log4j重定向到Swing的JTextArea中

一、前言

一些研发软件会把日志打到界面上，方便工程师调试。 java里我们经常会用log4j来打日志，打到文件里，控制台都是常见操作，那么怎么把它重定向到界面里呢。

二、准备

1.win10

2.eclipse

3.jdk 1.8.0_221

4.jar

log4j：log4j-1.2.17.jar下载链接 实测可用，就是加载网页速度慢了点，为什么慢大家应该也能理解。

commons-logging：commons-logging-1.2.jar下载链接

三、结构

四、代码

1.main启动

package lyrics.main; import java.awt.EventQueue; import lyrics.ui.LogRedirectUI; /** * * @author lyrics * @since 2020/07/01 */ public class Main { public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { new LogRedirectUI(); } catch (Exception e) { e.printStackTrace(); } } }); } }

2.界面LogRedirectUI

package lyrics.ui; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JTextArea; import org.apache.log4j.Logger; import lyrics.logger.TextAreaLogAppender; import javax.swing.JScrollPane; import javax.swing.JButton; /** * * @author lyrics * @since 2020/07/01 */ public class LogRedirectUI { private final static Logger log = Logger.getLogger(LogRedirectUI.class); private JFrame frame; private JScrollPane scrollPane = new JScrollPane(); private JTextArea textArea = new JTextArea(); /** * Create the application. */ public LogRedirectUI() { initialize(); initLog(); } /** * Initialize the contents of the frame. */ private void initialize() { frame = new JFrame(); frame.setVisible(true); frame.setTitle("Log redirect"); frame.setBounds(100, 100, 470, 514); frame.setLocationRelativeTo(null); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().setLayout(null); scrollPane.setBounds(0, 114, 452, 353); frame.getContentPane().add(scrollPane); scrollPane.setViewportView(textArea); JButton btnButton1 = new JButton("button1"); btnButton1.setBounds(28, 53, 113, 27); frame.getContentPane().add(btnButton1); JButton btnButton2 = new JButton("button2"); btnButton2.setBounds(169, 53, 113, 27); frame.getContentPane().add(btnButton2); JButton btnButton3 = new JButton("button3"); btnButton3.setBounds(310, 53, 113, 27); frame.getContentPane().add(btnButton3); // 添加监听 btnButton1.addActionListener(event -> { log.info("button 1 pressed!"); }); btnButton2.addActionListener(event -> { log.info("button 2 pressed!"); }); btnButton3.addActionListener(event -> { log.info("button 3 pressed!"); }); } private void initLog() { try { Thread thread; thread = new TextAreaLogAppender(textArea, scrollPane); thread.start(); } catch (Exception e) { JOptionPane.showMessageDialog(null, "重定向错误"); } } }

3.日志重定向

TextAreaLogAppender

package lyrics.logger; import java.io.IOException; import java.util.Scanner; import javax.swing.JScrollPane; import javax.swing.JTextArea; /** * 重定向 * * * @author lyrics * @since 2020/07/01 */ public class TextAreaLogAppender extends LogAppender { private JTextArea textArea; private JScrollPane scroll; public TextAreaLogAppender(JTextArea textArea, JScrollPane scroll) throws IOException { super("textArea"); this.textArea = textArea; this.scroll = scroll; } @SuppressWarnings("resource") @Override public void run() { Scanner scanner = new Scanner(reader); while (scanner.hasNextLine()) { try { Thread.sleep(100); String line = scanner.nextLine(); textArea.append(line); textArea.append("\n"); line = null; scroll.getVerticalScrollBar().setValue(scroll.getVerticalScrollBar().getMaximum()); } catch (Exception ex) { } } } }

LogAppender

package lyrics.logger; import java.io.IOException; import java.io.PipedReader; import java.io.PipedWriter; import java.io.Writer; import org.apache.log4j.Appender; import org.apache.log4j.Logger; import org.apache.log4j.WriterAppender; /** * * @author lyrics * @since 2020/07/01 */ public abstract class LogAppender extends Thread { protected PipedReader reader; public LogAppender(String appenderName) throws IOException { Logger root = Logger.getRootLogger(); // 获取子记录器的输出源 Appender appender = root.getAppender(appenderName); // 定义一个未连接的输入流管道 reader = new PipedReader(); // 定义一个已连接的输出流管理，并连接到reader Writer writer = new PipedWriter(reader); // 设置 appender 输出流 ((WriterAppender) appender).setWriter(writer); } }

4.log4j.properties文件

log4j.appender.console=org.apache.log4j.ConsoleAppender log4j.appender.console.layout=org.apache.log4j.PatternLayout log4j.appender.console.layout.ConversionPattern=%%-d{yyyy-MM-dd HH:mm:ss} [ %p ] %m%n log4j.appender.textArea=org.apache.log4j.ConsoleAppender log4j.appender.textArea.layout=org.apache.log4j.PatternLayout log4j.appender.textArea.layout.ConversionPattern=%-d{yyyy-MM-dd HH:mm:ss} [ %p ] %m%n log4j.rootLogger=INFO,console,textArea

五、效果

效果图一： 效果图二： 效果图三：

六、最后

本文有些地方参考了网上的资料，有些地方可能会有不足，望诸位海涵！ 晚安！！！ 工程下载链接：https://download.csdn.net/download/LyRics1996/12568246