BAEL-1800 (#4377)

* BAEL-1800 - Code for http://www.baeldung.com/spring-boot-starters and http://www.baeldung.com/spring-mvc-custom-data-binder

* BAEL-1800 - Code for http://www.baeldung.com/maven-webjars and http://www.baeldung.com/deployable-fat-jar-spring-boot

* BAEL-1800 - Code for http://www.baeldung.com/spring-boot-shutdown

* BAEL-1800 - Code for http://www.baeldung.com/spring-boot-shutdown

* BAEL-1800 - Code for http://www.baeldung.com/spring-boot-dependency-management-custom-parent

spring-boot-ops/src/main/java/com/baeldung/graphql/Author.java

@@ -0,0 +1,31 @@
+package com.baeldung.graphql;
+
+public class Author {
+    private String id;
+    private String name;
+    private String thumbnail;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getThumbnail() {
+        return thumbnail;
+    }
+
+    public void setThumbnail(String thumbnail) {
+        this.thumbnail = thumbnail;
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/AuthorDao.java

@@ -0,0 +1,16 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+import java.util.Optional;
+
+public class AuthorDao {
+    private List<Author> authors;
+
+    public AuthorDao(List<Author> authors) {
+        this.authors = authors;
+    }
+
+    public Optional<Author> getAuthor(String id) {
+        return authors.stream().filter(author -> id.equals(author.getId())).findFirst();
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/AuthorResolver.java

@@ -0,0 +1,17 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+
+import com.coxautodev.graphql.tools.GraphQLResolver;
+
+public class AuthorResolver implements GraphQLResolver<Author> {
+    private PostDao postDao;
+
+    public AuthorResolver(PostDao postDao) {
+        this.postDao = postDao;
+    }
+
+    public List<Post> getPosts(Author author) {
+        return postDao.getAuthorPosts(author.getId());
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/GraphqlConfiguration.java

@@ -0,0 +1,59 @@
+package com.baeldung.graphql;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class GraphqlConfiguration {
+    @Bean
+    public PostDao postDao() {
+        List<Post> posts = new ArrayList<>();
+        for (int postId = 0; postId < 10; ++postId) {
+            for (int authorId = 0; authorId < 10; ++authorId) {
+                Post post = new Post();
+                post.setId("Post" + authorId + postId);
+                post.setTitle("Post " + authorId + ":" + postId);
+                post.setText("Post " + postId + " + by author " + authorId);
+                post.setAuthorId("Author" + authorId);
+                posts.add(post);
+            }
+        }
+        return new PostDao(posts);
+    }
+
+    @Bean
+    public AuthorDao authorDao() {
+        List<Author> authors = new ArrayList<>();
+        for (int authorId = 0; authorId < 10; ++authorId) {
+            Author author = new Author();
+            author.setId("Author" + authorId);
+            author.setName("Author " + authorId);
+            author.setThumbnail("http://example.com/authors/" + authorId);
+            authors.add(author);
+        }
+        return new AuthorDao(authors);
+    }
+
+    @Bean
+    public PostResolver postResolver(AuthorDao authorDao) {
+        return new PostResolver(authorDao);
+    }
+
+    @Bean
+    public AuthorResolver authorResolver(PostDao postDao) {
+        return new AuthorResolver(postDao);
+    }
+
+    @Bean
+    public Query query(PostDao postDao) {
+        return new Query(postDao);
+    }
+
+    @Bean
+    public Mutation mutation(PostDao postDao) {
+        return new Mutation(postDao);
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/Mutation.java

@@ -0,0 +1,25 @@
+package com.baeldung.graphql;
+
+import java.util.UUID;
+
+import com.coxautodev.graphql.tools.GraphQLMutationResolver;
+
+public class Mutation implements GraphQLMutationResolver {
+    private PostDao postDao;
+
+    public Mutation(PostDao postDao) {
+        this.postDao = postDao;
+    }
+
+    public Post writePost(String title, String text, String category, String author) {
+        Post post = new Post();
+        post.setId(UUID.randomUUID().toString());
+        post.setTitle(title);
+        post.setText(text);
+        post.setCategory(category);
+        post.setAuthorId(author);
+        postDao.savePost(post);
+
+        return post;
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/Post.java

@@ -0,0 +1,49 @@
+package com.baeldung.graphql;
+
+public class Post {
+    private String id;
+    private String title;
+    private String text;
+    private String category;
+    private String authorId;
+
+    public String getId() {
+        return id;
+    }
+
+    public void setId(String id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getText() {
+        return text;
+    }
+
+    public void setText(String text) {
+        this.text = text;
+    }
+
+    public String getCategory() {
+        return category;
+    }
+
+    public void setCategory(String category) {
+        this.category = category;
+    }
+
+    public String getAuthorId() {
+        return authorId;
+    }
+
+    public void setAuthorId(String authorId) {
+        this.authorId = authorId;
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/PostDao.java

@@ -0,0 +1,24 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+import java.util.stream.Collectors;
+
+public class PostDao {
+    private List<Post> posts;
+
+    public PostDao(List<Post> posts) {
+        this.posts = posts;
+    }
+
+    public List<Post> getRecentPosts(int count, int offset) {
+        return posts.stream().skip(offset).limit(count).collect(Collectors.toList());
+    }
+
+    public List<Post> getAuthorPosts(String author) {
+        return posts.stream().filter(post -> author.equals(post.getAuthorId())).collect(Collectors.toList());
+    }
+
+    public void savePost(Post post) {
+        posts.add(0, post);
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/PostResolver.java

@@ -0,0 +1,17 @@
+package com.baeldung.graphql;
+
+import java.util.Optional;
+
+import com.coxautodev.graphql.tools.GraphQLResolver;
+
+public class PostResolver implements GraphQLResolver<Post> {
+    private AuthorDao authorDao;
+
+    public PostResolver(AuthorDao authorDao) {
+        this.authorDao = authorDao;
+    }
+
+    public Optional<Author> getAuthor(Post post) {
+        return authorDao.getAuthor(post.getAuthorId());
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/graphql/Query.java

@@ -0,0 +1,17 @@
+package com.baeldung.graphql;
+
+import java.util.List;
+
+import com.coxautodev.graphql.tools.GraphQLQueryResolver;
+
+public class Query implements GraphQLQueryResolver {
+    private PostDao postDao;
+
+    public Query(PostDao postDao) {
+        this.postDao = postDao;
+    }
+
+    public List<Post> recentPosts(int count, int offset) {
+        return postDao.getRecentPosts(count, offset);
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/shutdown/Application.java

@@ -0,0 +1,50 @@
+package com.baeldung.shutdown;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.WebApplicationType;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.context.ApplicationPidFileWriter;
+import org.springframework.context.ConfigurableApplicationContext;
+
+@SpringBootApplication
+public class Application {
+    
+    public static void main(String[] args) {
+
+        SpringApplication.run(Application.class, args);
+//        closeApplication();
+//        exitApplication();
+//        writePID();
+
+    }
+
+    private static void closeApplication() {
+
+        ConfigurableApplicationContext ctx = new SpringApplicationBuilder(Application.class).web(WebApplicationType.NONE).run();
+        System.out.println("Spring Boot application started");
+        ctx.getBean(TerminateBean.class);
+        ctx.close();
+    }
+
+    private static void exitApplication() {
+
+        ConfigurableApplicationContext ctx = new SpringApplicationBuilder(Application.class).web(WebApplicationType.NONE).run();
+
+        int exitCode = SpringApplication.exit(ctx, () -> {
+            // return the error code
+            return 0;
+        });
+
+        System.out.println("Exit Spring Boot");
+
+        System.exit(exitCode);
+    }
+
+    private static void writePID() {
+        SpringApplicationBuilder app = new SpringApplicationBuilder(Application.class).web(WebApplicationType.NONE);
+        app.build().addListeners(new ApplicationPidFileWriter("./bin/shutdown.pid"));
+        app.run();
+    }
+
+}

spring-boot-ops/src/main/java/com/baeldung/shutdown/ShutdownConfig.java

@@ -0,0 +1,15 @@
+package com.baeldung.shutdown;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@ComponentScan(basePackages = "com.baeldung.shutdown")
+public class ShutdownConfig {
+
+    @Bean
+    public TerminateBean getTerminateBean() {
+        return new TerminateBean();
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/shutdown/TerminateBean.java

@@ -0,0 +1,11 @@
+package com.baeldung.shutdown;
+
+import javax.annotation.PreDestroy;
+
+public class TerminateBean {
+
+    @PreDestroy
+    public void onDestroy() throws Exception {
+        System.out.println("Spring Container is destroyed!");
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/shutdown/shutdown/ShutdownController.java

@@ -0,0 +1,25 @@
+package com.baeldung.shutdown.shutdown;
+
+import org.springframework.beans.BeansException;
+import org.springframework.context.ApplicationContext;
+import org.springframework.context.ApplicationContextAware;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class ShutdownController implements ApplicationContextAware {
+    
+    private ApplicationContext context;
+    
+    @PostMapping("/shutdownContext")
+    public void shutdownContext() {
+        ((ConfigurableApplicationContext) context).close();
+    }
+
+    @Override
+    public void setApplicationContext(ApplicationContext ctx) throws BeansException {
+        this.context = ctx;
+        
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/Employee.java

@@ -0,0 +1,37 @@
+package com.baeldung.toggle;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+
+@Entity
+public class Employee {
+
+    @Id
+    private long id;
+    private double salary;
+
+    public Employee() {
+    }
+
+    public Employee(long id, double salary) {
+        this.id = id;
+        this.salary = salary;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public double getSalary() {
+        return salary;
+    }
+
+    public void setSalary(double salary) {
+        this.salary = salary;
+    }
+
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/EmployeeRepository.java

@@ -0,0 +1,7 @@
+package com.baeldung.toggle;
+
+import org.springframework.data.repository.CrudRepository;
+
+public interface EmployeeRepository extends CrudRepository<Employee, Long> {
+
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/FeatureAssociation.java

@@ -0,0 +1,12 @@
+package com.baeldung.toggle;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ ElementType.METHOD, ElementType.TYPE })
+public @interface FeatureAssociation {
+    MyFeatures value();
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/FeaturesAspect.java

@@ -0,0 +1,26 @@
+package com.baeldung.toggle;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.aspectj.lang.ProceedingJoinPoint;
+import org.aspectj.lang.annotation.Around;
+import org.aspectj.lang.annotation.Aspect;
+import org.springframework.stereotype.Component;
+
+@Aspect
+@Component
+public class FeaturesAspect {
+
+    private static final Logger LOG = LogManager.getLogger(FeaturesAspect.class);
+
+    @Around(value = "@within(featureAssociation) || @annotation(featureAssociation)")
+    public Object checkAspect(ProceedingJoinPoint joinPoint, FeatureAssociation featureAssociation) throws Throwable {
+        if (featureAssociation.value().isActive()) {
+            return joinPoint.proceed();
+        } else {
+            LOG.info("Feature " + featureAssociation.value().name() + " is not enabled!");
+            return null;
+        }
+    }
+
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/MyFeatures.java

@@ -0,0 +1,23 @@
+package com.baeldung.toggle;
+
+import org.togglz.core.Feature;
+import org.togglz.core.activation.SystemPropertyActivationStrategy;
+import org.togglz.core.annotation.ActivationParameter;
+import org.togglz.core.annotation.DefaultActivationStrategy;
+import org.togglz.core.annotation.EnabledByDefault;
+import org.togglz.core.annotation.Label;
+import org.togglz.core.context.FeatureContext;
+
+public enum MyFeatures implements Feature {
+
+    @Label("Employee Management Feature")
+    @EnabledByDefault
+    @DefaultActivationStrategy(id = SystemPropertyActivationStrategy.ID, parameters = { @ActivationParameter(name = SystemPropertyActivationStrategy.PARAM_PROPERTY_NAME, value = "employee.feature"),
+            @ActivationParameter(name = SystemPropertyActivationStrategy.PARAM_PROPERTY_VALUE, value = "true") })
+    EMPLOYEE_MANAGEMENT_FEATURE;
+
+    public boolean isActive() {
+        return FeatureContext.getFeatureManager().isActive(this);
+    }
+
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/SalaryController.java

@@ -0,0 +1,20 @@
+package com.baeldung.toggle;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.ResponseBody;
+
+@Controller
+public class SalaryController {
+
+    @Autowired
+    SalaryService salaryService;
+
+    @PostMapping(value = "/increaseSalary")
+    @ResponseBody
+    public void increaseSalary(@RequestParam long id) {
+        salaryService.increaseSalary(id);
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/SalaryService.java

@@ -0,0 +1,19 @@
+package com.baeldung.toggle;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+@Service
+public class SalaryService {
+
+    @Autowired
+    EmployeeRepository employeeRepository;
+
+    @FeatureAssociation(value = MyFeatures.EMPLOYEE_MANAGEMENT_FEATURE)
+    public void increaseSalary(long id) {
+        Employee employee = employeeRepository.findById(id).orElse(null);
+        employee.setSalary(employee.getSalary() + employee.getSalary() * 0.1);
+        employeeRepository.save(employee);
+    }
+
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/ToggleApplication.java

@@ -0,0 +1,15 @@
+package com.baeldung.toggle;
+
+import javax.annotation.security.RolesAllowed;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class ToggleApplication {
+    @RolesAllowed("*")
+    public static void main(String[] args) {
+        System.setProperty("security.basic.enabled", "false");
+        SpringApplication.run(ToggleApplication.class, args);
+    }
+}

spring-boot-ops/src/main/java/com/baeldung/toggle/ToggleConfiguration.java

@@ -0,0 +1,20 @@
+package com.baeldung.toggle;
+
+import org.springframework.boot.autoconfigure.domain.EntityScan;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
+import org.togglz.core.manager.EnumBasedFeatureProvider;
+import org.togglz.core.spi.FeatureProvider;
+
+@Configuration
+@EnableJpaRepositories("com.baeldung.toggle")
+@EntityScan("com.baeldung.toggle")
+public class ToggleConfiguration {
+
+    @Bean
+    public FeatureProvider featureProvider() {
+        return new EnumBasedFeatureProvider(MyFeatures.class);
+    }
+
+}

spring-boot-ops/src/main/java/com/baeldung/webjar/TestController.java

@@ -0,0 +1,15 @@
+package com.baeldung.webjar;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.GetMapping;
+
+@Controller
+public class TestController {
+
+    @GetMapping(value = "/")
+    public String welcome(Model model) {
+        return "index";
+    }
+
+}

spring-boot-ops/src/main/java/com/baeldung/webjar/WebjarsdemoApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.webjar;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class WebjarsdemoApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(WebjarsdemoApplication.class, args);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/Application.java

@@ -0,0 +1,14 @@
+package org.baeldung.boot;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.ApplicationContext;
+
+@SpringBootApplication
+public class Application {
+    private static ApplicationContext applicationContext;
+
+    public static void main(String[] args) {
+        applicationContext = SpringApplication.run(Application.class, args);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/config/WebConfig.java

@@ -0,0 +1,28 @@
+package org.baeldung.boot.config;
+
+import org.baeldung.boot.converter.GenericBigDecimalConverter;
+import org.baeldung.boot.converter.StringToEmployeeConverter;
+import org.baeldung.boot.converter.StringToEnumConverterFactory;
+import org.baeldung.boot.web.resolver.HeaderVersionArgumentResolver;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.format.FormatterRegistry;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
+
+import java.util.List;
+
+@Configuration
+public class WebConfig implements WebMvcConfigurer {
+
+    @Override
+    public void addArgumentResolvers(final List<HandlerMethodArgumentResolver> argumentResolvers) {
+        argumentResolvers.add(new HeaderVersionArgumentResolver());
+    }
+
+    @Override
+    public void addFormatters(FormatterRegistry registry) {
+        registry.addConverter(new StringToEmployeeConverter());
+        registry.addConverterFactory(new StringToEnumConverterFactory());
+        registry.addConverter(new GenericBigDecimalConverter());
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/controller/GenericEntityController.java

@@ -0,0 +1,58 @@
+package org.baeldung.boot.controller;
+
+import org.baeldung.boot.domain.GenericEntity;
+import org.baeldung.boot.domain.Modes;
+import org.baeldung.boot.web.resolver.Version;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.time.LocalDateTime;
+import java.util.ArrayList;
+import java.util.List;
+
+@RestController
+public class GenericEntityController {
+    private List<GenericEntity> entityList = new ArrayList<>();
+
+    {
+        entityList.add(new GenericEntity(1l, "entity_1"));
+        entityList.add(new GenericEntity(2l, "entity_2"));
+        entityList.add(new GenericEntity(3l, "entity_3"));
+        entityList.add(new GenericEntity(4l, "entity_4"));
+    }
+
+    @GetMapping("/entity/all")
+    public List<GenericEntity> findAll() {
+        return entityList;
+    }
+
+    @PostMapping("/entity")
+    public GenericEntity addEntity(GenericEntity entity) {
+        entityList.add(entity);
+        return entity;
+    }
+
+    @GetMapping("/entity/findby/{id}")
+    public GenericEntity findById(@PathVariable Long id) {
+        return entityList.stream().filter(entity -> entity.getId().equals(id)).findFirst().get();
+    }
+
+    @GetMapping("/entity/findbydate/{date}")
+    public GenericEntity findByDate(@PathVariable("date") LocalDateTime date) {
+        return entityList.stream().findFirst().get();
+    }
+
+    @GetMapping("/entity/findbymode/{mode}")
+    public GenericEntity findByEnum(@PathVariable("mode") Modes mode) {
+        return entityList.stream().findFirst().get();
+    }
+
+    @GetMapping("/entity/findbyversion")
+    public ResponseEntity findByVersion(@Version String version) {
+        return version != null ? new ResponseEntity(entityList.stream().findFirst().get(), HttpStatus.OK) : new ResponseEntity(HttpStatus.NOT_FOUND);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/converter/GenericBigDecimalConverter.java

@@ -0,0 +1,34 @@
+package org.baeldung.boot.converter;
+
+import com.google.common.collect.ImmutableSet;
+import org.springframework.core.convert.TypeDescriptor;
+import org.springframework.core.convert.converter.GenericConverter;
+
+import java.math.BigDecimal;
+import java.util.Set;
+
+public class GenericBigDecimalConverter implements GenericConverter {
+    @Override
+    public Set<ConvertiblePair> getConvertibleTypes() {
+
+        ConvertiblePair[] pairs = new ConvertiblePair[] { new ConvertiblePair(Number.class, BigDecimal.class), new ConvertiblePair(String.class, BigDecimal.class) };
+
+        return ImmutableSet.copyOf(pairs);
+    }
+
+    @Override
+    public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+        if (sourceType.getType() == BigDecimal.class) {
+            return source;
+        }
+
+        if (sourceType.getType() == String.class) {
+            String number = (String) source;
+            return new BigDecimal(number);
+        } else {
+            Number number = (Number) source;
+            BigDecimal converted = new BigDecimal(number.doubleValue());
+            return converted.setScale(2, BigDecimal.ROUND_HALF_EVEN);
+        }
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/converter/StringToEmployeeConverter.java

@@ -0,0 +1,13 @@
+package org.baeldung.boot.converter;
+
+import com.baeldung.toggle.Employee;
+import org.springframework.core.convert.converter.Converter;
+
+public class StringToEmployeeConverter implements Converter<String, Employee> {
+
+    @Override
+    public Employee convert(String from) {
+        String[] data = from.split(",");
+        return new Employee(Long.parseLong(data[0]), Double.parseDouble(data[1]));
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/converter/StringToEnumConverterFactory.java

@@ -0,0 +1,27 @@
+package org.baeldung.boot.converter;
+
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.core.convert.converter.ConverterFactory;
+import org.springframework.stereotype.Component;
+
+@Component
+public class StringToEnumConverterFactory implements ConverterFactory<String, Enum> {
+
+    private static class StringToEnumConverter<T extends Enum> implements Converter<String, T> {
+
+        private Class<T> enumType;
+
+        public StringToEnumConverter(Class<T> enumType) {
+            this.enumType = enumType;
+        }
+
+        public T convert(String source) {
+            return (T) Enum.valueOf(this.enumType, source.trim());
+        }
+    }
+
+    @Override
+    public <T extends Enum> Converter<String, T> getConverter(final Class<T> targetType) {
+        return new StringToEnumConverter(targetType);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/converter/StringToLocalDateTimeConverter.java

@@ -0,0 +1,16 @@
+package org.baeldung.boot.converter;
+
+import org.springframework.core.convert.converter.Converter;
+import org.springframework.stereotype.Component;
+
+import java.time.LocalDateTime;
+import java.time.format.DateTimeFormatter;
+
+@Component
+public class StringToLocalDateTimeConverter implements Converter<String, LocalDateTime> {
+
+    @Override
+    public LocalDateTime convert(final String source) {
+        return LocalDateTime.parse(source, DateTimeFormatter.ISO_LOCAL_DATE_TIME);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/converter/controller/StringToEmployeeConverterController.java

@@ -0,0 +1,15 @@
+package org.baeldung.boot.converter.controller;
+
+import com.baeldung.toggle.Employee;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+@RestController
+@RequestMapping("/string-to-employee")
+public class StringToEmployeeConverterController {
+
+    @GetMapping
+    public ResponseEntity<Object> getStringToEmployee(@RequestParam("employee") Employee employee) {
+        return ResponseEntity.ok(employee);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/domain/GenericEntity.java

@@ -0,0 +1,42 @@
+package org.baeldung.boot.domain;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Entity
+public class GenericEntity {
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+    private String value;
+
+    public GenericEntity() {
+    }
+
+    public GenericEntity(String value) {
+        this.value = value;
+    }
+
+    public GenericEntity(Long id, String value) {
+        this.id = id;
+        this.value = value;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getValue() {
+        return value;
+    }
+
+    public void setValue(String value) {
+        this.value = value;
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/domain/Modes.java

@@ -0,0 +1,6 @@
+package org.baeldung.boot.domain;
+
+public enum Modes {
+
+    ALPHA, BETA;
+}

spring-boot-ops/src/main/java/org/baeldung/boot/repository/GenericEntityRepository.java

@@ -0,0 +1,7 @@
+package org.baeldung.boot.repository;
+
+import org.baeldung.boot.domain.GenericEntity;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface GenericEntityRepository extends JpaRepository<GenericEntity, Long> {
+}

spring-boot-ops/src/main/java/org/baeldung/boot/web/resolver/HeaderVersionArgumentResolver.java

@@ -0,0 +1,26 @@
+package org.baeldung.boot.web.resolver;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.stereotype.Component;
+import org.springframework.web.bind.support.WebDataBinderFactory;
+import org.springframework.web.context.request.NativeWebRequest;
+import org.springframework.web.method.support.HandlerMethodArgumentResolver;
+import org.springframework.web.method.support.ModelAndViewContainer;
+
+import javax.servlet.http.HttpServletRequest;
+
+@Component
+public class HeaderVersionArgumentResolver implements HandlerMethodArgumentResolver {
+
+    @Override
+    public boolean supportsParameter(final MethodParameter methodParameter) {
+        return methodParameter.getParameterAnnotation(Version.class) != null;
+    }
+
+    @Override
+    public Object resolveArgument(final MethodParameter methodParameter, final ModelAndViewContainer modelAndViewContainer, final NativeWebRequest nativeWebRequest, final WebDataBinderFactory webDataBinderFactory) throws Exception {
+        HttpServletRequest request = (HttpServletRequest) nativeWebRequest.getNativeRequest();
+
+        return request.getHeader("Version");
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/boot/web/resolver/Version.java

@@ -0,0 +1,11 @@
+package org.baeldung.boot.web.resolver;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.PARAMETER)
+public @interface Version {
+}

spring-boot-ops/src/main/java/org/baeldung/demo/DemoApplication.java

@@ -0,0 +1,18 @@
+package org.baeldung.demo;
+
+import com.baeldung.graphql.GraphqlConfiguration;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+import org.springframework.context.annotation.Import;
+
+@SpringBootApplication
+@Import(GraphqlConfiguration.class)
+public class DemoApplication {
+
+    public static void main(String[] args) {
+        System.setProperty("spring.config.name", "demo");
+        SpringApplication.run(DemoApplication.class, args);
+    }
+
+}

spring-boot-ops/src/main/java/org/baeldung/demo/boottest/Employee.java

@@ -0,0 +1,43 @@
+package org.baeldung.demo.boottest;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.Table;
+import javax.validation.constraints.Size;
+
+@Entity
+@Table(name = "person")
+public class Employee {
+
+    public Employee() {
+    }
+
+    public Employee(String name) {
+        this.name = name;
+    }
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private Long id;
+
+    @Size(min = 3, max = 20)
+    private String name;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/demo/boottest/EmployeeRepository.java

@@ -0,0 +1,17 @@
+package org.baeldung.demo.boottest;
+
+import java.util.List;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+import org.springframework.transaction.annotation.Transactional;
+
+@Repository
+@Transactional
+public interface EmployeeRepository extends JpaRepository<Employee, Long> {
+
+    public Employee findByName(String name);
+
+    public List<Employee> findAll();
+
+}

spring-boot-ops/src/main/java/org/baeldung/demo/boottest/EmployeeRestController.java

@@ -0,0 +1,33 @@
+package org.baeldung.demo.boottest;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/api")
+public class EmployeeRestController {
+
+    @Autowired
+    private EmployeeService employeeService;
+
+    @PostMapping("/employees")
+    public ResponseEntity<Employee> createEmployee(@RequestBody Employee employee) {
+        HttpStatus status = HttpStatus.CREATED;
+        Employee saved = employeeService.save(employee);
+        return new ResponseEntity<>(saved, status);
+    }
+
+    @GetMapping("/employees")
+    public List<Employee> getAllEmployees() {
+        return employeeService.getAllEmployees();
+    }
+
+}

spring-boot-ops/src/main/java/org/baeldung/demo/boottest/EmployeeService.java

@@ -0,0 +1,16 @@
+package org.baeldung.demo.boottest;
+
+import java.util.List;
+
+public interface EmployeeService {
+
+    public Employee getEmployeeById(Long id);
+
+    public Employee getEmployeeByName(String name);
+
+    public List<Employee> getAllEmployees();
+
+    public boolean exists(String email);
+
+    public Employee save(Employee employee);
+}

spring-boot-ops/src/main/java/org/baeldung/demo/boottest/EmployeeServiceImpl.java

@@ -0,0 +1,43 @@
+package org.baeldung.demo.boottest;
+
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@Transactional
+public class EmployeeServiceImpl implements EmployeeService {
+
+    @Autowired
+    private EmployeeRepository employeeRepository;
+
+    @Override
+    public Employee getEmployeeById(Long id) {
+        return employeeRepository.findById(id).orElse(null);
+    }
+
+    @Override
+    public Employee getEmployeeByName(String name) {
+        return employeeRepository.findByName(name);
+    }
+
+    @Override
+    public boolean exists(String name) {
+        if (employeeRepository.findByName(name) != null) {
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public Employee save(Employee employee) {
+        return employeeRepository.save(employee);
+    }
+
+    @Override
+    public List<Employee> getAllEmployees() {
+        return employeeRepository.findAll();
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/demo/components/FooService.java

@@ -0,0 +1,21 @@
+package org.baeldung.demo.components;
+
+import org.baeldung.demo.model.Foo;
+import org.baeldung.demo.repository.FooRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+@Component
+public class FooService {
+
+    @Autowired
+    private FooRepository fooRepository;
+
+    public Foo getFooWithId(Integer id) throws Exception {
+        return fooRepository.findById(id).orElse(null);
+    }
+
+    public Foo getFooWithName(String name) {
+        return fooRepository.findByName(name);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/demo/exceptions/CommonException.java

@@ -0,0 +1,13 @@
+package org.baeldung.demo.exceptions;
+
+public class CommonException extends RuntimeException {
+
+    /**
+     * 
+     */
+    private static final long serialVersionUID = 3080004140659213332L;
+
+    public CommonException(String message) {
+        super(message);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/demo/exceptions/FooNotFoundException.java

@@ -0,0 +1,13 @@
+package org.baeldung.demo.exceptions;
+
+public class FooNotFoundException extends RuntimeException {
+
+    /**
+     * 
+     */
+    private static final long serialVersionUID = 9042200028456133589L;
+
+    public FooNotFoundException(String message) {
+        super(message);
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/demo/model/Foo.java

@@ -0,0 +1,45 @@
+package org.baeldung.demo.model;
+
+import java.io.Serializable;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+@Entity
+public class Foo implements Serializable {
+    private static final long serialVersionUID = 1L;
+    @Id
+    @GeneratedValue
+    private Integer id;
+    private String name;
+
+    public Foo() {
+    }
+
+    public Foo(String name) {
+        this.name = name;
+    }
+
+    public Foo(Integer id, String name) {
+        super();
+        this.id = id;
+        this.name = name;
+    }
+
+    public Integer getId() {
+        return id;
+    }
+
+    public void setId(Integer id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

spring-boot-ops/src/main/java/org/baeldung/demo/repository/FooRepository.java

@@ -0,0 +1,8 @@
+package org.baeldung.demo.repository;
+
+import org.baeldung.demo.model.Foo;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface FooRepository extends JpaRepository<Foo, Integer> {
+    public Foo findByName(String name);
+}

spring-boot-ops/src/main/java/org/baeldung/demo/service/FooController.java

@@ -0,0 +1,26 @@
+package org.baeldung.demo.service;
+
+import org.baeldung.demo.components.FooService;
+import org.baeldung.demo.model.Foo;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestParam;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class FooController {
+
+    @Autowired
+    private FooService fooService;
+
+    @GetMapping("/{id}")
+    public Foo getFooWithId(@PathVariable Integer id) throws Exception {
+        return fooService.getFooWithId(id);
+    }
+
+    @GetMapping("/")
+    public Foo getFooWithName(@RequestParam String name) throws Exception {
+        return fooService.getFooWithName(name);
+    }
+}