春季启动

春季启动

关注
发信
关注(28)粉丝(399)

春季启动-@PostConstruct未在@Component上调用

本文介绍了春季启动-@PostConstruct未在@Component上调用的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

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 1In 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. 此处和此处.有几种解决方法:

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-api dependency 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;

这篇关于春季启动-@PostConstruct未在@Component上调用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！

08-06 11:50
Powered by LMLPHP ©2024 春季启动 0.049118