Spring-使用值批注从本地配置文件读取

Question

I am trying to use the Value annotation in Spring to read from the local application.yaml file I put in the same package as my main and unit test class. I have a simple class with the method that gets the config value:

public class EmailValidator {

    String getConfigValue(configurationProvider1 configurationReader, String configName) {
        String value = null;
        ConfigurationProvider reader;
        try {
            reader = configurationReader.configurationProvider();
            value = reader.getProperty(configName, String.class);
            //the `reader` above is null when I run the test, so I get Null Pointer Exception on this line
            if (value == null) {
                LOGGER.warn("The configuration for " + configName + " cannot be found.");
            }
        } catch (Exception e){
            e.printStackTrace();
        }

        return value;
    }
} 

And I have a configuration provider class which sets the configuration reader so that my class above can make use of it to read the application.yaml file:

@Configuration
@AllArgsConstructor(access = AccessLevel.PACKAGE)
@NoArgsConstructor
@ComponentScan
public class configurationProvider1 {

        @Value("${configFilesPath:./domain/application.properties}")//Not really sure if this is the right way of locating my configuration file
        @Getter
        private String filePath;

        @Bean
        public ConfigurationProvider configurationProvider() throws FileNotFoundException {
            if (!Paths.get(this.filePath).toFile().exists()) {
                throw new FileNotFoundException("Configuration file doesn't exist: " + this.filePath);
            }

            ConfigFilesProvider configFilesProvider =
                    () -> Collections.singletonList(Paths.get(filePath).toAbsolutePath());
            ConfigurationSource source = new FilesConfigurationSource(configFilesProvider);
            Environment environment = new ImmutableEnvironment(this.filePath);

            return new ConfigurationProviderBuilder()
                    .withConfigurationSource(source)
                    .withEnvironment(environment)
                    .build();
        }
    } 

As commented above, I'm not sure if @Value("${configFilesPath:./domain/application.properties}") is a right way of locating my local application.properties file (The classes are in the same package called domain but the config file is not in the resources folder since this is a service layer. So it is just right under the domain package).

And when I try to test my getConfigValue method in my first class, I get NPE (I assume its because the configurationReader I am passing in as a parameter to getConfigValue method is null):

@RunWith(SpringRunner.class)
@SpringBootTest
public class EmailValidatorTest {

    @MockBean
    private configurationProvider1 configurationReader = mock(configurationProvider1.class);

    @Autowired
    private DefaultEmailValidator validator;//maybe I should inject the dependency somewhere?

    @Test
    public void simple(){
        String a = validator.getConfigValue(configurationReader,"mail.subject.max.length");
        System.out.println(a);
    } 

I am not sure if my class is actually reading the config value from the config file at this point. Any help would be greatly appreciated!

PS The code is updated

Answer 1

@Value

Spring's @Value annotation provides a convenient way to inject property values into components, not to provide the properties file path

@PropertySource Use @PropertySource for that Doc

Annotation providing a convenient and declarative mechanism for adding a PropertySource to Spring's Environment. To be used in conjunction with @Configuration classes

Given a file app.properties containing the key/value pair testbean.name=myTestBean , the following @Configuration class uses @PropertySourc e to contribute app.properties to the Environment's set of PropertySources.

Example

 @Configuration
 @PropertySource("classpath:/com/myco/app.properties")
 public class AppConfig {

 @Autowired
 Environment env;

 @Bean
 public TestBean testBean() {
     TestBean testBean = new TestBean();
     testBean.setName(env.getProperty("testbean.name"));
     return testBean;
   }
 }

24.7.4 YAML Shortcomings

YAML files cannot be loaded by using the @PropertySource annotation. So, in the case that you need to load values that way, you need to use a properties file.

Coming to Test case you should not create new instance of DefaultEmailValidator you need to use @SpringBootTest

@SpringBootTest Example

The @SpringBootTest annotation can be used when we need to bootstrap the entire container. The annotation works by creating the ApplicationContext that will be utilized in our tests.

RunWith(SpringRunner.class)

@RunWith(SpringRunner.class) is used to provide a bridge between Spring Boot test features and JUnit. Whenever we are using any Spring Boot testing features in out JUnit tests, this annotation will be required.

@MockBean

Another interesting thing here is the use of @MockBean. It creates a Mock

EmailValidatorTest

 @RunWith(SpringRunner.class)
 @SpringBootTest
 public class EmailValidatorTest {

@MockBean
private configurationProvider1 configurationReader;

@Autowire
private DefaultEmailValidator validator

@Test
public void testGetConfigValue(){
    String a = validator.getConfigValue(configurationReader,"mail.subject.max.length");
    System.out.println(a);
}