如何在 Spring Boot Web 应用程序中打印到控制台

Question

Coming from a Node background, what is the equivalent of console.log() in spring boot?

For example I'd like to see in my console the job info in the following method.

@RequestMapping(value = "jobposts/create", method = RequestMethod.POST)
public Job create(@RequestBody Job job){
    System.out.println(job);
    return jobRepository.saveAndFlush(job);
}

System.out.println(); is how I know to do it in Java but it doesn't seem to appear in my console. Using IntelliJ.

Answer 1

System.out.println(job); like you have done.

It prints something like yourpackage.Job@2g45e0f9

Try to execute you code using debug mode and see if the post method will be executed as it has to do.

Answer 2

Did you tried adding console appender in you logging configuration file.? Here is how you can do in slf4j + logback ecosystem

in logback.xml,

<configuration>
<appender name="consoleAppender" class="ch.qos.logback.core.ConsoleAppender">
    <encoder class="net.logstash.logback.encoder.LogstashEncoder">
        <timeZone>UTC</timeZone>
    </encoder>
</appender>
<logger name="com.yourcompany.packagename" level="INFO" additivity="false">
    <appender-ref ref="consoleAppender" />
</logger>
<root level="ERROR">
    <appender-ref ref="consoleAppender" />
</root>
</configuration>

Answer 3

This is in addition to what @robocode posted. Override the toString method in the Job class to print the parameters the way you would like to see them.

public class Job{
   String p1;
   int p2;
   .
   .
   @Override
   public String toString(){
      return "p1: "+p1+", p2: "+p2;
   }
}

Makes it easier to simply sysout your objects.

Job job = new Job();
System.out.println(job);

Answer 4

You can try adding Project Lombok to your Maven or Gradle file.

Use the annotation @Slf4j at class level and add log.info('text') anywhere in your class.

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class MyController {
   
   public void getAll() {
      
      // log is already initialized
      // use it anywhere in the annotated class
      log.info('This is a test.');

   }
}

Answer 5

如果以上没有解决问题，请确保您正在发出具有 sysout 语句的适当请求

Answer 6

import log4j dependency in your pom file

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

define logger in your controller like:

private static Logger logger = LoggerFactory.getLogger(YourClassName.class);

then use

logger.info("your message");