spring4.0之八：Groovy DSL

4.0的一个重要特征就是完全支持Groovy，Groovy是Spring主导的一门基于JVM的脚本语言（动态语言）。在spring 2.x，脚本语言通过 Java scripting engine在Spring中得到支持。而在4.0中，Groovy的变得更重要，Groovy可以替换xml和注解用来作为bean配置。

要使用Groovy，首先用maven下载Groovy的包，pom.xml文件中添加：

<dependency>
 <groupId>org.codehaus.groovy</groupId>
 <artifactId>groovy-all</artifactId>
 <version>2.1.8</version>
</dependency>

 下面使用xml，java annotation，groovy dsl实现相同功能的不同配置方式比较

XML

<jdbc:embedded-database id="dataSource" type="H2">
</jdbc:embedded-database>

<bean
 class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"
 id="entityManagerFactory">
 <property name="persistenceUnitName" value="persistenceUnit" />
 <property name="dataSource" ref="dataSource" />
 <property name="persistenceProviderClass" value="org.hibernate.ejb.HibernatePersistence"></property>
 <property name="packagesToScan">
  <array>
   <value>com.hantsylabs.example.spring.model</value>
  </array>
 </property>
 <property name="jpaProperties">
  <value>
   hibernate.format_sql=true
   hibernate.show_sql=true
   hibernate.hbm2ddl.auto=create
  </value>
 </property>
</bean>

<bean class="org.springframework.orm.jpa.JpaTransactionManager"
 id="transactionManager">
 <property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>

Annotation

@Configuration
@ComponentScan(basePackages = { "com.hantsylabs.example.spring.dao","com.hantsylabs.example.spring.jpa" })
@EnableTransactionManagement(mode=AdviceMode.ASPECTJ)
public class JpaConfig {

 @Bean
 public DataSource dataSource() {
  return new EmbeddedDatabaseBuilder().setType(EmbeddedDatabaseType.H2).build();
 }

 @Bean
 public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
  LocalContainerEntityManagerFactoryBean emf = new LocalContainerEntityManagerFactoryBean();
  emf.setDataSource(dataSource());
  emf.setPackagesToScan("com.hantsylabs.example.spring.model");
  emf.setPersistenceProvider(new HibernatePersistence());
  emf.setJpaProperties(jpaProperties());
  return emf;
 }

 private Properties jpaProperties() {
  Properties extraProperties = new Properties();
  extraProperties.put("hibernate.format_sql", "true");
  extraProperties.put("hibernate.show_sql", "true");
  extraProperties.put("hibernate.hbm2ddl.auto", "create");
  return extraProperties;
 }

 @Bean
 public PlatformTransactionManager transactionManager() {
  return new JpaTransactionManager(entityManagerFactory().getObject());
 }

}

Groovy DSL

import org.apache.commons.dbcp.BasicDataSource
import org.springframework.orm.jpa.JpaTransactionManager
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean
import com.hantsylabs.example.spring.jpa.JpaConferenceDaoImpl

beans {
     dataSource(BasicDataSource) {
         driverClassName = "org.h2.Driver"
         url = "jdbc:h2:mem:spring4-sandbox"
         username = "sa"
         password = ""
     }

  entityManagerFactory(LocalContainerEntityManagerFactoryBean){
   persistenceProviderClass="org.hibernate.ejb.HibernatePersistence"
   dataSource=dataSource
   persistenceUnitName="persistenceUnit"
   packagesToScan=["com.hantsylabs.example.spring.model"]
   jpaProperties=[
    "hibernate.format_sql":"true",
    "hibernate.show_sql":"true",
    "hibernate.hbm2ddl.auto":"create"
    ]
  }

  transactionManager(JpaTransactionManager){
   entityManagerFactory=entityManagerFactory
  }

  conferenceDao(JpaConferenceDaoImpl){
  }

 }