spring @Value get the configuration file is null common ways

The first way:

xx.properties error attribute name, is not performed corresponding @Value ( "$ {xxx}")

 

The second way:

Such spring bean not injected into the vessel

@Component

@Controller

@Service

# The above is not injected, using @Autowired will complain

@Autowired

The third way:

Using new obtain this object, etc.

 @Component   
    class TestValue{
         @Value("${tag}")
         private String tagValue;
    }

    class Test{
        ...
        TestValue testValue = new TestValue()
    }
\

 

The fourth way

The static final properties with other words be modified

@Value("${value}")
private static String value;  //错误

@Value("${value}")
private final String value; //错误

 

Fifth way 

The property name in uppercase

@Value("${value}")
private static String VALUE;  //错误

Reference documents: https://blog.csdn.net/zzmlake/article/details/54946346

 

The fifth way is what I really met, if there are other ways will lead to @Value ( "$ {xxx}") is null,

Please leave a message at the bottom,