小编典典

春季启动-@PostConstruct未在@Component上调用

java

我是spring的新手,我使用https://start.spring.io/创建了一个新的spring
boot项目,没有更多依赖关系,解压缩了zip文件并在IntelliJ
IDEA中打开了该项目。我没有做任何进一步的配置。我现在正在尝试使用@PostConstruct方法设置bean-但是,该方法从未被spring调用。

这些是我的课程:

SpringTestApplication.java

package com.habichty.test.testspring;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ConfigurableApplicationContext;

@SpringBootApplication
    public class SpringTestApplication {

        public static void main(String[] args) {
            ConfigurableApplicationContext context = SpringApplication.run(SpringTestApplication.class, args);
            context.getBean(TestBean.class).testMethod();
        }
    }

TestBean.java

package com.habichty.test.testspring;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;
import javax.annotation.PostConstruct;

@Component  
    public class TestBean {
            private final Logger log = LoggerFactory.getLogger(this.getClass());
            private int a = 1;

            public TestBean()
            {
                log.debug("Constructor of TestBean called.");
            }

            @PostConstruct
            public void init()
            {
                log.debug("init()-Method of TestBean called.");
                a = 2;
            }

            public void testMethod()
            {
                log.debug("Test Method of TestBean called. a=" + a);
            }

        }

当我启动应用程序时,这是我的输出:

 :: Spring Boot ::        (v1.5.9.RELEASE)

2018-01-22 13:15:57.960  INFO 12035 --- [           main] c.h.t.testspring.SpringTestApplication   : Starting SpringTestApplication on pbtp with PID 12035 (/home/pat/prj/testspring/testspring/target/classes started by pat in /home/pat/prj/testspring/testspring)
2018-01-22 13:15:57.962 DEBUG 12035 --- [           main] c.h.t.testspring.SpringTestApplication   : Running with Spring Boot v1.5.9.RELEASE, Spring v4.3.13.RELEASE
2018-01-22 13:15:57.962  INFO 12035 --- [           main] c.h.t.testspring.SpringTestApplication   : No active profile set, falling back to default profiles: default
2018-01-22 13:15:58.018  INFO 12035 --- [           main] s.c.a.AnnotationConfigApplicationContext : Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext@2931522b: startup date [Mon Jan 22 13:15:58 CET 2018]; root of context hierarchy
2018-01-22 13:15:58.510 DEBUG 12035 --- [           main] com.habichty.test.testspring.TestBean    : Constructor of TestBean called.
2018-01-22 13:15:58.793  INFO 12035 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-01-22 13:15:58.822  INFO 12035 --- [           main] c.h.t.testspring.SpringTestApplication   : Started SpringTestApplication in 1.073 seconds (JVM running for 2.025)
2018-01-22 13:15:58.822 DEBUG 12035 --- [           main] com.habichty.test.testspring.TestBean    : Test Method of TestBean called. a=1
2018-01-22 13:15:58.826  INFO 12035 --- [       Thread-1] s.c.a.AnnotationConfigApplicationContext : Closing org.springframework.context.annotation.AnnotationConfigApplicationContext@2931522b: startup date [Mon Jan 22 13:15:58 CET 2018]; root of context hierarchy
2018-01-22 13:15:58.828  INFO 12035 --- [       Thread-1] o.s.j.e.a.AnnotationMBeanExporter        : Unregistering JMX-exposed beans on shutdown

如您所见,spring初始化了TestBean并执行了testMethod(),但是没有调用以@PostConstruct注释的init()-Method。

我究竟做错了什么?任何帮助都非常感谢。

更新1 在我的application.properties中,我已配置:

logging.level.com = DEBUG

将其更改为 logging.level.root = DEBUG会 导致更大的日志。但是,它仍然不包含我的init()方法的调试消息。

更新2 添加了package和import语句。

更新3
为了进一步说明这不是日志记录问题,我向应该由init()-Method更改的代码中添加了一个新的int。据我了解@PostConstruct批注的概念,应该在执行任何其他方法之前执行它。结果,testMethod()的输出现在应该包含
a = 2 。在更新的输出中,您可能会发现情况并非如此。

更新4 这是我的POM

    <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.habichty.test.testspring</groupId>
    <artifactId>springTest</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>springTest</name>
    <description>springTest</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.9.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

输出java -version

java version "9.0.1"
Java(TM) SE Runtime Environment (build 9.0.1+11)
Java HotSpot(TM) 64-Bit Server VM (build 9.0.1+11, mixed mode)

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2020-11-26

共1个答案

小编典典

由于Java9中的新模块系统SpringBoot-1.5.9无法处理,@PostConstruct因为注释类不在类路径中。问题(或类似问题)在此处此处进行描述。有几种解决方法:

  • 使用Java8运行该应用程序,
    或者如果仍在Java9上运行该应用程序:

  • javax.annotation:javax.annotation-api向POM 添加依赖项,或

  • 升级到更新的2.0.0+版本的Spring-Boot(在撰写本文时仍为PRERELEASE),其中包含该依赖项;
2020-11-26