Migrate Spring application from XML in annotations

Question

I have inherited a Spring 3 application that uses XML files to define and join beans together. I know that with Spring 2 they can be replaced mostly with annotations. I would like Spring:

• discovers beans by scanning specific packages for classes with any annotation used to refer to Spring bean
• attempt of autwire-by-name and field in a bean, which I noted with the corresponding annotation

What steps should I take to make this happen?

Answer 1

The manual contains all the necessary information: http://static.springsource.org/spring/docs/3.1.0.M1/spring-framework-reference/html/beans.html#beans-annotation-config

TL version; DR is that you need to add <context:annotation-config/> to your spring configuration and then annotate your beans with @Component and annotate with @Autowired in your property set

Answer 2

I think the first thing to do is to go slowly. Just select one service at a time and transfer it, because you have a reason to touch it. Dumping with a ton of spring config is a surefire way to insert yourself into production with dependencies that you will only need from time to time.

Answer 3

I will give you the xml configuration with the corresponding analog equivalent, so you can easily see how to change the bean from xml to java and vice versa

  `<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd"> <context:component-scan base-package="com.mycompany.backendhibernatejpa.controller" /> <mvc:annotation-driven /> <bean id="iAbonneDao" class="com.mycompany.backendhibernatejpa.daoImpl.AbonneDaoImpl"/> <bean id="iAbonneService" class="com.mycompany.backendhibernatejpa.serviceImpl.AbonneServiceImpl"/> <!-- couche de persistance JPA --> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="dataSource" ref="dataSource" /> <property name="jpaVendorAdapter"> <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"> <property name="databasePlatform" value="org.hibernate.dialect.MySQL5InnoDBDialect" /> <property name="generateDdl" value="true" /> <property name="showSql" value="true" /> </bean> </property> <property name="loadTimeWeaver"> <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver" /> </property> </bean> <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations" value="classpath:bd.properties"/> </bean> <!-- la source de donnéees DBCP --> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close" > <property name="driverClassName" value="${bd.driver}" /> <property name="url" value="${bd.url}" /> <property name="username" value="${bd.username}" /> <property name="password" value="${bd.password}" /> </bean> <!-- le gestionnaire de transactions --> <bean id="txManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory" /> </bean> <!-- traduction des exceptions --> <bean class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" /> <!-- annotations de persistance --> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor" /> </beans>` 

this file is called springrest-sevlet. in fact, you can name the name you want followed by "-server" and specify that name in the web.xml file

  ` <web-app> <display-name>Gescable</display-name> <servlet> <servlet-name>springrest</servlet-name> <servlet-class> org.springframework.web.servlet.DispatcherServlet </servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>springrest</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> </web-app>` 

two files should be placed in the "WEB-INF" folder. Now equivalent with anotation based configuration

  `/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */ package com.mycompany.backendhibernatejpaannotation.configuration; import com.mycompany.backendhibernatejpaannotation.daoImpl.AbonneDaoImpl; import com.mycompany.backendhibernatejpaannotation.daoInterface.IAbonneDao; import com.mycompany.backendhibernatejpaannotation.serviceImpl.AbonneServiceImpl; import com.mycompany.backendhibernatejpaannotation.serviceInterface.IAbonneService; import javax.sql.DataSource; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor; import org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver; import org.springframework.jdbc.datasource.DriverManagerDataSource; import org.springframework.orm.jpa.JpaTransactionManager; import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean; import org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor; import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter; import org.springframework.web.servlet.config.annotation.EnableWebMvc; /** * * @author vivien saa */ @Configuration @EnableWebMvc @ComponentScan(basePackages = "com.mycompany.backendhibernatejpaannotation") public class RestConfiguration { @Bean public IAbonneDao iAbonneDao() { return new AbonneDaoImpl(); } @Bean public IAbonneService iAbonneService() { return new AbonneServiceImpl(); } // @Bean // public PropertyPlaceholderConfigurer placeholderConfigurer() { // PropertyPlaceholderConfigurer placeholderConfigurer = new PropertyPlaceholderConfigurer(); // placeholderConfigurer.setLocations("classpath:bd.properties"); // return placeholderConfigurer; // } @Bean public DataSource dataSource() { DriverManagerDataSource dataSource = new DriverManagerDataSource(); dataSource.setDriverClassName("com.mysql.jdbc.Driver"); dataSource.setUrl("jdbc:mysql://localhost:3306/gescable"); dataSource.setUsername("root"); dataSource.setPassword("root"); return dataSource; } @Bean public HibernateJpaVendorAdapter jpaVendorAdapter() { HibernateJpaVendorAdapter jpaVendorAdapter = new HibernateJpaVendorAdapter(); jpaVendorAdapter.setDatabasePlatform("org.hibernate.dialect.MySQL5InnoDBDialect"); jpaVendorAdapter.setGenerateDdl(true); jpaVendorAdapter.setShowSql(true); return jpaVendorAdapter; } @Bean public InstrumentationLoadTimeWeaver loadTimeWeaver() { InstrumentationLoadTimeWeaver loadTimeWeaver = new InstrumentationLoadTimeWeaver(); return loadTimeWeaver; } @Bean public LocalContainerEntityManagerFactoryBean entityManagerFactory() { LocalContainerEntityManagerFactoryBean entityManagerFactory = new LocalContainerEntityManagerFactoryBean(); entityManagerFactory.setDataSource(dataSource()); entityManagerFactory.setJpaVendorAdapter(jpaVendorAdapter()); entityManagerFactory.setLoadTimeWeaver(loadTimeWeaver()); return entityManagerFactory; } @Bean public JpaTransactionManager jpaTransactionManager() { JpaTransactionManager jpaTransactionManager = new JpaTransactionManager(); jpaTransactionManager.setEntityManagerFactory(entityManagerFactory().getObject()); return jpaTransactionManager; } @Bean public PersistenceExceptionTranslationPostPro`enter code here`cessor persistenceExceptionTranslationPostProcessor() { return new PersistenceExceptionTranslationPostProcessor(); } @Bean public PersistenceAnnotationBeanPostProcessor persistenceAnnotationBeanPostProcessor() { return new PersistenceAnnotationBeanPostProcessor(); } }` 

This file must be accompanied by this

 ` package com.mycompany.backendhibernatejpaannotation.configuration; import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer; /** * * @author vivien saa */ public class Initializer extends AbstractAnnotationConfigDispatcherServletInitializer { @Override protected Class<?>[] getRootConfigClasses() { return new Class[]{RestConfiguration.class}; } @Override protected Class<?>[] getServletConfigClasses() { return null; } @Override protected String[] getServletMappings() { return new String[]{"/"}; } } `