流程完成后，流程输出才可用 [英] Process output only becomes available after the process has finished

问题描述

我有一个Runnable，它从外部调用的exe(请参见下文)读取控制台输出，并将其写入日志文件和JTextArea.

I have a Runnable that reads Console output from an externally called exe (see below) and writes it to both a log file and a JTextArea.

但是直到exe完全完成，我的Runnable才在JTextArea中不显示控制台输出.如何获取它以在发生时打印控制台输出?

But my Runnable doesn't show the Console output in the JTextArea until the exe completely finishes. How do I get it to print Console output as it happens?

下面的简短代码示例

//主

import java.awt.*;
import java.io.IOException;
import javax.swing.*;

public class Example extends JFrame {

    private static final long serialVersionUID = 1L; 

    public static int maxX, maxY;

    public static JTextArea ta = new JTextArea(20, 60);//For LOG display window

    public static void main(String args[] ) throws IOException
    {   
        new Example();
    }

    public Example() {

        this.setTitle("Example");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //MAIN Panel
        final JPanel main = new JPanel();

        JButton RunButton = button.run(main);
        main.add(RunButton);

        Container container = getContentPane();


        container.add(main);
        this.pack();
        this.setVisible(true);
    }


}

//按钮动作监听器

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.*;


public class button {

    public static JButton run( final JPanel parent ) {
        JButton RunButton = new JButton();      
        RunButton.setText("Start!");

        RunButton.addActionListener(
        new ActionListener()
        {
            public void actionPerformed( ActionEvent event)
            {
                try
                {

                    //Set up LOG Display    
                    JDialog dialog = new JDialog((JFrame)null, "Working...");
                    JPanel temp_panel = new JPanel();
                    temp_panel.add(new JScrollPane(Example.ta));
                    dialog.getContentPane().add(temp_panel);
                    dialog.pack();
                    dialog.setVisible(true);

                    //Build the Command
                    ArrayList<String> command = new ArrayList<String>();
                    command.add("ping");
                    command.add("127.0.0.1");

                    //Start the process
                    Process p = new ProcessBuilder(command).start();

                    //Starts LOG display capture in separate thread 
                    SwingUtilities.invokeLater(new execute(p));

                    //Wait for call to complete
                    p.waitFor();
                }
                catch(Exception err)
                {
                    JOptionPane.showMessageDialog( parent, "Error Executing Run!", "Warning", JOptionPane.ERROR_MESSAGE );  
                }

            }//end ActionPerformed
        });
        return RunButton;
    }
}

//可运行

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class execute implements Runnable {  
    String line;
    Process p; 

    public execute ( Process process ) {
        p = process;
    }

    public void run() {
        try {
            //Read Process Stream Output and write to LOG file
            BufferedReader is = new BufferedReader( new InputStreamReader(p.getInputStream()));

            while ( (line = is.readLine()) != null ) {
                Example.ta.append(line + "\n");
            }   
            System.out.flush();     
        } catch(Exception ex) { ex.printStackTrace(); }  

    }
}

推荐答案

问题不是线程没有捕获数据，而是JTextArea没刷新. repaint()， revalidate()和 updateUI()不会刷新JTextArea，但以下内容可以刷新:

The problem was not that the thread wasn't capturing the data, it was the JTextArea just not refreshing. repaint(), revalidate(), and updateUI() did not refresh the JTextArea, but the following did:

Example.ta.update(Example.ta.getGraphics()); 

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