Merge pull request #10 from bobocode-projects/GP-67_new_hello-spring-framework_(for_web)_exercise_MAIN

Gp 67 new hello spring framework (for web) exercise main

Author: tboychuk

3-0-spring-framework/3-0-0-hello-spring-framework/README.MD

@@ -0,0 +1,21 @@
+# <img src="https://raw.githubusercontent.com/bobocode-projects/resources/master/image/logo_transparent_background.png" height=50/>Hello ApplicationContext exercise :muscle:
+Improve your *Spring ApplicationContext* Java configuration skills
+### Task
+The task is to **configure `ApplicationContext`** that contains `AccountService` bean, `AccountDao` bean 
+and `TestDataGenerator` bean. Your job is to follow the instructions in the *todo* section and **implement 
+a proper configuration.**  
+
+To verify your configuration, run `AppConfigTest.java`
+
+ 
+### Pre-conditions :heavy_exclamation_mark:
+You're supposed to be familiar with *Spring IoC* and *Dependency injection*
+
+### How to start :question:
+* Just clone the repository and start implementing the **todo** section, verify your changes by running tests
+* If you don't have enough knowledge about this domain, check out the [links below](#related-materials-information_source)
+* Don't worry if you got stuck, checkout the **exercise/completed** branch and see the final implementation
+ 
+### Related materials :information_source:
+ * [Spring IoC basics tutorial](https://github.com/boy4uck/spring-framework-tutorial/tree/master/spring-framework-ioc-basics)<img src="https://raw.githubusercontent.com/bobocode-projects/resources/master/image/logo_transparent_background.png" height=20/>
+

3-0-spring-framework/3-0-0-hello-spring-framework/pom.xml

@@ -0,0 +1,49 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <artifactId>3-0-spring-framework</artifactId>
+        <groupId>com.bobocode</groupId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>3-0-0-hello-spring-framework</artifactId>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-context</artifactId>
+            <version>5.2.12.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-test</artifactId>
+            <version>5.2.12.RELEASE</version>
+        </dependency>
+        <dependency>
+            <groupId>com.bobocode</groupId>
+            <artifactId>spring-framework-exercises-util</artifactId>
+            <version>1.0-SNAPSHOT</version>
+        </dependency>
+        <dependency>
+            <groupId>org.hamcrest</groupId>
+            <artifactId>hamcrest-all</artifactId>
+            <version>1.3</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-simple</artifactId>
+            <version>1.7.24</version>
+        </dependency>
+        <dependency>
+            <groupId>com.bobocode</groupId>
+            <artifactId>spring-framework-exercises-model</artifactId>
+            <version>1.0-SNAPSHOT</version>
+            <scope>compile</scope>
+        </dependency>
+    </dependencies>
+
+</project>

3-0-spring-framework/3-0-0-hello-spring-framework/src/main/java/com/bobocode/config/ApplicationConfig.java

@@ -0,0 +1,30 @@
+package com.bobocode.config;
+
+import com.bobocode.TestDataGenerator;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Import;
+import org.springframework.context.annotation.ImportResource;
+import org.springframework.stereotype.Component;
+
+/**
+ * This class specify application context configuration. Basically, it's all about which instances of which classes
+ * should be created and registered in the context. An instance that is registered in the context is called 'bean'.
+ * <p>
+ * To tell the container, which bean should be created, you could either specify packages to scan using @{@link ComponentScan},
+ * or declare your own beans using @{@link Bean}. When you use @{@link ComponentScan} the container will discover
+ * specified package and its sub-folders, to find all classes marked @{@link Component}.
+ * <p>
+ * If you want to import other configs from Java class or XML file, you could use @{@link Import}
+ * and @{@link ImportResource} accordingly
+ * <p>
+ * todo 1: make this class a Spring configuration class
+ * todo 2: enable component scanning for dao and service packages
+ * todo 3: provide explicit configuration for a bean of type {@link TestDataGenerator} with name "dataGenerator" in this class.
+ * hint: use method creation approach with @Bean annotation;
+ * todo 4: Don't specify bean name "dataGenerator" explicitly
+ */
+
+public class ApplicationConfig {
+
+}

3-0-spring-framework/3-0-0-hello-spring-framework/src/main/java/com/bobocode/dao/AccountDao.java

@@ -0,0 +1,12 @@
+package com.bobocode.dao;
+
+import com.bobocode.model.Account;
+
+import java.util.List;
+
+/**
+ * Defines an API for {@link Account} data access object (DAO).
+ */
+public interface AccountDao {
+    List<Account> findAll();
+}

3-0-spring-framework/3-0-0-hello-spring-framework/src/main/java/com/bobocode/dao/FakeAccountDao.java

@@ -0,0 +1,34 @@
+package com.bobocode.dao;
+
+import com.bobocode.TestDataGenerator;
+import com.bobocode.model.Account;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Component;
+
+import java.util.List;
+import java.util.stream.Stream;
+
+import static java.util.stream.Collectors.toList;
+
+/**
+ * This class should be marked with @{@link Component}, thus Spring container will create an instance
+ * of {@link FakeAccountDao} class, and will register it the context.
+ * <p>
+ * todo: configure this class as Spring component with bean name "accountDao"
+ * todo: use explicit (with {@link Autowired} annotation) constructor-based dependency injection for specific bean
+ */
+
+public class FakeAccountDao implements AccountDao {
+    private List<Account> accounts;
+
+    public FakeAccountDao(TestDataGenerator testDataGenerator) {
+        this.accounts = Stream.generate(testDataGenerator::generateAccount)
+                .limit(20)
+                .collect(toList());
+    }
+
+    @Override
+    public List<Account> findAll() {
+        return accounts;
+    }
+}

3-0-spring-framework/3-0-0-hello-spring-framework/src/main/java/com/bobocode/service/AccountService.java

@@ -0,0 +1,29 @@
+package com.bobocode.service;
+
+import com.bobocode.dao.AccountDao;
+import com.bobocode.model.Account;
+
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * Provides service API for {@link Account}.
+ * <p>
+ * todo: configure {@link AccountService} bean implicitly using special annotation for service classes
+ * todo: use implicit constructor-based dependency injection (don't use {@link org.springframework.beans.factory.annotation.Autowired})
+ */
+
+public class AccountService {
+    private final AccountDao accountDao;
+
+    public AccountService(AccountDao accountDao) {
+        this.accountDao = accountDao;
+    }
+
+    public Account findRichestAccount() {
+        List<Account> accounts = accountDao.findAll();
+        return accounts.stream()
+                .max(Comparator.comparing(Account::getBalance))
+                .get();
+    }
+}

3-0-spring-framework/3-0-0-hello-spring-framework/src/test/java/com/bobocode/ApplicationConfigTest.java

@@ -0,0 +1,120 @@
+package com.bobocode;
+
+import com.bobocode.config.ApplicationConfig;
+import com.bobocode.dao.AccountDao;
+import com.bobocode.dao.FakeAccountDao;
+import com.bobocode.service.AccountService;
+import org.junit.jupiter.api.*;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ComponentScan;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.stereotype.Component;
+import org.springframework.stereotype.Service;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
+public class ApplicationConfigTest {
+
+    @Test
+    @Order(1)
+    @DisplayName("Config class is marked as @Configuration")
+    void configClassIsMarkedAsConfiguration() {
+        Configuration configuration = ApplicationConfig.class.getAnnotation(Configuration.class);
+
+        assertNotNull(configuration);
+    }
+
+    @Test
+    @Order(2)
+    @DisplayName("@ComponentScan is enabled")
+    void componentScanIsEnabled() {
+        ComponentScan componentScan = ApplicationConfig.class.getAnnotation(ComponentScan.class);
+
+        assertNotNull(componentScan);
+    }
+
+    @Test
+    @Order(3)
+    @DisplayName("@ComponentScan configured for \"dao\" and \"service\" packages")
+    void componentScanPackagesAreSpecified() {
+        ComponentScan componentScan = ApplicationConfig.class.getAnnotation(ComponentScan.class);
+        String[] packages = componentScan.basePackages();
+        if (packages.length == 0) {
+            packages = componentScan.value();
+        }
+        assertThat(packages).containsExactlyInAnyOrder("com.bobocode.dao", "com.bobocode.service");
+    }
+
+    @Test
+    @Order(4)
+    @DisplayName("DataGenerator bean is configured in method marked with @Bean")
+    void dataGeneratorBeanIsConfiguredExplicitly() {
+        Method[] methods = ApplicationConfig.class.getMethods();
+        Method testDataGeneratorBeanMethod = findTestDataGeneratorBeanMethod(methods);
+
+        assertNotNull(testDataGeneratorBeanMethod);
+    }
+
+    @Test
+    @Order(5)
+    @DisplayName("DataGenerator bean name is not specified explicitly")
+    void dataGeneratorBeanNameIsNotSpecifiedExplicitly() {
+        Method[] methods = ApplicationConfig.class.getMethods();
+        Method testDataGeneratorBeanMethod = findTestDataGeneratorBeanMethod(methods);
+        Bean bean = testDataGeneratorBeanMethod.getDeclaredAnnotation(Bean.class);
+
+        assertThat(bean.name().length).isEqualTo(0);
+        assertThat(bean.value().length).isEqualTo(0);
+    }
+
+    @Test
+    @Order(6)
+    @DisplayName("FakeAccountDao is configured as @Component")
+    void fakeAccountDaoIsConfiguredAsComponent() {
+        Component component = FakeAccountDao.class.getAnnotation(Component.class);
+
+        assertNotNull(component);
+    }
+
+    @Test
+    @Order(7)
+    @DisplayName("AccountService is configured as @Service")
+    void accountServiceIsConfiguredAsService() {
+        Service service = AccountService.class.getAnnotation(Service.class);
+
+        assertNotNull(service);
+    }
+
+    @Test
+    @Order(8)
+    @DisplayName("AccountService bean name is not specified explicitly")
+    void accountServiceBeanNameIsNotSpecifiedExplicitly() {
+        Service service = AccountService.class.getAnnotation(Service.class);
+
+        assertThat(service.value()).isEqualTo("");
+    }
+
+    @Test
+    @Order(9)
+    @DisplayName("AccountService doesn't use @Autowired")
+    void accountServiceDoesNotUseAutowired() throws NoSuchMethodException {
+        Annotation[] annotations = AccountService.class.getConstructor(AccountDao.class).getDeclaredAnnotations();
+
+        assertThat(annotations.length).isEqualTo(0);
+    }
+
+    private Method findTestDataGeneratorBeanMethod(Method[] methods) {
+        for (Method method : methods) {
+            if (method.getReturnType().equals(TestDataGenerator.class)
+                    && method.getDeclaredAnnotation(Bean.class) != null) {
+                return method;
+            }
+        }
+        return null;
+    }
+}