How to customize logging content in log4j?

To customize the content of Log4j logs, you can utilize the Layout component of Log4j.

1. Create a custom Layout class that inherits from the Log4j Layout interface, eg:

import org.apache.log4j.Layout;
import org.apache.log4j.spi.LoggingEvent;

public class CustomLayout extends Layout {
  
  @Override
  public String format(LoggingEvent event) {
    // 自定义日志格式
    return event.getLevel() + " - " + event.getMessage();
  }

  @Override
  public boolean ignoresThrowable() {
    return false;
  }

  @Override
  public void activateOptions() {
    // 可选的，可以在这里进行一些初始化操作
  }
  
  // 其他自定义方法...
  
}

1. Specify your custom Layout class in the Log4j configuration file (usually log4j.properties or log4j.xml). For example:

# log4j.properties

log4j.appender.myAppender=org.apache.log4j.ConsoleAppender
log4j.appender.myAppender.layout=com.example.CustomLayout

In the above example, a custom Layout class called com.example.CustomLayout is assigned to an Appender named myAppender.

You can customize the content of Log4j logs by following the steps above. You can add formatting logic to customize the content of logs in your own Layout class, such as adding timestamps and thread information according to your needs.