In Spring what is the difference between @Profile and @ActiveProfiles

Spring Profiles provide a way to segregate parts of your application configuration.

Any @Component or @Configuration can be marked with @Profile to limit when it is loaded which means that component or configuration will be loaded in the application context only when the active profiles is same as the profile mapped to a component.

To mark a profile active, spring.profiles.active property must be set in application.properties or given as an VM argument as -Dspring.profiles.active=dev

While writing Junit, you would want to activate some profile so as to load the required configuration or Component. Same can be achieved by using @ActiveProfile annotation.

Consider a configuration class which is mapped to profile dev

@Configuration
@Profile("dev")
public class DataSourceConfig {
    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost/test");
        ds.setUsername("root");
        ds.setPassword("mnrpass");
        return ds;
    }

    @Bean
    public JdbcTemplate jdbcTemplate() {
        return new JdbcTemplate(dataSource());
    }
}

Consider a configuration class which is mapped to profile prod

@Configuration
@Profile("prod")
public class DataSourceConfig {
    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:oracle://xxx.xxx.xx.xxx/prod");
        ds.setUsername("dbuser");
        ds.setPassword("prodPass123");
        return ds;
    }

    @Bean
    public JdbcTemplate jdbcTemplate() {
        return new JdbcTemplate(dataSource());
    }
}

So, if you want to run your junit test cases in dev profile then you have to use the @ActiveProfile('dev') annotation. This will load the DataSourceConfig bean defined in dev profile.

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
@ActiveProfiles("dev")
public class Tests{

    // Junit Test cases will use the 'dev' profile DataSource Configuration

}

Conclusion

@Profile is used to map a class to a profile

@ActiveProfile is used to activate a particular profile(s) during junit test class execution