编辑:我编辑了帖子以澄清我的问题,现在我自己也有了更多的理解。
正如标题所说,我本质上是在我的GUI中尝试将控制台输出到我的JTextArea
,同时执行应用程序的任务。
以下是我目前正在做的事情:
public class TextAreaOutputStream extends OutputStream
{
private final JTextArea textArea;
private final StringBuilder sb = new StringBuilder();
public TextAreaOutputStream(final JTextArea textArea)
{
this.textArea = textArea;
}
@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((char) b);
}
}
以上内容会成功将System.out
重定向到上面的输出流,因此会向EventQueue
发送一个事件来更新我的GUI(JTextArea
)。
问题在于:
目前正在使用invokeLater()
,如文档中所述:
Causes runnable to have its run method called in the dispatch thread of the EventQueue. This will happen after all pending events are processed.
所以我真正想要做的是在处理EventQueue中的所有其他内容之前执行对GUI的更新(调用run()
)。
是否可以将事件注入我的EventQueue?或者有人可以指点我在这方面的一个体面的教程吗?
感谢,
答案 0 :(得分:10)
以下示例使用文本区域创建框架并将System.out重定向到它:
import java.awt.BorderLayout;
import java.awt.Container;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
public class JTextAreaOutputStream extends OutputStream
{
private final JTextArea destination;
public JTextAreaOutputStream (JTextArea destination)
{
if (destination == null)
throw new IllegalArgumentException ("Destination is null");
this.destination = destination;
}
@Override
public void write(byte[] buffer, int offset, int length) throws IOException
{
final String text = new String (buffer, offset, length);
SwingUtilities.invokeLater(new Runnable ()
{
@Override
public void run()
{
destination.append (text);
}
});
}
@Override
public void write(int b) throws IOException
{
write (new byte [] {(byte)b}, 0, 1);
}
public static void main (String[] args) throws Exception
{
JTextArea textArea = new JTextArea (25, 80);
textArea.setEditable (false);
JFrame frame = new JFrame ("stdout");
frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
Container contentPane = frame.getContentPane ();
contentPane.setLayout (new BorderLayout ());
contentPane.add (
new JScrollPane (
textArea,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED),
BorderLayout.CENTER);
frame.pack ();
frame.setVisible (true);
JTextAreaOutputStream out = new JTextAreaOutputStream (textArea);
System.setOut (new PrintStream (out));
while (true)
{
System.out.println ("Current time: " + System.currentTimeMillis ());
Thread.sleep (1000L);
}
}
}
答案 1 :(得分:4)
您的错误必须位于您尚未向我们展示的其他地方。这是一个非常简单的演示,按预期工作,与您的代码几乎相同(我只修复了一些小问题):
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
public class TextAreaOutputStream extends OutputStream {
private final JTextArea textArea;
private final StringBuilder sb = new StringBuilder();
public TextAreaOutputStream(final JTextArea textArea) {
this.textArea = textArea;
}
@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";
textArea.append(text);
sb.setLength(0);
} else {
sb.append((char) b);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
JFrame frame = new JFrame(TextAreaOutputStream.class.getSimpleName());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextArea ta = new JTextArea(24, 80);
System.setOut(new PrintStream(new TextAreaOutputStream(ta)));
frame.add(new JScrollPane(ta));
frame.pack();
frame.setVisible(true);
System.out.println("Textarea console initiated");
Timer t = new Timer(1000, new ActionListener() {
int count = 1;
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("Outputting line " + count++ + " to the console. Working properly, no?");
}
});
t.start();
}
});
}
}
答案 2 :(得分:2)
您可能需要使用PipedOutputStream
...请在此处查看问题的答案:
How to redirect all console output to a Swing JTextArea/JTextPane with the right encoding?
基本上它的作用是,它将System.out
重定向到一个缓冲区,程序可以从中读取用System.out
打印的输出。这称为Piping
答案 3 :(得分:0)
如果要在文本区域中查看滚动效果,则可以将新文本放在开头,而不是附加输出。 例如:
HttpURLConnection con = (HttpURLConnection) (new URL(url[0]).openConnection());
con.setInstanceFollowRedirects(false);
con.connect();
int responseCode = con.getResponseCode();
String location = con.getHeaderField("Location");
textArea.setText(url[0] +"," +responseCode+"," +location+"\n"+textArea.getText()); //new text is prefixed to the existing text
textArea.update(textArea.getGraphics());
答案 4 :(得分:0)
我发现了一个非常简单的,虽然可能不是最快或最好的方法。然而,它非常简单,如果你像我一样懒惰,那么它的效果很好。
JTextArea output = new JTextArea();
PrintStream out = new PrintStream(new OutputStream() {
@Override
public void write(int b) throws IOException {
output.append(""+(char)(b & 0xFF));
}
});
System.setOut(out);
System.out.println("TEST");