Spring Framework Petclinic sample application
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The Spring Framework Petclinic is a sample application demonstrating the use of Spring's core functionalities for building database-oriented applications, utilizing features like IoC, MVC, JPA, and transaction management. It offers multiple configurations with support for various database technologies and includes options for testing and monitoring through AOP. Several versions and forks exist, showcasing different architectures and technologies within the Spring ecosystem.
Spring Framework Petclinic sample application
- 2. Spring Petclinic Sample application designed to show how the Spring application frameworks can be used to build simple, but powerful database-oriented applications Demonstrate the use of Spring's core functionality: JavaBeans based application configuration using Inversion of Control (IoC) Model View Controller (MVC) web Presentation Layer Practical database access through JDBC, Java Persistence API (JPA) or Spring Data JPA Application monitoring based on JMX Declarative Transaction Management using AOP Data Validation that supports but is not dependent on the Presentation Layer Exists many versions (forks) of the Spring Petclinic sample application
- 3. Spring Framework Petclinic https://github.com/spring-petclinic/spring-framework-petclinic Fork of the « canonical » implementation of Spring Petclinic Maintain a Petclinic version with a plain old Spring Framework configuration and with a 3-layer architecture
- 4. 3 Spring profiles JDBC JPA (default) Spring Data JPA Repository Service @Cacheable @Transactional Controller Bean Validation Spring @MVC annotations Views Bootstrap (CSS) JSP with custom tags custom LESS webjars Software Layers
- 5. Domain Model
- 6. Data Access VisitRepository JdbcVisit RepositoryImpl JpaVisit RepositoryImpl SpringData VisitRepository findByPetId: 16 lines of code findByPetId: 3 (short) lines of code findByPetId: 0 lines (interface declaration is enough based on naming conventions) In order to select which implementation should be used : 1. select the appropriate bean profile inside PetclinicInitializer (jdbc, jpa or spring-data-jpa) 2. or use the -Dspring.profiles.active=jdbc VM option
- 7. Database # Properties that control the population of schema and data for a new data source jdbc.initLocation=classpath:db/${db.script}/initDB.sql jdbc.dataLocation=classpath:db/${db.script}/populateDB.sql Supports HSQLDB (default), MySQL, PostgreSQL Connections parameters and drivers are declared into Maven profiles DDL and DML SQL scripts for each database vendors: docker run --name mysql-petclinic -e MYSQL_ROOT_PASSWORD=petclinic -e MYSQL_DATABASE=petclinic -p 3306:3306 mysql:5.7.8 mvn tomcat7:run-war -P MySQL How to start Spring Petclinic with a MySQL database? data-access.properties
- 8. Bean profiles business-config.xml 3 profiles default (JPA) jdbc Spring Data JPA Inside PetclinicInitializer.javaInside Junit tests No configuration needed in case you wish to use the default profile (jpa) @ContextConfiguration(locations = … }) @RunWith(SpringJUnit4ClassRunner.class) @ActiveProfiles("jpa") public class ClinicServiceJpaTests … { } XmlWebApplicationContext context = new XmlWebApplicationContext(); context.setConfigLocations(…); context.getEnvironment().setDefaultProfiles("jpa"); <beans profile="jpa,spring-data-jpa"> <bean id="entityManagerFactory" … > </beans>
- 9. Caching The list of Veterinarians is cached using ehcache ClinicServiceImpl tools-config.xml ehcache.xml @Cacheable(value = "vets") public Collection<Vet> findVets() throws DataAccessException {…} <cache name="vets" timeToLiveSeconds="60" maxElementsInMemory="100" …/> <!-- Enables scanning for @Cacheable annotation --> <cache:annotation-driven/> <bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheCacheManager" p:cacheManager-ref="ehcache"/> <bean id="ehcache" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" p:configLocation="classpath:cache/ehcache.xml"/>
- 10. Transaction management <!-- Enables scanning for @Transactional annotations --> <tx:annotation-driven/> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" p:entityManagerFactory-ref="entityManagerFactory"/> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager" p:dataSource-ref="dataSource"/> @Transactional(readOnly = true) public Collection<PetType> findPetTypes() throws DataAccessException { return petRepository.findPetTypes(); } business-config.xml ClinicServiceImpl.java Alternative to JPA, Transaction Managers for a single: JPA EntityManagerFactory JDBC DataSource
- 11. Exception Handling PetRepository ClinicService PetController May throw a RuntimeException (typically DataAccessException) Transaction is rolled back in case of a RuntimeException (exception is still propagated to PetController) Exception is not handled there It is propagated. SimpleMapping ExceptionResolver Declared in mvc-core-config.xml Based on the configuration used in petclinic: • Logs the exception stacktrace • Forwards to WEB-INF/jsp/exception.jsp • Exception logged as a comment inside exception.jsp
- 12. Aspect Oriented Programming (1/2) How to add behavior in all methods of all Repository classes? JpaOwnerRepository JpaPetRepository JpaVetRepository JpaVisitRepository ClinicService LOG ALL METHOD CALLS
- 13. Aspect Oriented Programming (2/2) CallMonitoringAspect … @Repository public class JpaVetRepositoryImpl @Repository public class JpaVisitRepositoryImpl Adds monitoring Adds monitoring Adds monitoring @Aspect public class CallMonitoringAspect { @Around("within(@org.springframework.stereotype.Repository *)") public Object invoke(ProceedingJoinPoint joinPoint) throws Throwable { … } To understand further how AOP works in Spring: https://spring.io/blog/2012/05/23/transactions-caching-and-aop-understanding-proxy-usage-in-spring
- 14. View Resolvers in Spring Petclinic ContentNegotiatingViewResolver Does not resolve any view on its own Delegates to other view resolvers BeanName ViewResolver JSON and XML InternalResource ViewResolver Default viewClass: JstlView (used for JSP files) vets.html owners.html vets.xml vets.json mvc-view-config.xml
- 15. Datatables in Spring MVC 15 JSP file <table id="vets" class="table table-striped"> <thead> <tr> <th>Name</th><th>Address</th><th>City</th><th>Telephone</th><th>Pets</th> </tr> </thead> <tbody> <c:forEach items="${selections}" var="owner"> <tr> <td> <spring:url value="/owners/{ownerId}.html" var="ownerUrl"> <spring:param name="ownerId" value="${owner.id}"/> </spring:url> <a href="${fn:escapeXml(ownerUrl)}"><c:out value="${owner.firstName} ${owner.lastName}"/></a> </td> <td> <c:out value="${owner.address}"/> </td> … </tr> </c:forEach> </tbody> </table> Simple HTML tables with Bootstrap style
- 16. Templating Simple JSP custom tags vetList.jsp Main content layout.tag htmlHeader.tag bodyHeader.tag pivotal.tag menu.tag footer.tag jquery.js, jquery-ui.js, bootstrap.js petclinic.css
- 17. Validation Server-side validation with Bean Validation Few annotations on entities: @Digits, @NotEmpty (Hibernate Validator) Custom Spring MVC Validator when required (i.e. PetValidator) @RequestMapping(value = "/owners/new", method = RequestMethod.POST) public String processCreationForm(@Valid Owner owner, BindingResult result) { if (result.hasErrors()) { … public class Owner extends Person { @Column(name = "address") @NotEmpty private String address; ... <c:if test="${status.error}"> <span class="glyphicon glyphicon-remove form-control-feedback" aria-hidden="true"/> <span class="help-inline">${status.errorMessage}</span> </c:if>
- 18. Allow CSS and JS libraries to be imported as Maven libraries Used in Petclinic for jQuery, jQuery-ui, Bootstrap http://www.webjars.org/ Webjars
- 19. Using Webjars Inside pom.xml <dependency> <groupId>org.webjars</groupId> <artifactId>jquery</artifactId> <version>2.2.4</version> </dependency> <mvc:resources mapping="/webjars/**" location="classpath:/META-INF/resources/webjars/"/> Inside JSP (footer.tag) Spring MVC configuration <spring:url value="/webjars/jquery/2.2.4/jquery.min.js" var="jQuery"/> <script src="${jQuery}"></script> The Js file is inside a jar file! Inside IDE
- 20. LESS LESS as a CSS pre-processor See petclinic.less CSS generated by wro4j Integrated to the Maven build See usage of the wro4j-maven-plugin inside the pom.xml Less import from Bootstrap webjar <groups xmlns="http://www.isdc.ro/wro"> <group name="petclinic"> <css>classpath:META-INF/resources/webjars/ bootstrap/3.3.6/less/bootstrap.less</css> <css>/petclinic.less</css> </group> </groups> wro.xml
- 21. Java based configuration Spring XML configuration could be replaced by Java configuration Checkout the javaconfig branch @Configuration @EnableWebMvc @Import(MvcViewConfig.class) @ComponentScan(basePackages = { "org.springfrk.samples.petclinic.web" }) public class MvcCoreConfig extends WebMvcConfigurerAdapter { @Override public void addViewControllers(ViewControllerRegistry reg) { reg.addViewController("/").setViewName("welcome"); } … } MvcCoreConfig.java <import resource="mvc-view-config.xml"/> <context:component-scan base-package="org.springfrk.samples.petclinic.web"/> <mvc:annotation-driven /> <mvc:view-controller path="/" view-name="welcome"/> … mvc-core-config.xml
- 22. Unit Testing @Test public void testProcessUpdateFormHasErrors() throws Exception { mockMvc.perform(post("/owners/{ownerId}/pets/{petId}/edit", 1, 1) .param("name", "Betty") .param("birthDate", "2015/02/12")) .andExpect(model().attributeHasNoErrors("owner")) .andExpect(model().attributeHasErrors("pet")) .andExpect(status().isOk()) .andExpect(view().name("pets/createOrUpdatePetForm")); } Frameworks: Spring Test, JUnit, HSQLDB, Mockito, AssertJ, Hamcrest, Json Path Tests are shared between persistence technologies Inherits from AbstractClinicServiceTests PetControllerTests.java
- 23. Comparing with the original Spring Petclinic Spring Framework Petclinic « Canonical » Spring Petclinic Spring stack Plain Old Spring Framework Spring Boot Architecture 3 layers Aggregate-oriented domain Persistence JDBC, JPA, Spring Data JPA Spring Data JPA View JSP Thymeleaf Databases support HSQLDB, MySQL, PostgreSQL HSQLDB, MySQL Containers support Tomcat 7 and 8, Jetty 9 Embbeded Tomcat and Jetty Java support Java 7 and 8 Java 8 • « Canonical » implementation : https://github.com/spring-projects/spring-petclinic • Spring Framework version : https://github.com/spring-petclinic/spring-framework-petclinic
- 24. Other Spring Petclinic versions Name Technologies Github Spring Petclinic Angular AngularJS 1.x, Spring Boot and Spring Data JPA https://github.com/spring- petclinic/spring-petclinic-angular1 Spring Petclinic React ReactJS (with TypeScript) and Spring Boot https://github.com/spring- petclinic/spring-petclinic-reactjs Spring Petclinic Microservices Distributed version of Spring Petclinic built with Spring Cloud https://github.com/spring- petclinic/spring-petclinic-microservices
- 25. References Transactions, Caching and AOP: understanding proxy usage in Spring (Michael Isvy) Series of 5 blog entries from on how to Improve performance of the Spring-Petclinic application (Julien Dubois) Exception Handling in Spring MVC (Paul Chapman) Spring MVC Test Framework (Rossen Stoyanchev) Empower your CSS in your Maven build (Nicolas Frankel)