实践Spring Data JPA

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Spring Data JPA, part of the larger Spring Data family, makes it easy to easily implement JPA based repositories. This module deals with enhanced support for JPA based data access layers. It makes it easier to build Spring-powered applications that use data access technologies.

相比较于原始JPA或Spring JPA，Spring Data JPA封装和扩展更进了一步。基于XML和JavaConfig方式参考如下：

JPA xml namespace

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/data/jpa
http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">
	<!-- repository所在包 -->
  	<jpa:repositories base-package="com.acme.repositories"/>
</beans>

JPA JavaConfig

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@Configuration
@EnableJpaRepositories(basePackages="spittr.db")
@EnableTransactionManagement
class ApplicationConfig {
    @Bean
    public DataSource dataSource() {
        EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder();
        return builder.setType(EmbeddedDatabaseType.HSQL).build();
    }
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setGenerateDdl(true);
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setJpaVendorAdapter(vendorAdapter);
        factory.setPackagesToScan("com.acme.domain");
        factory.setDataSource(dataSource());
        return factory;
    }
    @Bean
    public PlatformTransactionManager transactionManager() {
        JpaTransactionManager txManager = new JpaTransactionManager();
        txManager.setEntityManagerFactory(entityManagerFactory());
        return txManager;
    }
}

Jpa Repositories

spring-data-JpaRepository

定义泛型参数化的继承Spring Data JPA的某一个接口，自动生成实现（org.springframework.data.jpa.repository.support.SimpleJpaRepository<T, ID>），拥有18个基本方法

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<SpringDataJpaRepository接口> extends JpaRepository<Model, Long>