春季启动-@PostConstruct未在@Component上调用 [英] spring boot - @PostConstruct not called on @Component
问题描述
我是spring的新手，并且我已经使用 https://start.spring创建了一个新的spring boot项目.没有进一步依赖性的io/，解压缩了zip文件，并在IntelliJ IDEA中打开了项目.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，该方法永远不会被spring调用.
I am new to spring, and I have created a new spring boot project using https://start.spring.io/ with no further dependencies, unzipped the zip file and opened the project in IntelliJ IDEA. I have not done any further configurations. I am now trying to setup a bean with a @PostConstruct method - however, the method is never invoked by spring.
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);
}
}
启动应用程序时，这是我的输出:
When I start the application, this is my output:
:: 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会初始化TestBean并执行testMethod()-但不会调用以@PostConstruct注释的init()-Method.
As you can see, spring initializes the TestBean and also executes the testMethod() - but the init()-Method, annotated with @PostConstruct, is not invoked.
我做错了什么? 任何帮助都非常感谢.
What am I doing wrong? Any help is very appreciated.
更新1 在我的application.properties中，我已配置:
UPDATE 1 In my application.properties, I have configured:
logging.level.com = DEBUG
将此更改为 logging.level.root = DEBUG 会导致日志大得多.但是，它仍然不包含我的init()方法的调试消息.
Changing this to logging.level.root = DEBUG results in a massively bigger log. However, it still does not contain the debug message of my init() method.
更新2 添加了打包和导入语句.
UPDATE 2 Added package and import statements.
更新3 为了进一步说明这不是日志记录问题，我在代码中添加了一个新的int，该int应该由init()-Method进行更改.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.因此，testMethod()的输出现在应包含 a = 2 .在更新的输出中，您可能会发现情况并非如此.
UPDATE 3 To further clarify that this is not a logging issue, I have added an new int to the code that should be altered by the init()-Method. As far as I understood the concept of the @PostConstruct annotation, it should be executed prior to any other method execution. As a consequence, the output of testMethod() should now contain a=2. In the updated output, you may see that this is not the case.
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>
java -version的输出:
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)
推荐答案
由于Java9中的新模块系统，由于注释类不在类路径中，因此SpringBoot-1.5.9无法处理@PostConstruct. 此处和
Due to the new module system in Java9 SpringBoot-1.5.9 fails to process @PostConstruct as the annotation class is not on the classpath. The problem (or similar) is described here and here. There are a few ways to resolve it:
- 使用Java8，
或(如果仍在Java9上)运行应用程序: - 将
javax.annotation:javax.annotation-api依赖项添加到POM，或者 - 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；
- run the application with Java8,
or, if still on Java9: - add
javax.annotation:javax.annotation-apidependency to the POM, or - upgrade to a newer Spring-Boot of version 2.0.0+ (which is still PRERELEASE as of this writing) which incorporates that dependency;
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