spring data 之 Spring Data JPA
Spring Data 是一些令人兴奋的技术公司和开发人员开发的，让用新的数据库访问技术使用更方便。包含了多个子项目。
http://spring.io/guides/gs/accessing-data-jpa/
定义简单的实体类Customer：
//@Entity表明该实体未JPA实体，对应数据库中的Customer表，@Table
@Entity
public class Customer {
//
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private long id;
private String firstName;
private String lastName;
protected Customer() {}
public Customer(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
@Override
public String toString() {
return String.format(
"Customer[id=%d, firstName='%s', lastName='%s']",
id, firstName, lastName);
}
}
Spring Data JPA 关注在关系型数据库使用JPA存储数据。最引人注目的功能是在运行时从一个respoitory接口 自动创建repository实现类。
public interface CustomerRepository extends CrudRepository<Customer, Long> {
List<Customer> findByLastName(String lastName);
}
http://spring.io/guides/gs/accessing-data-jpa/
定义简单的实体类Customer：
//@Entity表明该实体未JPA实体，对应数据库中的Customer表，@Table
@Entity
public class Customer {
//
@Id so that JPA will recognize it as the object’s ID. The id property is also annotated with @GeneratedValue to indicate that the ID should be generated automatically.
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
private long id;
private String firstName;
private String lastName;
protected Customer() {}
public Customer(String firstName, String lastName) {
this.firstName = firstName;
this.lastName = lastName;
}
@Override
public String toString() {
return String.format(
"Customer[id=%d, firstName='%s', lastName='%s']",
id, firstName, lastName);
}
}
Spring Data JPA 关注在关系型数据库使用JPA存储数据。最引人注目的功能是在运行时从一个respoitory接口 自动创建repository实现类。
public interface CustomerRepository extends CrudRepository<Customer, Long> {
List<Customer> findByLastName(String lastName);
}
CustomerRepository 继承了CrudRepository 接口，通过泛型，指定了实体类型和ID类型为Customer和Long。CrudRepository 包括多个持久化方法，包括保存、删除和查找Customer实体。Spring Data JPA同样允许自定义其它的查询方法。
EnableJpaRepositories 注解，表明Spring Data JPA遍历任何实现了org.springframework.data.repository.Repository
@Configuration
@EnableJpaRepositories
public class Application {
@Bean
public DataSource dataSource() {
return new EmbeddedDatabaseBuilder().setType(H2).build();
}
@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter) {
LocalContainerEntityManagerFactoryBean lef = new LocalContainerEntityManagerFactoryBean();
lef.setDataSource(dataSource);
lef.setJpaVendorAdapter(jpaVendorAdapter);
lef.setPackagesToScan("hello");
return lef;
}
@Bean
public JpaVendorAdapter jpaVendorAdapter() {
HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
hibernateJpaVendorAdapter.setShowSql(false);
hibernateJpaVendorAdapter.setGenerateDdl(true);
hibernateJpaVendorAdapter.setDatabase(Database.H2);
return hibernateJpaVendorAdapter;
}
@Bean
public PlatformTransactionManager transactionManager() {
return new JpaTransactionManager();
}
public static void main(String[] args) {
AbstractApplicationContext context = new AnnotationConfigApplicationContext(Application.class);
CustomerRepository repository = context.getBean(CustomerRepository.class);
// save a couple of customers
repository.save(new Customer("Jack", "Bauer"));
repository.save(new Customer("Chloe", "O'Brian"));
repository.save(new Customer("Kim", "Bauer"));
repository.save(new Customer("David", "Palmer"));
repository.save(new Customer("Michelle", "Dessler"));
// fetch all customers
Iterable<Customer> customers = repository.findAll();
System.out.println("Customers found with findAll():");
System.out.println("-------------------------------");
for (Customer customer : customers) {
System.out.println(customer);
}
System.out.println();
// fetch an individual customer by ID
Customer customer = repository.findOne(1L);
System.out.println("Customer found with findOne(1L):");
System.out.println("--------------------------------");
System.out.println(customer);
System.out.println();
// fetch customers by last name
List<Customer> bauers = repository.findByLastName("Bauer");
System.out.println("Customer found with findByLastName('Bauer'):");
System.out.println("--------------------------------------------");
for (Customer bauer : bauers) {
System.out.println(bauer);
}
context.close();
}
}
maven pom文件
<?xml version="1.0" encoding="UTF-8"?>
<project
xmlns=
"http://maven.apache.org/POM/4.0.0"
xsi:schemaLocation=
"http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"
xmlns:xsi=
"http://www.w3.org/2001/XMLSchema-instance"
>
<modelVersion>4.0.0
</modelVersion>
<groupId>org.springframework
</groupId>
<artifactId>gs-accessing-data-jpa
</artifactId>
<version>0.1.0
</version>
<parent>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-starter-parent
</artifactId>
<version>0.5.0.M6
</version>
</parent>
<dependencies>
<dependency>
<groupId>org.springframework
</groupId>
<artifactId>spring-orm
</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.data
</groupId>
<artifactId>spring-data-jpa
</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot
</groupId>
<artifactId>spring-boot-starter-web
</artifactId>
</dependency>
<dependency>
<groupId>org.hibernate
</groupId>
<artifactId>hibernate-entitymanager
</artifactId>
</dependency>
<dependency>
<groupId>com.h2database
</groupId>
<artifactId>h2
</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin
</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones
</id>
<name>Spring Milestones
</name>
<url>http://repo.spring.io/libs-milestone
</url>
<snapshots>
<enabled>false
</enabled>
</snapshots>
</repository>
<repository>
<id>org.jboss.repository.releases
</id>
<name>JBoss Maven Release Repository
</name>
<url>https://repository.jboss.org/nexus/content/repositories/releases
</url>
<snapshots>
<enabled>false
</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestones
</id>
<name>Spring Milestones
</name>
<url>http://repo.spring.io/libs-milestone
</url>
<snapshots>
<enabled>false
</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories>
</project>