTextArea textArea, String title) {
      this.textArea = textArea;
      this.title = title;
      sb.append(title + "> ");
   }

   @Override
   public void flush() {
   }

   @Override
   public void close() {
   }

   @Override
   public void write(int b) throws IOException {

      if (b == '\r')
         return;

      if (b == '\n') {
         final String text = sb.toString() + "\n";
         SwingUtilities.invokeLater(new Runnable() {
            public void run() {
               textArea.append(text);
            }
         });
         sb.setLength(0);
         sb.append(title + "> ");
         return;
      }

      sb.append((char) b);
   }
}

你可以用这个来证明它：

import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.PrintStream;
import javax.swing.*;

@SuppressWarnings("serial")
public class TextAreaOutputStreamTest extends JPanel {

   private JTextArea textArea = new JTextArea(15, 30);
   private TextAreaOutputStream taOutputStream = new TextAreaOutputStream(
         textArea, "Test");

   public TextAreaOutputStreamTest() {
      setLayout(new BorderLayout());
      add(new JScrollPane(textArea, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, 
            JScrollPane.HORIZONTAL_SCROLLBAR_NEVER));
      System.setOut(new PrintStream(taOutputStream));

      int timerDelay = 1000;
      new Timer(timerDelay , new ActionListener() {
         int count = 0;
         @Override
         public void actionPerformed(ActionEvent arg0) {

            // though this outputs via System.out.println, it actually displays
            // in the JTextArea:
            System.out.println("Count is now: " + count + " seconds");
            count++;
         }
      }).start();
   }

   private static void createAndShowGui() {
      JFrame frame = new JFrame("Test");
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.getContentPane().add(new TextAreaOutputStreamTest());
      frame.pack();
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
   }

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

Answer 2

拥有JFrameorJPanel后，向其中添加一个文本字段。

JTextArea是一个不错的选择，因为它是多行。添加后，您可以添加.append('text');它而不是编写System.out.print();

JFrame jFrame = new JFrame();

JTextArea jTextArea = new JTextArea();
jTextArea.append( "Hello World." );

jFrame.add( jTextArea );

Answer 3

我知道我迟到了，但是对于正在寻找更好、更紧凑的答案的人，我让这个女巫结合了两个自定义类。

控制台.java

public class Console {
    final JFrame frame = new JFrame("CONSOLE");
    ColorPane textPane;
    JScrollPane scroll;

    public Console() throws Exception {
        textPane = new ColorPane();
        textPane.setPreferredSize(new Dimension(525, 600));
        textPane.setFont(new Font("Lucida Console", Font.BOLD, 12));
        scroll = new JScrollPane(textPane);
        textPane.setBackground(Color.BLACK);

        scroll.setVerticalScrollBarPolicy ( ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS );

        textPane.getDocument().addDocumentListener(new DocumentListener() {
            @Override
            public void insertUpdate(DocumentEvent e) {
                scrollToBottom(scroll);
            }

            @Override
            public void removeUpdate(DocumentEvent e) {

            }

            @Override
            public void changedUpdate(DocumentEvent e) {

            }
        });

        //Add textPane in to middle panel
        frame.add(scroll);
        frame.setSize(100, 600);
        frame.pack();
        frame.setVisible(false);
        redirectOut();

    }

    public PrintStream redirectOut() {
        OutputStream out = new OutputStream() {
            @Override
            public void write(int b) throws IOException {
                textPane.append(Color.WHITE, String.valueOf((char) b));
            }
        };
        OutputStream errOut = new OutputStream() {
            @Override
            public void write(int b) throws IOException {
                textPane.append(Color.RED, String.valueOf((char) b));
            }
        };
        PrintStream ps = new PrintStream(out);
        PrintStream err = new PrintStream(errOut);

        System.setOut(ps);
        System.setErr(err);
        scrollToBottom(scroll);

        return ps;
    }

    public JFrame getFrame() {
        return frame;
    }

    private void scrollToBottom(JScrollPane scrollPane) {
        JScrollBar verticalBar = scrollPane.getVerticalScrollBar();
        AdjustmentListener downScroller = new AdjustmentListener() {
            @Override
            public void adjustmentValueChanged(AdjustmentEvent e) {
                Adjustable adjustable = e.getAdjustable();
                adjustable.setValue(adjustable.getMaximum());
                verticalBar.removeAdjustmentListener(this);
            }
        };
        verticalBar.addAdjustmentListener(downScroller);
    }
}

和 ColorPane.java

import java.awt.Color;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextPane;
import javax.swing.text.AttributeSet;
import javax.swing.text.SimpleAttributeSet;
import javax.swing.text.StyleConstants;
import javax.swing.text.StyleContext;

public class ColorPane extends JTextPane {

    public void appendNaive(Color c, String s) { // naive implementation
        // bad: instiantiates a new AttributeSet object on each call
        SimpleAttributeSet aset = new SimpleAttributeSet();
        StyleConstants.setForeground(aset, c);

        int len = getText().length();
        setCaretPosition(len); // place caret at the end (with no selection)
        setCharacterAttributes(aset, false);
        replaceSelection(s); // there is no selection, so inserts at caret
    }

    public void append(Color c, String s) { // better implementation--uses
        // StyleContext
        StyleContext sc = StyleContext.getDefaultStyleContext();
        AttributeSet aset = sc.addAttribute(SimpleAttributeSet.EMPTY,
                StyleConstants.Foreground, c);

        int len = getDocument().getLength(); // same value as
        // getText().length();
        setCaretPosition(len); // place caret at the end (with no selection)
        setCharacterAttributes(aset, false);
        replaceSelection(s); // there is no selection, so inserts at caret
    }

    public static boolean isPrime(int n) {
        if (n < 2)
            return false;
        double max = Math.sqrt(n);
        for (int j = 2; j <= max; j += 1)
            if (n % j == 0)
                return false; // j is a factor
        return true;
    }

    public static boolean isPerfectSquare(int n) {
        int j = 1;
        while (j * j < n && j * j > 0)
            j += 1;
        return (j * j == n);
    }

}

这是我一直在使用的解决方案，它甚至有彩色输出。PS：顺便说一句，英语不好（我只有 11 岁）