Question

我正在学习SpringBoot。我的（琐碎）问题是我无法从SpringBoot调用的CommandLineRunner接口中获取run（）方法。我正在使用Java 8，Eclipse Oxygen，Maven，并且将我的项目作为“ Spring Boot App”运行。代码是：

package com.clarivate.dataviewer;

import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.LogManager;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DvMain implements CommandLineRunner{

static Logger logger = LogManager.getRootLogger();

public static void main(String[] args) {
    logger.debug("DS1A in main()");
    //SpringApplication.run(DvMain.class, args);
    SpringApplication app = new SpringApplication(DvMain.class);
    //ConfigurableApplicationContext app = SpringApplication.run(DvMain.class, args);
    logger.debug("DS1B in main()");
    app.run(args);
}

@Override
public void run(String... args) throws Exception {
    // This does not get called
    logger.debug("DS4 this line is never printed");
}
}

不调用覆盖的run（）方法。我尝试创建一个单独的类来实现CommandLineRunner，但存在相同的问题。控制台跟踪为：

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Users/44/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Users/44/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.10.0/log4j-slf4j-impl-2.10.0.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]
12:58:42.225 [main] DEBUG  - DS1A in main()
12:58:42.289 [main] DEBUG  - DS1B in main()

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.2.RELEASE)

2018-06-20 12:58:42.614  INFO 16924 --- [           main] com.clarivate.dataviewer.DvMain          : Starting DvMain on 44-TPD-A with PID 16924 (C:\workspace_oxyegen\dataviewer\target\classes started by 44 in C:\workspace_oxyegen\dataviewer)
2018-06-20 12:58:42.615  INFO 16924 --- [           main] com.clarivate.dataviewer.DvMain          : No active profile set, falling back to default profiles: default
2018-06-20 12:58:42.655  INFO 16924 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@6b4a4e18: startup date [Wed Jun 20 12:58:42 BST 2018]; root of context hierarchy
2018-06-20 12:58:43.266  INFO 16924 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-06-20 12:58:43.279  INFO 16924 --- [           main] com.clarivate.dataviewer.DvMain          : Started DvMain in 0.988 seconds (JVM running for 1.684)
2018-06-20 12:58:43.294  INFO 16924 --- [       Thread-2] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@6b4a4e18: startup date [Wed Jun 20 12:58:42 BST 2018]; root of context hierarchy
2018-06-20 12:58:43.296  INFO 16924 --- [       Thread-2] o.s.j.e.a.AnnotationMBeanExporter        : Unregistering JMX-exposed beans on shutdown

我确定我犯了一个简单的错误，但是我看不到它。任何帮助表示赞赏。

Answer 1

首先，调用即将进入您的run方法。但是不记录任何内容，因为记录器存在一些问题。您可以使用System.out.println(...)进行确认。

按如下所示更改Logger声明。

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

您没有使用正确的库。使用 slf4j 中的Logger，而不使用 log4j
中的Logger
```
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
```

Answer 2

将logging.level.root=debug添加到您的application.properties文件。

默认情况下，Spring Boot不显示调试级别日志记录。之所以显示第一条调试消息，是因为它们在您的Spring应用程序启动之前被调用。

Answer 3

那是因为您的DvMain类本身未注释为Spring上下文@Component，所以spring无法找到pojo来执行您覆盖的run方法。

要解决此问题，只需将@Component添加到类中，您将在日志中看到跟踪。

SpringBoot CommandLineRunner run（）方法未被调用

3 个答案: