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前情提要
上回书说到,用Spring Boot写了一个Hello World小例子,那么今天就来完成上篇结尾留下的增删改查的实例。
软件环境
- Windows 10
- JDK 11
- IDEA 2018.2
- Maven 3.5.4
- MySQL 8.0.12
代码
pom文件中需要添加一下依赖:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.12</version>
</dependency>
<dependency>
<groupId>org.javassist</groupId>
<artifactId>javassist</artifactId>
<version>3.23.1-GA</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
yml文件:
server:
port: 8080
servlet:
path: /hello
spring:
datasource:
driver-class-name: com.mysql.cj.jdbc.Driver
url: jdbc:mysql://localhost:3306/helloboot?serverTimezone=Asia/Shanghai&allowPublicKeyRetrieval=true&useSSL=false
username: root
password: root
jpa:
show-sql: true
Controller:
@RestController()
public class UserController {
@Autowired
private UserRepository userRepository;
@PostMapping("/user")
public User save(User user) {
return userRepository.save(user);
}
@PutMapping("/user")
public User update(User user) {
return userRepository.save(user);
}
@GetMapping("/user/{id}")
public User findById(@PathVariable("id") Integer id) {
return userRepository.findById(id).get();
}
@DeleteMapping("/user/{id}")
public void delete(@PathVariable("id") Integer id) {
userRepository.deleteById(id);
}
}
由于过于简单,就省去Service层了。
Dao层:
public interface UserRepository extends JpaRepository<User, Integer> {
}
Dao层简单到令人发指!完成一个基本的CRUD只需要定义一个接口,不需要写任何实现和SQL。
实体
@Entity
@Data
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
private Integer age;
}
如果想要实现更多功能,依然简单到爆炸,只需要按照下表的规则,就能实现各种查询操作,不需要写任何实现和SQL。
内置关键字:
Keyword | Sample | JPQL snippet |
---|---|---|
And | findByLastnameAndFirstname | … where x.lastname = ?1 and x.firstname = ?2 |
Or | findByLastnameOrFirstname | … where x.lastname = ?1 or x.firstname = ?2 |
Is,Equals | findByFirstname,findByFirstnameIs,findByFirstnameEquals | … where x.firstname = ?1 |
Between | findByStartDateBetween | … where x.startDate between ?1 and ?2 |
LessThan | findByAgeLessThan | … where x.age < ?1 |
LessThanEqual | findByAgeLessThanEqual | … where x.age <= ?1 |
GreaterThan | findByAgeGreaterThan | … where x.age > ?1 |
GreaterThanEqual | findByAgeGreaterThanEqual | … where x.age >= ?1 |
After | findByStartDateAfter | … where x.startDate > ?1 |
Before | findByStartDateBefore | … where x.startDate < ?1 |
IsNull | findByAgeIsNull | … where x.age is null |
IsNotNull,NotNull | findByAge(Is)NotNull | … where x.age not null |
Like | findByFirstnameLike | … where x.firstname like ?1 |
NotLike | findByFirstnameNotLike | … where x.firstname not like ?1 |
StartingWith | findByFirstnameStartingWith | … where x.firstname like ?1 (parameter bound with appended %) |
EndingWith | findByFirstnameEndingWith | … where x.firstname like ?1 (parameter bound with prepended %) |
Containing | findByFirstnameContaining | … where x.firstname like ?1 (parameter bound wrapped in %) |
OrderBy | findByAgeOrderByLastnameDesc | … where x.age = ?1 order by x.lastname desc |
Not | findByLastnameNot | … where x.lastname <> ?1 |
In | findByAgeIn(Collection ages) | … where x.age in ?1 |
NotIn | findByAgeNotIn(Collection ages) | … where x.age not in ?1 |
True | findByActiveTrue() | … where x.active = true |
False | findByActiveFalse() | … where x.active = false |
IgnoreCase | findByFirstnameIgnoreCase | … where UPPER(x.firstame) = UPPER(?1) |