Java 从 application.properties Spring Boot 读取值
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/45428826/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Reading values from application.properties Spring Boot
提问by Karan
My Spring boot app has this application structure:
我的 Spring Boot 应用程序具有以下应用程序结构：
- src
- main
- java
- resources
- application.properties
- main
- 源文件
- 主要的
- 爪哇
- 资源
- 应用程序属性
- 主要的
This is my application.properties file:
这是我的 application.properties 文件：
logging.level.org.springframework=TRACE
logging.level.org.hibernate=ERROR
spring.resources.chain.strategy.content.enabled=true
spring.resources.chain.strategy.content.paths=/**
#spring.resources.chain.cache=false
#spring.resources.chain.html-application-cache=false
#spring.headers.cache=false
language=java
I have a class which requires the use of that language=java property. This is how I am trying to use it:
我有一个需要使用该 language=java 属性的类。这就是我尝试使用它的方式：
public class EntityManager {
@Value("${language}")
private static String newLang;
public EntityManager(){
System.out.println("langauge is: " + newLang);
}
}
That printed value is always "null"for some reason! I have also tried putting this on top of the class declaration:
由于某种原因，该打印值始终为“空”！我也试过把它放在类声明的顶部：
@PropertySource(value = "classpath:application.properties")
回答by Barath
Missing stereotype annotation on top of class
缺少类顶部的构造型注释
@Component
public class EntityManager {
@Value("${language}")
private static String newLang;
public EntityManager(){
System.out.println("langauge is: " + newLang);
}
}
回答by Mayank Sharma
you can try to use @PropertySourceand give it the path to property file, you can find the sample below:
您可以尝试使用@PropertySource并为其指定属性文件的路径，您可以在下面找到示例：
@Component
@PropertySource("classpath:application.properties")
public class EntityManager {
@Value("${language}")
private static String newLang;
public EntityManager(){
System.out.println("langauge is: " + newLang);
}
}
回答by Ognjen Mi?i?
Probably not the exact solution you're looking for, but you can also declare a property source bean:
可能不是您正在寻找的确切解决方案，但您也可以声明一个属性源 bean：
回答by Anil Kumar Athuluri
It can be achieved in multiple ways, refer below.
它可以通过多种方式实现，请参阅下文。
@Configuration
@PropertySource("classpath:application.properties")
public class EntityManager {
@Value("${language}")
private static String newLang;
@Bean
public static PropertySourcesPlaceholderConfigurer propertyConfigInDev() {
return new PropertySourcesPlaceholderConfigurer();
}
}
OR
或者
@Configuration
@PropertySource("classpath:application.properties")
public class EntityManager {
@Autowired
private Environment env;
public void readProperty() {
env.getProperty("language");
}
}
回答by Karan
OK I figured it out with acts of desperation. I added the
好吧，我用绝望的行为想通了。我添加了
@PropertySource("classpath:application.properties")
attribute but it still wasn't working for some reason.
属性，但由于某种原因它仍然不起作用。
I then deleted the "static" modifier and it worked!
然后我删除了“静态”修饰符，它起作用了！
I am not sure why it works without "static" being there but it does. If can explain it to me that would be wonderful because this is all confusing.
我不确定为什么它在没有“静态”的情况下工作，但确实如此。如果可以向我解释它会很棒，因为这一切都令人困惑。
回答by Mayank Madhav
Sometimes, the classpath entry for src/main/resourcescontains an exclude tag. If application.propertiesis present in this list of excluded items then @PropertySource("classpath:application.properties")will not be able to find the property file.
有时， 的类路径条目src/main/resources包含排除标记。如果application.properties出现在此排除项目列表中，@PropertySource("classpath:application.properties")则将无法找到属性文件。
Either remove the exclude entry from [.classpath][1]file for src/main/resourcesmanually, or use the Configure build path option in Eclipse and go to Source tab. Then remove the exclude entry from src.
手动从[.classpath][1]文件中删除排除条目src/main/resources，或使用 Eclipse 中的配置构建路径选项并转到源选项卡。然后从 中删除排除条目src。
回答by BazSTR
create you beans
为你创造豆子
@Configuration
@PropertySource("classpath:application.properties")
public class ApplicationBeansConfig {
@Autowired
Environment env;
@Bean
public IApplicationBeanService getService(){
return new ApplicationBeansService(env);
}
}
and then in service costructor
然后在服务构造函数中
@Service
public class ApplicationBeansService implements IApplicationBeanService {
...
public ApplicationBeansService(Environment env){
...
String value = env.getProperty("your.value")
...
}
...
}
don't forget fill your application.properties:
不要忘记填写您的 application.properties：
your.value = some-string-value
回答by Anindya Mukherjee
If you are using Spring boot you do not need @PropertySource("classpath:application.properties")if you are using spring boot starter parent , just remove the statickeyword and it should start working.
如果您使用的是 Spring boot，@PropertySource("classpath:application.properties")如果您使用的是 spring boot starter parent ，则不需要，只需删除static关键字，它就会开始工作。
回答by hello_earth
in my case, the same problem had a slightly different cause - i had a class with a static instance variable (the old usual way we used to implement a Singleton pattern), into which i wanted to inject an entry from application.properties (probably the "static" thing was why the property could not be found - with no errors no anything :/).
在我的例子中，同样的问题有一个稍微不同的原因 - 我有一个带有静态实例变量的类（我们用来实现单例模式的旧常用方法），我想从 application.properties 注入一个条目（可能是“静态”的事情是为什么找不到属性 - 没有错误没有任何东西:/)。
moreover this class was in a totally different package from the class declared as @SpringBootApplication. i understood that package names and locations have to be taken into serious consideration with Spring Boot and automatic component scanning. my 5 cent
此外，这个类与声明为@SpringBootApplication 的类在一个完全不同的包中。我知道使用 Spring Boot 和自动组件扫描必须认真考虑包名称和位置。我的 5 美分
回答by VC2019
As provided in the 2nd answer above I was indeed using the spring boot, so removed the static keyword and that resolved my issue. Make sure you don't have static for the property defined with @Value.
正如上面的第二个答案中提供的那样，我确实使用了弹簧靴，因此删除了 static 关键字并解决了我的问题。确保您没有使用 @Value 定义的属性的静态。
