Why is Environment variable always null when reading from properties file?

Question

I am new to using application.properties and am struggling because Environment is always null. I have followed numerous examples such as the accepted answer shown on SO HERE; however, I keep getting the error message showing below. This is a Spring application and I know I don't actually need to go through this manual process per the article HERE. However, I have to show how to connect manually using the properties file. Where am I going wrong? Effectively, I want to hide my database credentials in application.properties and then read them into something like DriverManager.getConnection(env.getProperty("URL"), env.getProperty("USERNAME", env.getProperty("PASSWORD");

Attempting to use Environment:

@Component
@PropertySource("classpath:application.properties")
public class OpenConnection {
    private volatile Connection con;
    @Autowired
    private Environment env;


    public OpenConnection() {
    }

    @Bean
    public Connection getInstance() {
        try {
            DriverManagerDataSource dataSource = new DriverManagerDataSource();
            dataSource.setDriverClassName(env.getProperty("spring.datasource.driver-class-name"));
            dataSource.setUrl(env.getProperty("spring.datasource.url"));
            dataSource.setUsername(env.getProperty("spring.datasource.username"));
            dataSource.setPassword(env.getProperty("spring.datasource.password"));
            con = dataSource.getConnection();
        } catch (SQLException e) {
            handleException(e);
        }

        return con;
    }

application.properties

# MySQL
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/rentalportfolio?useTimezone=true&serverTimezone=UTC
spring.datasource.username=root
spring.datasource.password=root
spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect

Error message

java.lang.NullPointerException: null
    at com.crd.carrental.database.connectionoperations.OpenConnection.getInstance(OpenConnection.java:43) ~[classes/:na]
    at com.crd.carrental.database.selectoperations.SelectExistingReservation.<init>(SelectExistingReservation.java:24) ~[classes/:na]
    at com.crd.carrental.controllers.ExistingReservationController.lookupReservationId(ExistingReservationController.java:24) ~[classes/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_261]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_261]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_261]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_261]
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:171) ~[spring-messaging-5.3.3.jar:5.3.3]
    at org.springframework.messaging.handler.invocation.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:120) ~[spring-messaging-5.3.3.jar:5.3.3]
    at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMatch(AbstractMethodMessageHandler.java:565) [spring-messaging-5.3.3.jar:5.3.3]
    at org.springframework.messaging.simp.annotation.support.SimpAnnotationMethodMessageHandler.handleMatch(SimpAnnotationMethodMessageHandler.java:511) [spring-messaging-5.3.3.jar:5.3.3]
    at org.springframework.messaging.simp.annotation.support.SimpAnnotationMethodMessageHandler.handleMatch(SimpAnnotationMethodMessageHandler.java:94) [spring-messaging-5.3.3.jar:5.3.3]
    at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMessageInternal(AbstractMethodMessageHandler.java:520) [spring-messaging-5.3.3.jar:5.3.3]
    at org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler.handleMessage(AbstractMethodMessageHandler.java:454) [spring-messaging-5.3.3.jar:5.3.3]
    at org.springframework.messaging.support.ExecutorSubscribableChannel$SendTask.run(ExecutorSubscribableChannel.java:144) [spring-messaging-5.3.3.jar:5.3.3]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_261]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_261]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_261]

If you are using spring boot I would recommend letting spring configure the connection:spring.datasource.driverClassName=${JDBC_DATASOURCE_DRIVER_CLASS_NAME}, spring.datasource.url, spring.datasource.username, spring.datasource.password in application.properties — Luis Acero, Mar 02 '21 at 21:03
@LuisAcero I just edited my post to show my application.properties file. I am not sure how to implement what you're suggesting though? — Michael, Mar 02 '21 at 21:16
Ditch your configuration and let spring boot take care of the `DataSource`. You are currently working around that, nor is this the correct way to obtain a JDBC connection. — M. Deinum, Mar 03 '21 at 07:20

score 1 · Answer 1 · answered Mar 02 '21 at 21:20

1

I recommend removing this OpenConnection class and let SpringBoot create your datasource for you on start up.

If you really want to create it yourself, check the docs. Here is an example:

@Configuration
public class DataSourceConfiguration {

   @Bean
   @ConfigurationProperties("spring.datasource")
    public DataSource dataSource() {
        return DataSourceBuilder.create().build();
    }
}

answered Mar 02 '21 at 21:20

Chris Savory

2,597
1
17
27

Thank you @ChrisSavory. I need to create it myself though. I just can't figure out how to read from my application.properties file. Is there a way I can do that? – Michael Mar 02 '21 at 21:23
Yes, i just showed you how in my answer. Does it work? – Chris Savory Mar 02 '21 at 21:25
Thank you for the clarification! What is "spring.datasource" in this case? – Michael Mar 02 '21 at 21:28
1

Those are all your properties in your yaml or properties files. E.g. `spring.datasource.username` and `spring.datasource.password` – Chris Savory Mar 02 '21 at 21:45
1

You really need to read through this section. https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#howto-configure-a-datasource – Chris Savory Mar 02 '21 at 21:45

score 1 · Accepted Answer · answered Mar 02 '21 at 21:49

1

I think that the problem is that you are using @Component on your OpenConnection rather than @Configuration

Here you can find some more examples, how to use properties in your Spring application

answered Mar 02 '21 at 21:49

mehowthe

761
6
14

Why is Environment variable always null when reading from properties file?

2 Answers2