Reading application.properties from any class in spring boot - properties

Question

When I add a property in the application.properties files, this can be access from the main class without any problem.
#SpringBootApplication
#ComponentScan(basePackages = "com.example.*")
public class MailTestApplication implements CommandLineRunner {
#Value("${admin.mail}")
String email;
public static void main(String[] args) {
SpringApplication.run(MailTestApplication.class, args);
}
#Override
public void run(String... strings) throws Exception {
System.out.println(email);
Email email = new Email();
email.sendMail();
}
}
However, when I try to access it from any other class it is never retrieved.
#Component
public class Email {
#Autowired
private MailSender sender;
#Value("${admin.mail}")
String email;
public Email() {
}
public void sendMail() {
SimpleMailMessage msg = new SimpleMailMessage();
System.out.println(email);
msg.setTo("sample#email.com");
msg.setSubject("Send mail by Spring Boot");
msg.setText("Send mail by Spring Boot");
sender.send(msg);
}
}
I was reading some of the previous questions other users posted without a clear result for me. I even tried to find some examples with similar resutl.
Could someone give me any clue about this?
Thanks a lot in advance.

Answer 1

The #Value should work (Im asuming your class is under the com.example.* package since you are scanning that package) but if you want to do it another way this is what im using :
public class JpaConfiguration {
public static final String TRANSACTION_MANAGER_NAME = "jpaTransactionManager";
#Autowired
Environment applicationProperties;
Then to use it
#Bean
public DriverManagerDataSource driverManagerDataSource() {
DriverManagerDataSource driverConfig = new DriverManagerDataSource();
driverConfig.setDriverClassName(applicationProperties.getProperty("data.jpa.driverClass"));
driverConfig.setUrl(applicationProperties
.getProperty("data.jpa.connection.url"));
driverConfig.setUsername(applicationProperties
.getProperty("data.jpa.username"));
driverConfig.setPassword(applicationProperties
.getProperty("data.jpa.password"));
return driverConfig;
}
UPDATE AFTER GETTING THE GITHUB REPO
I Don't really know what you are trying to build but :
If you do this:
#Override
public void run(String... strings) throws Exception {
//System.out.println(email);
Email email = new Email();
email.sendMail();
}
Then you are creating the instance of the class, and not spring. so you shouldn't be creating the instance yourself there it should be spring.
That said, i dont know if you are creating a web application a command line application or both.
That said ill give you a minor solution to show you that the dependency injection is in fact working.
1_ add a getter to your email on email class. remove the CommandLine interface (If you want to implement this i would recomend you to put CommandLine implmentations on another package say Controller);
And then run your app like this:
#SpringBootApplication
#ComponentScan(basePackages = "com.example")
public class MailTestApplication {
#Value("${admin.mail}")
String email;
public static void main(String[] args) {
// SpringApplication.run(MailTestApplication.class, args);
final ConfigurableApplicationContext context = new SpringApplicationBuilder(MailTestApplication.class).run(args);
Email e = context.getBean(Email.class);
System.out.println(e.getEmail());
}
The Key thing I want to show is that the instance is created by spring thats why the wiring works. and the email gets printed in the console.
Regarding the email class :
#Component
public class Email {
// #Autowired
// private MailSender sender;
#Value("${admin.mail}")
String email;
public Email() {
}
public void sendMail() {
SimpleMailMessage msg = new SimpleMailMessage();
System.out.println(email);
msg.setTo("sample#email.com");
msg.setSubject("Send mail by Spring Boot");
msg.setText("Send mail by Spring Boot");
// sender.send(msg);
}
public String getEmail() {
return email;
}
}
I Comment out the MailSender since I think you need to configure that too, i have made a custom mailSender that uses gmail and other for mailChimp that i can share with you if you need. but again I dont really know what your intent with the app is.
Hope the info helps you.