Spring Boot实战-使用WebFlux进行响应式编程（2）

@RestController
@RequestMapping("/user")
public class UserController {

    private final UserService userService;

    @Autowired
    public UserController(final UserService userService) {
        this.userService = userService;
    }

    @ResponseStatus(value = HttpStatus.NOT_FOUND, reason = "Resource not found")
    @ExceptionHandler(ResourceNotFoundException.class)
    public void notFound() {
    }

    @GetMapping("")
    public Flux<User> list() {
        return this.userService.list();
    }

    @GetMapping("/{id}")
    public Mono<User> getById(@PathVariable("id") final String id) {
        return this.userService.getById(id);
    }

    @PostMapping("")
    public Mono<User> create(@RequestBody final User user) {
        return this.userService.createOrUpdate(user);
    }

    @PutMapping("/{id}")
    public Mono<User>  update(@PathVariable("id") final String id, @RequestBody final User user) {
        Objects.requireNonNull(user);
        user.setId(id);
        return this.userService.createOrUpdate(user);
    }

    @DeleteMapping("/{id}")
    public Mono<User>  delete(@PathVariable("id") final String id) {
        return this.userService.delete(id);
    }
}

@Service
public class UserService {
    private final Map<String, User> data = new ConcurrentHashMap<>();

    public Flux<User> list() {
        return Flux.fromIterable(this.data.values());
    }

    public Flux<User> getById(final Flux<String> ids) {
        return ids.flatMap(id -> Mono.justOrEmpty(this.data.get(id)));
    }

    public Mono<User> getById(final String id) {
        return Mono.justOrEmpty(this.data.get(id))
                .switchIfEmpty(Mono.error(new ResourceNotFoundException()));
    }

    public Mono<User> createOrUpdate(final User user) {
        this.data.put(user.getId(), user);
        return Mono.just(user);
    }

    public Mono<User> delete(final String id) {
        return Mono.justOrEmpty(this.data.remove(id));
    }
     public void fromStream () {
        SortedMap<String, Charset> charSetMap = Charset.availableCharsets();
        Stream<String> charSetStream = charSetMap.keySet().stream();
        Flux<String> charsetFlux = Flux.fromStream(charSetStream);
        charsetFlux.subscribe(System.out::println);
    }

      public void range() {
        Flux.range(1, 5).subscribe(System.out::println);
        // 溢出
        Flux.range(Integer.MAX_VALUE, 5).subscribe(System.out::println);
    }
}