读取一个日志文件并将其显示在jTextArea中 [英] reading a log file and displaying it in jTextArea

问题描述

我试图读取一个动态更改的文件，并在jTextArea中显示其内容。
我正在使用缓冲读取器进行读取。

我试图在控制台上显示内容，它工作正常，但不能用于jTextArea。 / p>

我正在做类似于

  while（true）
 {
 line = br.readLine（）; 
 if（line == null）
 Thread.sleep（）; 
 else 
 System.out.println（line）; 
 
  

任何帮助将不胜感激。谢谢

解决方案

不要使用 Thread.sleep（）将阻止美国东部时间。如果您想动画结果，请使用 javax.swing.Timer 。只读每一个计时器的迭代，直到它到达文件的结尾，然后停止计时器

  timer = new （100，new ActionListener（）{
 public void actionPerformed（ActionEvent e）{
 String line; 
 if（（line = reader.readLine（））！ = null）{
 textArea.append（line +\\\
）; 
} else {
（（Timer）e.getSource（））。stop（）; $ b $ （b）
} catch（IOException ex）{
 Logger.getLogger（ReadFile.class.getName（））.log（Level.SEVERE，null，ex）; 
} 
 } 
}）; 
  

测试这个程序。我认为它的工作方式是你想要的。

  import java.awt.BorderLayout; 
 import java.awt.event.ActionEvent; 
 import java.awt.event.ActionListener; 
 import java.io.BufferedReader; 
 import java.io.File; 
 import java.io.FileNotFoundException; 
 import java.io.FileReader; 
 import java.io.IOException; 
 import java.util.logging.Level; 
 import java.util.logging.Logger; 
 import javax.swing.JButton; 
 import javax.swing.JFileChooser; 
 import javax.swing.JFrame; 
 import javax.swing.JLabel; 
 import javax.swing.JPanel; 
 import javax.swing.JScrollPane; 
 import javax.swing.JTextArea; 
 import javax.swing.JTextField; 
导入javax.swing.SwingUtilities; 
 import javax.swing.Timer; 
 
 public class ReadFile {
 
 File file = null; 
 BufferedReader reader = null; 
 
定时器定时器=空; 
 private JTextArea textArea; 
 private JTextField jtfFile; 
 private String fileName; 
私人JButton浏览; 
私有JFrame框架; 
 
 public ReadFile（）{
 textArea = new JTextArea（25，60）; 
 frame = new JFrame（Show Log）; 
 
 browse = new JButton（Browse）; 
 browse.addActionListener（new ShowLogListener（））; 
 
 jtfFile = new JTextField（25）; 
 jtfFile.addActionListener（new ShowLogListener（））; 
 $ b $ timer = new Timer（100，new ActionListener（）{
 public void actionPerformed（ActionEvent e）{
 String line; 
 try {
 if （（line = reader.readLine（））！= null）{
 textArea.append（line +\\\
）; 
} else {
（（Timer）e.getSource （））。stop（）; 
} 
} catch（IOException ex）{
 Logger.getLogger（ReadFile.class.getName（））.log（Level.SEVERE，null，ex ）; 
} 
} 
}）; 
 
 JPanel panel = new JPanel（）; 
 panel.add（new JLabel（File：））; 
 panel.add（jtfFile）; 
 panel.add（浏览）; 
 
 frame.add（panel，BorderLayout.NORTH）; 
 frame.add（new JScrollPane（textArea），BorderLayout.CENTER）; 
 frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）; 
 frame.pack（）; 
 frame.setLocationByPlatform（true）; 
 frame.setVisible（true）; 
 
 
 private class ShowLogListener实现ActionListener {
 $ b $ @Override 
 public void actionPerformed（ActionEvent e）{
 JFileChooser chooser = new JFileChooser （）; 
 int result = chooser.showOpenDialog（frame）; 
 if（result == JFileChooser.APPROVE_OPTION）{
 file = chooser.getSelectedFile（）; 
 fileName = file.getName（）; 
 jtfFile.setText（fileName）; 
尝试{
 reader = new BufferedReader（new FileReader（file））; 
} catch（FileNotFoundException ex）{
 Logger.getLogger（ReadFile.class.getName（））.log（Level.SEVERE，null，ex）; 
} 
 timer.start（）; 
 
 
 
 $ b public static void main（String [] args）{
 SwingUtilities.invokeLater（new Runnable（）{
 public void run（）{
 new ReadFile（）; 
} 
}）; 
 
 
 
 
 
  
 
I am trying to read a file that changes dynamically and display its contents in jTextArea.
I am using buffered reader for reading.

I have tried to display the contents on console and it works fine, but doesn't work with jTextArea.

I am doing something like
while(true)
{
  line = br.readLine();
  if(line == null)
    Thread.sleep();
  else
    System.out.println(line);
}
Any help would be appreciated. Thanks
解决方案
Don't use Thread.sleep(), you will block the EDT. Instead use a javax.swing.Timer if you want to "animate" the results. Just read each line each iteration of the timer, until it reaches the end of the file, then stop the timer
timer = new Timer(100, new ActionListener() {
     public void actionPerformed(ActionEvent e) {
          String line;
           try {
                if ((line = reader.readLine()) != null) {
                    textArea.append(line + "\n");
                } else {
                   ((Timer) e.getSource()).stop();
                }
           } catch (IOException ex) {
                Logger.getLogger(ReadFile.class.getName()).log(Level.SEVERE, null, ex);
           }
     }
});
Test this program out. I think it works the way you want it to.
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class ReadFile {

    File file = null;
    BufferedReader reader = null;

    private Timer timer = null;
    private JTextArea textArea;
    private JTextField jtfFile;
    private String fileName;
    private JButton browse;
    private JFrame frame;

    public ReadFile() {
        textArea = new JTextArea(25, 60);
        frame = new JFrame("Show Log");

        browse = new JButton("Browse");
        browse.addActionListener(new ShowLogListener());

        jtfFile = new JTextField(25);
        jtfFile.addActionListener(new ShowLogListener());

        timer = new Timer(100, new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                String line;
                try {
                    if ((line = reader.readLine()) != null) {
                        textArea.append(line + "\n");
                    } else {
                        ((Timer) e.getSource()).stop();
                    }
                } catch (IOException ex) {
                    Logger.getLogger(ReadFile.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
        });

        JPanel panel = new JPanel();
        panel.add(new JLabel("File: "));
        panel.add(jtfFile);
        panel.add(browse);

        frame.add(panel, BorderLayout.NORTH);
        frame.add(new JScrollPane(textArea), BorderLayout.CENTER);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    private class ShowLogListener implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            JFileChooser chooser = new JFileChooser();
            int result = chooser.showOpenDialog(frame);
            if (result == JFileChooser.APPROVE_OPTION) {
                file = chooser.getSelectedFile();
                fileName = file.getName();
                jtfFile.setText(fileName);
                try {
                    reader = new BufferedReader(new FileReader(file));
                } catch (FileNotFoundException ex) {
                    Logger.getLogger(ReadFile.class.getName()).log(Level.SEVERE, null, ex);
                }
                timer.start();
            }
        }
    }

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


                        
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