Spring的环境抽象是否使用PropertyEditor？

Question

My google-fu is failing me on this one.

I'm using Spring 4.2.4.RELEASE with java configuration. What I'm trying to do is register a custom property editor to convert from a String to a Map.

So I have a Java Configuration class that registers the appropriate BeanFactoryPostProcessor

@Bean
public static CustomEditorConfigurer customEditorConfigurer(){
    CustomEditorConfigurer configurer = new CustomEditorConfigurer();
    Map<Class<?>, Class<? extends PropertyEditor>> customEditors = new HashMap<>();
    customEditors.put(Map.class, DelimitedStringToMapPropertyEditor.class);
    configurer.setCustomEditors(customEditors);


    return configurer;
}

In the same configuration class I am also injecting the Environment

@Resource
private Environment environment;

However, when I try to get the String property (which is also unfortunately named environment ) that I want converted to a map, I get an exception.

environment.getProperty("environment", Map.class, Collections.EMPTY_MAP)

Exception:

Caused by: java.lang.IllegalArgumentException: Cannot convert value [VAR=hello] from source type [String] to target type [Map]
at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:94)
at org.springframework.core.env.PropertySourcesPropertyResolver.getProperty(PropertySourcesPropertyResolver.java:65)
at org.springframework.core.env.AbstractPropertyResolver.getProperty(AbstractPropertyResolver.java:143)
at org.springframework.core.env.AbstractEnvironment.getProperty(AbstractEnvironment.java:546)

BUT if I inject the property directly using the @Value annotation, it works just fine.

@Value("${environment}")
private Map<String, String> shellEnvironment;

So, what gives? Does the Environment object not take into account registered property editors? Do I need to create a custom Converter ? Isn't the Environment abstraction the latest and greatest way to resolve properties that come from anywhere?

Answer 1

No ; the Environment abstraction does not use registered Property Editors. It only resolves properties (and does basic Type Conversion).

---

Thanks to the comments from @M. Deinum I was able to come to a decent compromise.

Correct it is a way to resolve properties it isn't a way to convert properties. When using the @Value 2 things happen, first the property is resolved, second conversion is attempted (only basic conversion String to numbers/booleans is done through plain java not converters/editors.). You only do the resolution part not the conversion part. – M. Deinum

You have to kind of read between the lines in the reference manual to come to this understanding.

The Environment Abstraction chapter states:

The role of the Environment object with relation to properties is to provide the user with a convenient service interface for configuring property sources and resolving properties from them .

Notice it does not say anything about conversion/editors. (Although I did notice that it does actually handle simple Type Conversion because Environment inherits PropertyResolver.getPropertyAsClass )

So I decided to combine the two methods and settled on this method of injecting my properties into my configuration class:

@Resource
private Environment environment;

@Value("#{environment['environment']?:{:}}")
private Map<String, String> shellEnvironment;