To implement REST services in Spring 5, follow these steps:
- To enable Spring REST support, add the following starter POM dependency:
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-rest</artifactId> </dependency>
- All the annotations of SpringDataConfig needed to implement Spring Data JPA are also needed here for Spring REST configuration.
- Inside org.packt.spring.boot.dao, create a DepartmentRepository that extends JpaRespository, which is the same API class used in the previous recipe:
@RepositoryRestResource(collectionResourceRel="depts",
path="depts")
public interface DepartmentRepository
extends JpaRepository<Department, Integer>{
public List<Department> findByName(@Param("name") String name);
public List<Department> findByDeptid(
@Param("deptid") Integer deptId);
}
The optional annotation @RepositoryRestResource is present because the requirement wants the REST endpoint name to be shorter as /depts than the default, which is /departments. Moreover, the @Param is required to map the local parameter of the operations to the request parameter value sent by the client.
- To parse all the JSON request and response, inject the beans concerning JSON converters to SpringDataConfig from RepositoryRestMvcConfiguration by using @Import. Thus, there is no need to add the com.fasterxml.jackson.core dependency.
- However, even without Spring REST, Spring 5's reactive application can expose any data using @RestController of Spring MVC components. The usual @RequestMapping can still be used to map the handler to the URL with the indicated HTTP method. But the modern way of mapping requests to a URL is through the use of @GetMapping and @PostMapping annotations:
@RestController
public class RestServiceController {
@Autowired
private EmployeeService employeeServiceImpl;
@RequestMapping("/objectSampleRest")
public String exposeString() {
return "Hello World";
}
@GetMapping("/monoSampleRest")
public Mono<String> exposeMono() {
return Mono.just("Hello World");
}
@GetMapping("/fluxSampleRest")
public Flux<String> exposeFlux() {
List<String> names = Arrays.asList("Anna", "John", "Lucy");
return Flux.fromIterable(names)
.map((str) -> str.toUpperCase() + "---");
}
@GetMapping("/fluxJpaEmps")
public Flux<Employee> exposeJpaEmps() {
return Flux.fromIterable(
employeeServiceImpl.findAllEmps());
}
@PostMapping(path = "/fluxAddEmp",
consumes = MediaType.APPLICATION_JSON_VALUE)
public void addMonoEmp(@RequestBody Mono<Employee> employee){
}
@PostMapping(path = "/fluxAddListEmps",
consumes = MediaType.APPLICATION_JSON_VALUE)
public void addFluxEmp(@RequestBody Flux<Employee> employee){
}
}
- Save all files. Then clean and deploy the standalone Spring Boot application. Open a browser and run http://localhost:8093/ch09-flux/fluxJpaEmps.
