Spring Boot application.properties 值未填充 [英] Spring Boot application.properties value not populating
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问题描述
我有一个非常简单的 Spring Boot 应用程序，我正在尝试使用一些外部化配置.我试图遵循 spring boot 上的信息文档但是我遇到了障碍.
I have a very simple Spring Boot app that I'm trying to get working with some externalised configuration. I've tried to follow the information on the spring boot documentation however I'm hitting a road block.
当我在 application.properties 文件中的外部配置下运行应用程序时，不会填充到 bean 中的变量中.我确定我在做一些愚蠢的事情，感谢您的任何建议.
When I run the app below the external configuration in the application.properties file does not get populated into the variable within the bean. I'm sure I'm doing something stupid, thanks for any suggestions.
MyBean.java(位于/src/main/java/foo/bar/)
MyBean.java (located in /src/main/java/foo/bar/)
package foo.bar;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.stereotype.Component;
@Component
public class MyBean {
@Value("${some.prop}")
private String prop;
public MyBean() {
System.out.println("================== " + prop + "================== ");
}
}
Application.java(位于/src/main/java/foo/)
Application.java (located in /src/main/java/foo/)
package foo;
import foo.bar.MyBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.SpringApplication;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
@Configuration
@ComponentScan
@EnableAutoConfiguration
public class Application {
@Autowired
private MyBean myBean;
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
}
application.properties(位于/src/main/resources/)
application.properties (located in /src/main/resources/)
some.prop=aabbcc
执行 Spring Boot 应用程序时的
日志输出:
Log output when executing the Spring Boot app:
grb-macbook-pro:properties-test-app grahamrb$ java -jar ./build/libs/properties-test-app-0.1.0.jar
. ____ _ __ _ _
/\ / ___'_ __ _ _(_)_ __ __ _
( ( )\___ | '_ | '_| | '_ / _` |
\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v1.1.5.RELEASE)
2014-09-10 21:28:42.149 INFO 16554 --- [ main] foo.Application : Starting Application on grb-macbook-pro.local with PID 16554 (/Users/grahamrb/Dropbox/dev-projects/spring-apps/properties-test-app/build/libs/properties-test-app-0.1.0.jar started by grahamrb in /Users/grahamrb/Dropbox/dev-projects/spring-apps/properties-test-app)
2014-09-10 21:28:42.196 INFO 16554 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@67e38ec8: startup date [Wed Sep 10 21:28:42 EST 2014]; root of context hierarchy
2014-09-10 21:28:42.828 INFO 16554 --- [ main] o.s.b.f.s.DefaultListableBeanFactory : Overriding bean definition for bean 'beanNameViewResolver': replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]
2014-09-10 21:28:43.592 INFO 16554 --- [ main] .t.TomcatEmbeddedServletContainerFactory : Server initialized with port: 8080
2014-09-10 21:28:43.784 INFO 16554 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat
2014-09-10 21:28:43.785 INFO 16554 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/7.0.54
2014-09-10 21:28:43.889 INFO 16554 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2014-09-10 21:28:43.889 INFO 16554 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1695 ms
2014-09-10 21:28:44.391 INFO 16554 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2014-09-10 21:28:44.393 INFO 16554 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
================== null==================
2014-09-10 21:28:44.606 INFO 16554 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2014-09-10 21:28:44.679 INFO 16554 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2014-09-10 21:28:44.679 INFO 16554 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],methods=[],params=[],headers=[],consumes=[],produces=[text/html],custom=[]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest)
2014-09-10 21:28:44.716 INFO 16554 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2014-09-10 21:28:44.716 INFO 16554 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2014-09-10 21:28:44.902 INFO 16554 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2014-09-10 21:28:44.963 INFO 16554 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080/http
2014-09-10 21:28:44.965 INFO 16554 --- [ main] foo.Application : Started Application in 3.316 seconds (JVM running for 3.822)
^C2014-09-10 21:28:54.223 INFO 16554 --- [ Thread-2] ationConfigEmbeddedWebApplicationContext : Closing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@67e38ec8: startup date [Wed Sep 10 21:28:42 EST 2014]; root of context hierarchy
2014-09-10 21:28:54.225 INFO 16554 --- [ Thread-2] o.s.j.e.a.AnnotationMBeanExporter : Unregistering JMX-exposed beans on shutdown
推荐答案
你执行属性注入的方式是行不通的，因为注入是在调用构造函数之后完成的.
The way you are performing the injection of the property will not work, because the injection is done after the constructor is called.
您需要执行以下操作之一:
You need to do one of the following:
更好的解决方案
@Component
public class MyBean {
private final String prop;
@Autowired
public MyBean(@Value("${some.prop}") String prop) {
this.prop = prop;
System.out.println("================== " + prop + "================== ");
}
}
可行但可测试性和可读性稍差的解决方案
@Component
public class MyBean {
@Value("${some.prop}")
private String prop;
public MyBean() {
}
@PostConstruct
public void init() {
System.out.println("================== " + prop + "================== ");
}
}
另请注意，这不是 Spring Boot 特定的，而是适用于任何 Spring 应用程序
Also note that is not Spring Boot specific but applies to any Spring application
这篇关于Spring Boot application.properties 值未填充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IT屋！
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