Idea -- use @slf4j to print logs

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Preface

In previous project development , Log printing is often an indispensable operation .

before

In previous project development , The following methods should be used to print logs , Create a private class instance in each class .

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

private Logger log = LoggerFactory.getLogger(Test.class);

Then you need to print the location of the log , Adopt the following methods to display the log ：

log.info();
log.warn();
log.debug();
log.error();

But every class needs to actively declare , Is it too much trouble ！

Now?

Now you can take @lombok.extern.slf4j.Slf4j Annotation for simplification , The following are the specific implementation steps ：

• 1、 Introduce dependency
  Because of the use of @Slf4j, This note is also lombok A note in . Just introduce the following dependencies ：

<dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.16.20</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
        <version>1.7.26</version>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-log4j12</artifactId>
        <version>1.7.26</version>
    </dependency>

• 2、 Add log configuration item
  stay resources Add in folder log4j.properties The configuration file , The configuration information is shown below

log4j.rootLogger=debug, stdout, R

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout

log4j.appender.stdout.layout.ConversionPattern=%5p - %m%n

log4j.appender.R=org.apache.log4j.RollingFileAppender
log4j.appender.R.File=firestorm.log

log4j.appender.R.MaxFileSize=100KB
log4j.appender.R.MaxBackupIndex=1

log4j.appender.R.layout=org.apache.log4j.PatternLayout
log4j.appender.R.layout.ConversionPattern=%p %t %c - %m%n

log4j.logger.com.codefutures=DEBUG

• 3、 Use... In classes @Slf4j

The effect after execution is as follows ：

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class Test {
    
    public static void main(String[] args) {
    
      log.info(" Focus on writing bug");
    }
}

IDEA—— Use @Slf4j Print log

IDEA When compiling, report Error: java: Symbol not found : Variable log lombok Failure problem

IDEA When compiling, report Error: java: Symbol not found : Variable log lombok Failure problem