Log tracking and debugging skills based on Apache Log4J API
Log tracking and debugging skills based on Apache Log4J API
Overview:
Log is an important part of software development and errors.It can help developers track the operation of the software, understand the execution of the code, and provide useful information when checking the problem.Apache Log4j is a powerful Java log framework that is widely used in various Java applications.This article will introduce how to use Apache Log4j API to achieve log tracking and debugging, while providing some practical skills and example code.
1. Introduce log4j dependencies:
First, you need to introduce log4j dependencies in the project.You can manage dependence through Maven, add the following code fragment to the pom.xml file of the project:
<dependencies>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-api</artifactId>
<version>2.14.0</version>
</dependency>
</dependencies>
Second, configure log4j attribute file:
Before using LOG4J, you need to create a attribute file called log4j2.xml to configure the format and level information of the log output.The following is a simple example:
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="INFO">
<Appenders>
<Console name="Console" target="SYSTEM_OUT">
<PatternLayout pattern="%d{HH:mm:ss.SSS} [%-5level] %logger{36} - %msg%n" />
</Console>
</Appenders>
<Loggers>
<Root level="debug">
<AppenderRef ref="Console" />
</Root>
</Loggers>
</Configuration>
In the above examples, the APPENDER named Console console is defined, and a logger with a root level of Debug.You can configure it as needed, such as adding a file output APPENDER or modifying the log format.
3. Use log4j in the code:
1. Import LOG4J class library:
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
2. Initialize logger:
private static final Logger logger = LogManager.getLogger(YourClass.class);
In the above code, you need to replace "Yourclass" to the class name of actual use of log4j.
3. Output log information:
Call different levels of log output methods through the logger object, such as:
logger.trace("This is a trace message");
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");
Depending on the log level, the details of the log display can be easily controlled.
Fourth, debug skills and instance code:
1. Use log tracking method:
Use the loger.trace () method in the code to conduct detailed debugging and tracking.When you need to track the execution path of a method or view the value of the variable, you can call the method at the corresponding location and output the relevant information.For example:
public void yourMethod() {
logger.trace("Entering yourMethod");
// code execution path tracking code ...
logger.trace("Exiting yourMethod");
}
By viewing the log output, you can understand the state of each key point in the execution path.
2. Output logs in abnormal treatment:
In the capture abnormal code block, output exception information through the logger.error () method in order to better understand the location and specific cause of the abnormal occurrence.For example:
try {
// The code that may occur ...
} catch (Exception e) {
logger.error("An error occurred: {}", e.getMessage());
}
Output the specific abnormal information into the log to facilitate positioning problems.
in conclusion:
This article introduces how to use Apache Log4j API to achieve log tracking and debugging.By correcting the log4j attribute file and output different levels of log information using the logger object, more useful information can be obtained in the development and error discharge process.In addition, some practical skills and examples are provided to help developers better use log4j for log management.
The relevant code example can be found below:
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
public class Log4jExample {
private static final Logger logger = LogManager.getLogger(Log4jExample.class);
public static void main(String[] args) {
logger.trace("This is a trace message");
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");
}
}
It is hoped that this article can help readers better understand and use log tracking and debugging skills based on Apache Log4J API.
