BAEL-3283 - Refactored the code as per review comments.

spring-mvc-themes/src/main/java/com/baeldung/config/DataSourceConfig.java

@@ -6,7 +6,6 @@ import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
 import org.springframework.orm.jpa.JpaTransactionManager;
-import org.springframework.orm.jpa.JpaVendorAdapter;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
 import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
 import org.springframework.transaction.PlatformTransactionManager;
@@ -29,16 +28,13 @@ public class DataSourceConfig {
         LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
         em.setDataSource(dataSource);
         em.setPackagesToScan("com.baeldung.domain");
-        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
+        em.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
-        em.setJpaVendorAdapter(vendorAdapter);
         return em;
     }
 
     @Bean
     public PlatformTransactionManager transactionManager(EntityManagerFactory emf) {
-        JpaTransactionManager transactionManager = new JpaTransactionManager();
+        return new JpaTransactionManager(emf);
-        transactionManager.setEntityManagerFactory(emf);
-        return transactionManager;
     }
 
     @Bean

spring-mvc-themes/src/main/java/com/baeldung/config/ThemeMVCConfig.java

@@ -39,20 +39,12 @@ public class ThemeMVCConfig implements WebMvcConfigurer {
     }
 
     @Bean
-//    @Profile("cookie")
     public ThemeResolver themeResolver() {
         UserPreferenceThemeResolver themeResolver = new UserPreferenceThemeResolver();
         themeResolver.setDefaultThemeName("light");
         return themeResolver;
     }
 
-//    @Bean
-//    @Profile("database")
-//    public ThemeResolver databaseThemeResolver() {
-//        UserPreferenceThemeResolver themeResolver = new UserPreferenceThemeResolver();
-//        themeResolver.setDefaultThemeName("light");
-//        return themeResolver;
-//    }
 
     @Override
     public void configureViewResolvers(ViewResolverRegistry resolverRegistry) {

spring-mvc-themes/src/main/java/com/baeldung/theme/resolver/UserPreferenceThemeResolver.java

@@ -11,6 +11,7 @@ import org.springframework.web.servlet.ThemeResolver;
 
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
+import java.util.Optional;
 
 public class UserPreferenceThemeResolver implements ThemeResolver {
 
@@ -34,55 +35,40 @@ public class UserPreferenceThemeResolver implements ThemeResolver {
 
     @Override
     public String resolveThemeName(HttpServletRequest request) {
-        String themeName = (String) request.getAttribute(THEME_REQUEST_ATTRIBUTE_NAME);
+        String themeName = findThemeFromRequest(request).orElse(findUserPreferredTheme().orElse(getDefaultThemeName()));
-        if (themeName != null) {
-            return themeName;
-        }
-        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
-
-        if (authentication != null && authentication.isAuthenticated() && isNotAnonymous(authentication)) {
-            User user = (User) authentication.getPrincipal();
-            UserPreference userPreference = userPreferenceRepository.findById(user.getUsername()).orElse(null);
-
-            if (userPreference != null) {
-                themeName = userPreference.getTheme();
-            }
-        }
-
-        // Fall back to default theme.
-        if (themeName == null) {
-            themeName = getDefaultThemeName();
-        }
         request.setAttribute(THEME_REQUEST_ATTRIBUTE_NAME, themeName);
         return themeName;
     }
 
-    private boolean isNotAnonymous(Authentication authentication) {
+    private Optional<String> findUserPreferredTheme() {
-        return !isAnonymous(authentication);
+        Authentication authentication = SecurityContextHolder.getContext()
+            .getAuthentication();
+        UserPreference userPreference = getUserPreference(authentication).orElse(new UserPreference());
+        return Optional.ofNullable(userPreference.getTheme());
     }
 
-    private boolean isAnonymous(Authentication authentication) {
+    private Optional<String> findThemeFromRequest(HttpServletRequest request) {
-        return authentication != null && authentication.getPrincipal() instanceof String && "anonymousUser".equals(authentication.getPrincipal());
+        return Optional.ofNullable((String) request.getAttribute(THEME_REQUEST_ATTRIBUTE_NAME));
+    }
+
+    private Optional<UserPreference> getUserPreference(Authentication authentication) {
+        return isAuthenticated(authentication) ? userPreferenceRepository.findById(((User) authentication.getPrincipal()).getUsername()) : Optional.empty();
+    }
+
+    private boolean isAuthenticated(Authentication authentication) {
+        return authentication != null && authentication.isAuthenticated();
     }
 
     @Override
     public void setThemeName(HttpServletRequest request, HttpServletResponse response, String theme) {
-
+        Authentication authentication = SecurityContextHolder.getContext()
-        Authentication authentication = SecurityContextHolder.getContext().getAuthentication();
+            .getAuthentication();
-        if (authentication != null && authentication.isAuthenticated() && isNotAnonymous(authentication)) {
+        if (isAuthenticated(authentication)) {
             request.setAttribute(THEME_REQUEST_ATTRIBUTE_NAME, theme);
-            User user = (User) authentication.getPrincipal();
+            UserPreference userPreference = getUserPreference(authentication).orElse(new UserPreference());
-
+            userPreference.setUsername(((User) authentication.getPrincipal()).getUsername());
-            UserPreference userPreference = userPreferenceRepository.findById(user.getUsername()).orElse(new UserPreference());
-
-            userPreference.setUsername(user.getUsername());
             userPreference.setTheme(StringUtils.hasText(theme) ? theme : null);
             userPreferenceRepository.save(userPreference);
-
-        }
-
-        if (!StringUtils.hasText(theme)) {
-            request.setAttribute(THEME_REQUEST_ATTRIBUTE_NAME, getDefaultThemeName());
         }
     }
 }

spring-mvc-themes/src/main/resources/db/sql/insert-data.sql

@@ -1,6 +1,6 @@
 insert into users values('john', '$2a$10$cjcbIX/aLe12PpGZ.vQfweLiB7K1QTC5enTk3oD0deCMdtj2Sx.im', 1);
 insert into users values('admin', '$2a$10$cjcbIX/aLe12PpGZ.vQfweLiB7K1QTC5enTk3oD0deCMdtj2Sx.im', 1);
 
-insert into authorities values('sandip', 'USER');
+insert into authorities values('john', 'USER');
 insert into authorities values('admin', 'USER');
 insert into authorities values('admin', 'ADMIN');