BAEL-4087: Inject a Map from a yaml file with Spring (#9560)

* Add server.yml

* Add MapFromYamlApplication.java

* Add YamlPropertySourceFactory.java

* Add ServerProperties.java

* Add MapFromYamlApplicationTests.java

* last commit

Co-authored-by: azhwani <>

spring-boot-modules/spring-boot-properties-2/src/main/java/com/baeldung/properties/yamlmap/MapFromYaml.java

@@ -0,0 +1,13 @@
+package com.baeldung.properties.yamlmap;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class MapFromYaml {
+
+    public static void main(String[] args) {
+        SpringApplication.run(MapFromYaml.class, args);
+    }
+
+}

spring-boot-modules/spring-boot-properties-2/src/main/java/com/baeldung/properties/yamlmap/factory/YamlPropertySourceFactory.java

@@ -0,0 +1,25 @@
+package com.baeldung.properties.yamlmap.factory;
+
+import org.springframework.beans.factory.config.YamlPropertiesFactoryBean;
+import org.springframework.core.env.PropertiesPropertySource;
+import org.springframework.core.env.PropertySource;
+import org.springframework.core.io.support.EncodedResource;
+import org.springframework.core.io.support.PropertySourceFactory;
+
+import java.io.IOException;
+import java.util.Properties;
+
+public class YamlPropertySourceFactory implements PropertySourceFactory {
+
+    @Override
+    public PropertySource<?> createPropertySource(String name, EncodedResource encodedResource) throws IOException {
+        YamlPropertiesFactoryBean factory = new YamlPropertiesFactoryBean();
+        factory.setResources(encodedResource.getResource());
+
+        Properties properties = factory.getObject();
+
+        return new PropertiesPropertySource(encodedResource.getResource()
+            .getFilename(), properties);
+    }
+
+}

spring-boot-modules/spring-boot-properties-2/src/main/java/com/baeldung/properties/yamlmap/pojo/ServerProperties.java

@@ -0,0 +1,66 @@
+package com.baeldung.properties.yamlmap.pojo;
+
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.context.annotation.PropertySource;
+import org.springframework.stereotype.Component;
+
+import com.baeldung.properties.yamlmap.factory.YamlPropertySourceFactory;
+
+@Component
+@PropertySource(value = "classpath:server.yml", factory = YamlPropertySourceFactory.class)
+@ConfigurationProperties(prefix = "server")
+public class ServerProperties {
+
+    private Map<String, String> application;
+    private Map<String, List<String>> config;
+    private Map<String, Credential> users;
+
+    public Map<String, String> getApplication() {
+        return application;
+    }
+
+    public void setApplication(Map<String, String> application) {
+        this.application = application;
+    }
+
+    public Map<String, List<String>> getConfig() {
+        return config;
+    }
+
+    public void setConfig(Map<String, List<String>> config) {
+        this.config = config;
+    }
+
+    public Map<String, Credential> getUsers() {
+        return users;
+    }
+
+    public void setUsers(Map<String, Credential> users) {
+        this.users = users;
+    }
+
+    public static class Credential {
+
+        private String username;
+        private String password;
+
+        public String getUsername() {
+            return username;
+        }
+
+        public void setUsername(String username) {
+            this.username = username;
+        }
+
+        public String getPassword() {
+            return password;
+        }
+
+        public void setPassword(String password) {
+            this.password = password;
+        }
+    }
+}

spring-boot-modules/spring-boot-properties-2/src/main/resources/server.yml

@@ -0,0 +1,22 @@
+server:
+  application:
+    name: InjectMapFromYAML
+    url: http://injectmapfromyaml.dev
+    description: How To Inject a map from a YAML File in Spring Boot
+  config:
+    ips:
+      - 10.10.10.10
+      - 10.10.10.11
+      - 10.10.10.12
+      - 10.10.10.13
+    filesystem:
+      - /dev/root
+      - /dev/md2
+      - /dev/md4
+  users: 
+    root:
+      username: root
+      password: rootpass
+    guest:
+      username: guest
+      password: guestpass

spring-boot-modules/spring-boot-properties-2/src/test/java/com/baeldung/properties/yamlmap/MapFromYamlIntegrationTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.properties.yamlmap;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import com.baeldung.properties.yamlmap.pojo.ServerProperties;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest
+class MapFromYamlIntegrationTest {
+
+    @Autowired
+    private ServerProperties serverProperties;
+
+    @Test
+    public void whenYamlFileProvidedThenInjectSimpleMap() {
+
+        assertThat(serverProperties.getApplication()).containsOnlyKeys("name", "url", "description");
+
+        assertThat(serverProperties.getApplication()
+            .get("name")).isEqualTo("InjectMapFromYAML");
+    }
+
+    @Test
+    public void whenYamlFileProvidedThenInjectComplexMap() {
+
+        assertThat(serverProperties.getConfig()).hasSize(2);
+
+        assertThat(serverProperties.getConfig()
+            .get("ips")
+            .get(0)).isEqualTo("10.10.10.10");
+
+        assertThat(serverProperties.getUsers()
+            .get("root")
+            .getUsername()).isEqualTo("root");
+    }
+
+}