之前发的小控件有点问题，不换行就不会提交更改，修改代码如下：
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.Timer;public class JOutputPane extends JTextArea {private OutputStream out = this.new PaneOutputStream();private Color candy = new Color(240, 240, 255);@Overridepublic boolean isOpaque() {return false;}public OutputStream getOutputStream() {return out;}@Overrideprotected void paintComponent(Graphics g) {int width = getWidth();int height = getHeight();Color old = g.getColor();g.setColor(getBackground());g.fillRect(0, 0, width, height);Rectangle r = new Rectangle();r.x = 0;r.y = 0;r.width = width;r.height = getRowHeight();g.setColor(candy);for (int heightIncrement = 2 * getRowHeight();r.y < height;r.y += heightIncrement) {g.fillRect(r.x, r.y, r.width, r.height);}g.setColor(old);super.paintComponent(g);}private class PaneOutputStream extends OutputStream {private final ByteArrayOutputStream buffer = new ByteArrayOutputStream();private final Timer timer;private PaneOutputStream() {timer = new Timer(50, new ActionListener() {@Overridepublic void actionPerformed(ActionEvent e) {commit();}});}@Overridepublic void write(int b) throws IOException {buffer.write(b);timer.restart();}private void commit() {assert SwingUtilities.isEventDispatchThread();timer.stop();if( buffer.size() > 0 ) {append(buffer.toString());buffer.reset();}}}
}
设计上模仿了 JViewPort 对频繁的 scroll 动作的响应方式，用了一个内部的 timer 来控制更新。
需要特别说明的是，对返回的 OutputStream 的任何输出都应该在 EDT 内进行。