BAEL-5789 - reinitializing singleton beans in context (#13096)

* BAEL-5789 - reinitializing singleton beans in context

* BAEL-5789 - reinitializing singleton beans in context - changing file path to relative

spring-core-6/src/main/java/com/baeldung/reinitializebean/ReinitializeBeanApp.java

@@ -0,0 +1,11 @@
+package com.baeldung.reinitializebean;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class ReinitializeBeanApp {
+    public static void main(String[] args) {
+        SpringApplication.run(ReinitializeBeanApp.class, args);
+    }
+}

spring-core-6/src/main/java/com/baeldung/reinitializebean/cache/ConfigManager.java

@@ -0,0 +1,51 @@
+package com.baeldung.reinitializebean.cache;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.stereotype.Service;
+
+import javax.annotation.PostConstruct;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Properties;
+
+@Service("ConfigManager")
+public class ConfigManager {
+
+    private static final Log LOG = LogFactory.getLog(ConfigManager.class);
+
+    private Map<String,Object> config;
+
+    private final String filePath;
+
+    public ConfigManager(@Value("${config.file.path}") String filePath) {
+        this.filePath = filePath;
+        initConfigs();
+    }
+
+    private void initConfigs() {
+        Properties properties = new Properties();
+        try {
+            properties.load(Files.newInputStream(Paths.get(filePath)));
+        } catch (IOException e) {
+            LOG.error("Error loading configuration:", e);
+        }
+        config = new HashMap<>();
+        for (Map.Entry<Object, Object> entry : properties.entrySet()) {
+            config.put(String.valueOf(entry.getKey()), entry.getValue());
+        }
+    }
+
+    public Object getConfig(String key) {
+        return config.get(key);
+    }
+
+    public void reinitializeConfig() {
+        initConfigs();
+    }
+
+}

spring-core-6/src/main/java/com/baeldung/reinitializebean/controller/ConfigController.java

@@ -0,0 +1,55 @@
+package com.baeldung.reinitializebean.controller;
+
+import com.baeldung.reinitializebean.cache.ConfigManager;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.beans.factory.support.DefaultSingletonBeanRegistry;
+import org.springframework.context.ApplicationContext;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/config")
+public class ConfigController {
+
+    @Value("${config.file.path}")
+    private String filePath;
+    private final ApplicationContext applicationContext;
+    private final ConfigManager configManager;
+
+    public ConfigController(ApplicationContext applicationContext, ConfigManager configManager) {
+        this.applicationContext = applicationContext;
+        this.configManager = configManager;
+    }
+
+    @GetMapping("/reinitializeConfig")
+    public void reinitializeConfig() {
+        configManager.reinitializeConfig();
+    }
+
+    @GetMapping("/reinitializeBean")
+    public void reinitializeBean() {
+        DefaultSingletonBeanRegistry registry = (DefaultSingletonBeanRegistry) applicationContext.getAutowireCapableBeanFactory();
+        registry.destroySingleton("ConfigManager");
+        registry.registerSingleton("ConfigManager", new ConfigManager(filePath));
+    }
+
+    @GetMapping("/destroyBean")
+    public void destroyBean() {
+        DefaultSingletonBeanRegistry registry = (DefaultSingletonBeanRegistry) applicationContext.getAutowireCapableBeanFactory();
+        registry.destroySingleton("ConfigManager");
+    }
+
+    @GetMapping("/{key}")
+    public Object get(@PathVariable String key) {
+        return configManager.getConfig(key);
+    }
+
+    @GetMapping("/context/{key}")
+    public Object getFromContext(@PathVariable String key) {
+        ConfigManager dynamicConfigManager = applicationContext.getBean(ConfigManager.class);
+        return dynamicConfigManager.getConfig(key);
+    }
+
+}

spring-core-6/src/main/resources/application.properties

@@ -1,4 +1,5 @@
 environment.name=${OS}
 java.home.and.environment=${JAVA_HOME}+${OS}
 not.existing.system.property=${thispropertydoesnotexist}
-baeldung.presentation=${HELLO_BAELDUNG}. Java is installed in the folder: ${JAVA_HOME}
+baeldung.presentation=${HELLO_BAELDUNG}. Java is installed in the folder: ${JAVA_HOME}
+config.file.path=./spring-core-6/src/main/resources/config.properties

spring-core-6/src/main/resources/config.properties

@@ -0,0 +1 @@
+property1=value2