IoC

demo/src/main/java/com/example/demo/speaker/configuration/SpeakerConfiguration.java

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+package com.example.demo.speaker.configuration;
+
+import com.example.demo.speaker.domain.Speaker;
+import com.example.demo.speaker.domain.SpeakerEng;
+import com.example.demo.speaker.domain.SpeakerRus;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class SpeakerConfiguration {
+
+    @Bean(value = "ru")
+    public SpeakerRus createRusSpeaker(){
+        return new SpeakerRus();
+    }
+
+    @Bean(value = "en")
+    public Speaker createEngSpeaker(){
+        return new SpeakerEng();
+    }
+}

demo/src/main/java/com/example/demo/speaker/controller/SpeakerController.java

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+package com.example.demo.speaker.controller;
+
+import com.example.demo.speaker.service.SpeakerService;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class SpeakerController {
+    private final SpeakerService speakerService;
+    public SpeakerController(SpeakerService speakerService){
+        this.speakerService = speakerService;
+    }
+
+    @GetMapping("/hello")
+    public String hello(@RequestParam(defaultValue = "Привет") String name,
+                        @RequestParam(defaultValue = "ru") String lang){
+        return speakerService.say(name, lang);
+    }
+}

demo/src/main/java/com/example/demo/speaker/domain/Speaker.java

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+package com.example.demo.speaker.domain;
+
+public interface Speaker {
+    String say();
+}

demo/src/main/java/com/example/demo/speaker/domain/SpeakerDeu.java

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+package com.example.demo.speaker.domain;
+
+import org.springframework.stereotype.Component;
+
+@Component(value = "de")
+public class SpeakerDeu implements Speaker{
+    @Override
+    public String say(){
+        return "Hallo";
+    }
+}

demo/src/main/java/com/example/demo/speaker/domain/SpeakerEng.java

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+package com.example.demo.speaker.domain;
+
+public class SpeakerEng implements Speaker{
+    @Override
+    public String say() {
+        return "Hello";
+    }
+}

demo/src/main/java/com/example/demo/speaker/domain/SpeakerRus.java

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+package com.example.demo.speaker.domain;
+
+import org.springframework.stereotype.Component;
+
+@Component(value = "ru")
+public class SpeakerRus implements Speaker{
+    @Override
+    public String say(){
+        return "Привет";
+    }
+}

demo/src/main/java/com/example/demo/speaker/service/SpeakerService.java

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+package com.example.demo.speaker.service;
+
+import com.example.demo.speaker.domain.Speaker;
+import org.springframework.context.ApplicationContext;
+import org.springframework.stereotype.Service;
+
+@Service
+public class SpeakerService {
+    private final ApplicationContext applicationContext;
+
+    public SpeakerService(ApplicationContext applicationContext){
+        this.applicationContext = applicationContext;
+    }
+
+    public String say(String name, String lang){
+        final Speaker speaker = (Speaker) applicationContext.getBean(lang);
+        return String.format("Hello %s %s!", speaker.say(), name);
+    }
+}