Merge pull request #16029 from abh1navv/BAEL-7521_register_beans

Dynamically register Spring Beans based on properties

spring-di-4/pom.xml

@@ -24,5 +24,15 @@
             <artifactId>spring-boot-starter-test</artifactId>
         </dependency>
     </dependencies>
-
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.springframework.boot</groupId>
+                <artifactId>spring-boot-maven-plugin</artifactId>
+                <configuration>
+                    <mainClass>com.baeldung.registrypostprocessor.RegistryPostProcessorApplication</mainClass>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
 </project>

spring-di-4/src/main/java/com/baeldung/registrypostprocessor/ApiClientConfiguration.java

@@ -0,0 +1,41 @@
+package com.baeldung.registrypostprocessor;
+
+import com.baeldung.registrypostprocessor.bean.ApiClient;
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
+import org.springframework.boot.context.properties.bind.Bindable;
+import org.springframework.boot.context.properties.bind.Binder;
+import org.springframework.core.env.Environment;
+
+import java.util.HashMap;
+import java.util.List;
+
+public class ApiClientConfiguration implements BeanDefinitionRegistryPostProcessor {
+    private static final String API_CLIENT_BEAN_NAME = "apiClient_";
+    List<ApiClient> clients;
+
+    public ApiClientConfiguration(Environment environment) {
+        Binder binder = Binder.get(environment);
+        List<HashMap> properties = binder.bind("api.clients", Bindable.listOf(HashMap.class)).get();
+        clients = properties.stream().map(client -> new ApiClient(String.valueOf(client.get("name")),
+                String.valueOf(client.get("url")), String.valueOf(client.get("key")))).toList();
+    }
+
+    @Override
+    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
+        clients.forEach(client -> {
+            BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(ApiClient.class);
+            builder.addPropertyValue("name", client.getName());
+            builder.addPropertyValue("url", client.getUrl());
+            builder.addPropertyValue("key", client.getKey());
+            registry.registerBeanDefinition(API_CLIENT_BEAN_NAME + client.getName(), builder.getBeanDefinition());
+        });
+    }
+
+    @Override
+    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
+    }
+}

spring-di-4/src/main/java/com/baeldung/registrypostprocessor/RegistryPostProcessorApplication.java

@@ -0,0 +1,22 @@
+package com.baeldung.registrypostprocessor;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.core.env.ConfigurableEnvironment;
+
+
+@SpringBootApplication
+public class RegistryPostProcessorApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(RegistryPostProcessorApplication.class, args);
+    }
+
+    @Bean
+    public ApiClientConfiguration apiClientConfiguration(ConfigurableEnvironment environment) {
+        return new ApiClientConfiguration(environment);
+    }
+
+}
+

spring-di-4/src/main/java/com/baeldung/registrypostprocessor/bean/ApiClient.java

@@ -0,0 +1,45 @@
+package com.baeldung.registrypostprocessor.bean;
+
+public class ApiClient {
+    private String name;
+    private String url;
+    private String key;
+
+    public ApiClient(String name, String url, String key) {
+        this.name = name;
+        this.url = url;
+        this.key = key;
+    }
+
+    public ApiClient() {
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getUrl() {
+        return url;
+    }
+
+    public String getKey() {
+        return key;
+    }
+
+    public String getConnectionProperties() {
+        return "Connecting to " + name + " at " + url;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public void setUrl(String url) {
+        this.url = url;
+    }
+
+    public void setKey(String key) {
+        this.key = key;
+    }
+
+}

spring-di-4/src/main/resources/application.yml

@@ -1 +1,9 @@
-ambiguous-bean: 'A'
+ambiguous-bean: 'A'
+api:
+  clients:
+    - name: example
+      url: https://api.example.com
+      key: 12345
+    - name: anotherexample
+      url: https://api.anotherexample.com
+      key: 67890

spring-di-4/src/test/java/com/baeldung/registrypostprocessor/ApiClientConfigurationUnitTest.java

@@ -0,0 +1,23 @@
+package com.baeldung.registrypostprocessor;
+
+import com.baeldung.registrypostprocessor.bean.ApiClient;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.context.ApplicationContext;
+
+@SpringBootTest(classes = RegistryPostProcessorApplication.class)
+public class ApiClientConfigurationUnitTest {
+    @Autowired
+    private ApplicationContext context;
+
+    @Test
+    void givenBeansRegistered_whenConnect_thenConnected() {
+        ApiClient exampleClient = (ApiClient) context.getBean("apiClient_example");
+        Assertions.assertEquals("Connecting to example at https://api.example.com", exampleClient.getConnectionProperties());
+
+        ApiClient anotherExampleClient = (ApiClient) context.getBean("apiClient_anotherexample");
+        Assertions.assertEquals("Connecting to anotherexample at https://api.anotherexample.com", anotherExampleClient.getConnectionProperties());
+    }
+}

spring-di-4/src/test/resources/application.yml

@@ -1 +1,9 @@
-ambiguous-bean: 'B'
+ambiguous-bean: 'B'
+api:
+  clients:
+    - name: example
+      url: https://api.example.com
+      apiKey: 12345
+    - name: anotherexample
+      url: https://api.anotherexample.com
+      apiKey: 67890