How to use Apache log4j API to implement log -level management

How to use Apache log4j API to implement log -level management Apache Log4j is a powerful log record framework that helps us to achieve efficient log management.One of the important functions is to control the output of log information at different levels by setting the log level.This article will introduce how to use Apache log4j API to implement log -level management and provide corresponding Java code examples. First of all, we need to ensure that the Apache Log4j library has been added to the dependence of the project. Next, create a configuration file called log4j.properties to configure log4j log level and output methods.The content of the configuration file is as follows: properties # Set the log level of the root logger as Debug log4j.rootLogger=DEBUG, stdout # Output to the console log4j.appender.stdout=org.apache.log4j.ConsoleAppender log4j.appender.stdout.layout=org.apache.log4j.PatternLayout log4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} [%-5p] %c{1} - %m%n # Set the log level of a specific package is info log4j.logger.com.example=INFO In the above configuration, we set the ROOT LOGER log level to Debug, which means that all levels of log information will be output.At the same time, we set up a ConsoleAppender to output log information to the console.The time, log level, class name and log message of each log will be displayed on the screen. In addition, we have specially set up the log level of the COM.EXAMPLE package as INFO.This means that only the INFO level and above logo will be output. Next, we use the log4j API in the Java code to record the log.Suppose we have a class called MyClass, the code is as follows: import org.apache.log4j.Logger; public class MyClass { private static final Logger logger = Logger.getLogger(MyClass.class); public static void main(String[] args) { logger.debug("This is a debug message"); logger.info("This is an info message"); logger.warn("This is a warning message"); logger.error("This is an error message"); logger.fatal("This is a fatal message"); } } In the above code, we first obtain a Logger instance through the logger.getLogger method, and the parameter is introduced into MyClass.Class to represent the current class.We then use different levels of logs to record different levels of log information. When we run this code, the console will output the following: 2022-01-01 12:00:00 [DEBUG] com.example.MyClass - This is a debug message 2022-01-01 12:00:01 [INFO ] com.example.MyClass - This is an info message 2022-01-01 12:00:02 [WARN ] com.example.MyClass - This is a warning message 2022-01-01 12:00:03 [ERROR] com.example.MyClass - This is an error message 2022-01-01 12:00:04 [FATAL] com.example.MyClass - This is a fatal message It can be seen that all levels of log information output to the console according to the format defined in the configuration file. According to the settings in the configuration file, the debug -level log information of the com.example package will also be output.If we modify the COM.EXAMPLE level in the configuration file, the level is Warn, and the code is reopened, you will find that only the log information of Warn, ERROR and FATAL levels is output. In this way, we can easily control the output of log information at different levels.By adjusting the log level in the configuration file, we can flexibly control the details of the log without modifying the code. Summarize: This article introduces how to use Apache Log4j API to implement log -level management.We first created a configuration file log4j.properties, and set up the log level of the root logger as Debug, the output method as the console, and specially set the log level of the com.example package.Then, we used the log4j API to record the log information of different levels in the code, and control the output of the log information of different levels according to the settings in the configuration file. I hope that through the introduction of this article, you can have a better understanding of how to use APACHE LOG4J API to implement log -level management.