Does Spring store all properties into a single hashmap?-CodePudding

Does Spring put all properties into the same hashmap/list?
How can I get a list of all of the properties being managed by Spring

For example, if I have two properties files and they define overlapping properties which

// FILE: src/main/resources/file1.properties
prop1.color = red
prop1.fill  = green

// FILE: src/main/resources/file2.properties
prop2.color = purple
prop1.fill  = ORANGE

The configuration class used to tell Spring to read the two files is something like this:

@PropertySource("classpath:file1.properties")
@PropertySource("classpath:file2.properties")
@Configuration
public class MyConfig {
}

My question is Can I get an iterator to access all of the properties defined? If so how.

Searching for answer

So far I haven't found a solution to this question.

I did an Internet search for "stack overflow Spring properties" and did not found the answer.

Some SO questions I found are:

But they didn't answer my question

CodePudding user response：

Spring provides a PropertySources interface which is implemented by the MutablePropertySources class. This class basically just holds a list of PropertySource instances (e.g. instances of the PropertiesPropertySource class) and provides methods for iterating over these instances.

If you look at the implementation of MutablePropertySources you can see that there are multiple methods for adding PropertySource instances at different positions and relative to other PropertySources in that list. If you want to get a property, the get method of the MutablePropertySources is called which iterates over all PropertySources until it finds that property.

Then there is the Environment interface that is implemented by the abstract class AbstractEnvironment. You can use the latter to access the PropertySources instance.

For example, you can do:

@PropertySource("classpath:file1.properties")
@PropertySource("classpath:file2.properties")
@Configuration
public class ExampleConfig {

    @Autowired
    public ExampleConfig(Environment environment) {
        AbstractEnvironment env = (AbstractEnvironment) environment;
        for (org.springframework.core.env.PropertySource<?> source : env.getPropertySources()) {
            if (source instanceof MapPropertySource mapPropertySource) {
                System.out.println(mapPropertySource.getSource());
            }
        }
    }
}

You can check out the org.springframework.core.env package which contains all of these classes.

So, to answer your first answer more explicitly: No, Spring does not put all properties into a single map. It puts properties from different locations into different PropertySources which are then added to a PropertySources instance.