Java swing console

最新推荐文章于 2025-06-02 23:23:13 发布

翻译最新推荐文章于 2025-06-02 23:23:13 发布 · 1.6k 阅读

文章标签：

#swing #java #import #character #byte #class

本文介绍了一种在Java中将System.out和System.err重定向到GUI文本区域的方法，通过创建自定义的Console类实现，该类使用PipedInputStream和PipedOutputStream来捕获标准输出和错误输出。

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.text.*;

public class Console extends JFrame {
    PipedInputStream piOut;
    PipedInputStream piErr;
    PipedOutputStream poOut;
    PipedOutputStream poErr;
    JTextArea textArea = new JTextArea();

    public Console() throws IOException {
        // Set up System.out
        piOut = new PipedInputStream();
        poOut = new PipedOutputStream(piOut);
        System.setOut(new PrintStream(poOut, true));

        // Set up System.err
        piErr = new PipedInputStream();
        poErr = new PipedOutputStream(piErr);
        System.setErr(new PrintStream(poErr, true));

        // Add a scrolling text area
        textArea.setEditable(false);
        textArea.setRows(20);
        textArea.setColumns(50);
        getContentPane().add(new JScrollPane(textArea), BorderLayout.CENTER);
        pack();
        setVisible(true);

        // Create reader threads
        new ReaderThread(piOut).start();
        new ReaderThread(piErr).start();
    }

    class ReaderThread extends Thread {
        PipedInputStream pi;

        ReaderThread(PipedInputStream pi) {
            this.pi = pi;
        }

        public void run() {
            final byte[] buf = new byte[1024];
            try {
                while (true) {
                    final int len = pi.read(buf);
                    if (len == -1) {
                        break;
                    }
                    SwingUtilities.invokeLater(new Runnable() {
                        public void run() {
                            textArea.append(new String(buf, 0, len));

                            // Make sure the last line is always visible
                            textArea.setCaretPosition(textArea.getDocument().getLength());

                            // Keep the text area down to a certain character size
                            int idealSize = 1000;
                            int maxExcess = 500;
                            int excess = textArea.getDocument().getLength() - idealSize;
                            if (excess >= maxExcess) {
                                textArea.replaceRange("", 0, excess);
                            }
                        }
                    });
                }
            } catch (IOException e) {
            }
        }
    }
}

The console window is created using

try {
    new Console();
} catch (IOException e) {
}