弹簧4力属性待定义

Question

In spring I can retrieve property(defined in properties file) using getProperty method(of Environment) Eg

@PropertySource("classpath:app.properties")
public class Config{
    @Autowired
    Environment env;

@Bean 
public Foo foo(){
 env.getProperty("foo.isEligible")
//.... return foo.
}
}

however if the property is not defined then it returns null . We could make a null check and throw exception explicitly but is there some built-in method in spring to achieve it, so that application will throw exception if the property requested via getProperty method is not defined . I am using spring 4.

Answer 1

You can use getRequiredProperty which throws IllegalStateException if property is undefined. Eg

env.getRequiredProperty("foo");

Answer 2

If you want an error at Spring startup time, if you used something like

@Value("${foo.isEligible}")
protected boolean isFooEligible;

The Spring ApplicationContext will fail to startup if it can't resolve this SpEL expression