Accessing AWS Lambda environment variables in Java code

you can get them with:

System.getenv("NAME_OF_YOUR_ENV_VARIABLE")

If You are using Spring Core then PropertySourcesPlaceholderConfigurer class can be initialized as a part of Configuration and then @Value("${RESOURCE_URL}") annotation can be used to access environment variables.

@Bean
public static PropertySourcesPlaceholderConfigurer placeholderConfigurer() {
    return new PropertySourcesPlaceholderConfigurer();
}

@Value("${RESOURCE_URL}")
private String url;