Common logging problems and solutions in Java development

Common logging problems and solutions in Java development, specific code examples are required

In Java development, logging is a very important part. It can help us track problems, troubleshoot errors while the program is running, and help us analyze the performance of the program. However, in actual development, we may encounter some logging problems. This article will introduce some common problems and provide solutions and sample code.

Problem 1: Incomplete log output or missing part of the log

When the program runs for a period of time, we may find that part of the log is not output, or only part of the log is output. This may be because the logger uses a buffer before writing the logs to disk. If the appropriate flush mechanism is not called, the logs in the buffer may not be output.

The solution is as follows:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LogExample {
    private static final Logger LOGGER = LoggerFactory.getLogger(LogExample.class);

    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            LOGGER.info("This is an example log message. Number: {}", i);
            LOGGER.flush(); // 刷新日志
        }
    }
}

Problem 2: The log output is too lengthy

Sometimes, we may only care about certain specific logs and do not want to output all logs. To solve this problem, we can filter the logs by setting the log level.

The solution is as follows:

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LogExample {
    private static final Logger LOGGER = LoggerFactory.getLogger(LogExample.class);

    public static void main(String[] args) {
        LOGGER.info("This is an informational message."); // 输出普通信息
        LOGGER.debug("This is a debugging message."); // 输出调试信息
        LOGGER.warn("This is a warning message."); // 输出警告信息
        LOGGER.error("This is an error message."); // 输出错误信息
    }
}

Problem 3: Logger configuration error

When using the logger, we need to configure the corresponding logger implementation. If the configuration is incorrect, the log may not be output or the output may not meet expectations.

The solution is as follows:
In the resource directory of the project, create a file named log4j2.xml and add the following content:

<?xml version="1.0" encoding="UTF-8"?>
<configuration status="INFO">
    <appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"/>
        </Console>
    </appenders>
    <loggers>
        <root level="info">
            <appender-ref ref="Console"/>
        </root>
    </loggers>
</configuration>

Then, Place this file in the project's Classpath.

Problem 4: Loggers under different packages cannot output logs

In Java, loggers are identified based on the fully qualified name of the class. Therefore, if the same class name is used in different packages, the logger may not be able to output logs.

The solution is as follows:
When using the logger, you can use the fully qualified name of the class to obtain the logger instance to avoid class name conflicts.

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class LogExample {
    private static final Logger LOGGER = LoggerFactory.getLogger(LogExample.class);

    public static void main(String[] args) {
        LOGGER.info("This is an example log message.");
    }
}

Summary:

In Java development, logging is very important. By solving common logging issues, we can make better use of logging to troubleshoot problems and optimize program performance. This article introduces common problems such as incomplete log output or missing part of the log, too lengthy log output, incorrect configuration of the logger, and failure of loggers under different packages to output logs. It also provides corresponding solutions and sample codes. I hope It can help developers better handle various issues related to logging.

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