Spring Boot 中 Spring Data JPA
JPA是一个基于对象关系映射的标准规范。本文将介绍Spring Boot 与数据库相关简单操作的案例：
1、实战：
1、application.properties
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test
spring.datasource.username=root
spring.datasource.password=wu25471396
#hibernate 提供了根据实体类自动维护数据库表结构的功能
spring.jpa.hibernate.ddl-auto=update
# 在控制台显示sql语句
spring.jpa.show-sql=true
# 让输出的Json字符串更美观
spring.jackson.serialization.indent-output=true2、定义映射实体类
Hibernate支持自动将实体类映射为数据表格
@Entity //表明这是一个与数据库表映射的实体
@NamedQuery(name = "Person.withNameAndAddressNamedQuery",
query = "select p from Person p where p.name=?1 and address=?2 ")
public class Person {
@Id //主键
@GeneratedValue //主键自增，Hibernate 会为我们自动生成一个名为HIBERNATE_SEQUEMCE的序列
private Long id;
private String name;
private Integer age;
private String address;
public Person() {
super();
}
public Person(Long id, String name, Integer age, String address) {
super();
this.id = id;
this.name = name;
this.age = age;
this.address = address;
}
// setter 和 getter 自己写
}
3、定义数据访问接口
public interface PersonRepository extends JpaRepository<Person, Long>{
//使用方法名查询
List<Person> findByAddress(String name);
Person findByNameAndAddress(String name, String address);
//使用@Query查询，参数按照名称绑定
@Query("select p from Person p where p.name = :name and p.address = :address")
Person withNameAndAddressQuery(@Param("name")String name,
@Param("address")String address);
//使用@namedQuery查询，即在实体类中做的@NamedQuery的定义
Person withNameAndAddressNamedQuery(String name, String address);
}5、本该定义业务逻辑层，但由于该入门程序没有复杂业务，本案例就省略了，书写web层
直接将PersonRepository注入到控制器中（以简化演示）。
@RestController
public class DataController {
@Autowired
PersonRepository personRepository;
/**
* 保存
*/
@RequestMapping("/save")
public Person save(String name, String address, Integer age) {
Person p = personRepository.save(new Person(null, name, age, address));
return p;
}
/**
* 测试findByAddress
*/
@RequestMapping("/q1")
public List<Person> q1(String address) {
List<Person> people = personRepository.findByAddress(address);
return people;
}
/**
* 测试findByNameAndAddress
*/
@RequestMapping("/q2")
public Person q2(String name, String address) {
Person people = personRepository.findByNameAndAddress(name, address);
return people;
}
/**
* 测试withNameAndAddressQuery
*/
@RequestMapping("/q3")
public Person q3(String name, String address) {
Person p = personRepository.withNameAndAddressQuery(name, address);
return p;
}
/**
* 测试withNameAndAddressNamedQuery
*/
@RequestMapping("/q4")
public Person q4(String name, String address) {
Person p = personRepository.withNameAndAddressNamedQuery(name, address);
return p;
}
/**
* 测试排序
*/
@RequestMapping("/sort")
public List<Person> sort(){
List<Person> people = personRepository.findAll(new Sort(Sort.Direction.ASC,"age"));
return people;
}
/**
* 测试分页
*/
@RequestMapping("/page")
public Page<Person> page() {
Page<Person> pagePeople = personRepository.findAll(new PageRequest(1, 2));
return pagePeople;
}
}
2、Spring事务操作实战
1、业务层
@Service
public class DemoServiceImpl implements DemoService{
@Autowired
PersonRepository personRepository;
@Transactional(rollbackFor={IllegalArgumentException.class})
public Person savePersonWithRollBack(Person person) {
Person p = personRepository.save(person);
if(person.getName().equals("汪云飞")){
throw new IllegalArgumentException("汪云飞以及存在，数据回滚");
}
return p;
}
@Transactional(noRollbackFor={IllegalArgumentException.class})
public Person savePersonWithoutRollBack(Person person) {
Person p = personRepository.save(person);
if(person.getName().equals("汪云飞")) {
throw new IllegalArgumentException("汪云飞以及存在，数据将不会回滚");
}
return p;
}
}
2、控制器
@RestController
public class MyController {
@Autowired
DemoService demoService;
@RequestMapping("/rollback")
public Person rollback(Person person){
return demoService.savePersonWithRollBack(person);
}
@RequestMapping("/norollback")
public Person noRollback(Person person){
return demoService.savePersonWithoutRollBack(person);
}
}3、Spring 缓存
CacheManager是Spring提供的各种缓存技术抽象接口。
Spring Boot缓存技术实战
业务逻辑：
@Service
public class DemoCacheServiceImpl implements DemoCacheService {
@Autowired
PersonRepository personRepository;
@Override
//@CachePut缓存新增的或更新的数据到缓存，其中缓存名为people，数据的key是person的id
@CachePut(value = "people",key = "#person.id")
public Person save(Person person) {
Person p = personRepository.save(person);
System.out.println("为Id、key为:"+p.getId()+"做了缓存");
return p;
}
@Override
//@CacheEvict从缓存people中删除key为id的数据
@CacheEvict(value = "people")
public void remove(Long id) {
System.out.println("删除了id、key为"+id+"的数据缓冲");
personRepository.deleteById(id);
}
@Override
//@Cacheable 缓存key为person的id的数据到缓存pepple中
@Cacheable(value = "people",key = "#person.id")
public Person findOne(Person person) {
Person p = personRepository.findById(person.getId()).orElse(null);
System.out.println("为id、key为:"+p.getId()+"数据做了缓存");
return p;
}
}
控制层：
@RestController
public class CacheController {
@Autowired
DemoCacheService demoCacheService;
@RequestMapping("/put")
public Person put(Person person){
return demoCacheService.save(person);
}
@RequestMapping("/able")
public Person cacheable(Person person){
return demoCacheService.findOne(person);
}
@RequestMapping("/evit")
public String evit(Long id){
demoCacheService.remove(id);
return "OK";
}
}开启缓存支持：
@SpringBootApplication
@EnableCaching //开启缓存支持
public class Ch82Application {
public static void main(String[] args) {
SpringApplication.run(Ch82Application.class, args);
}
}