FastAPI 入门

@RestController
class UserController {
    @GetMapping("/users/{id}")
    User getUser(@PathVariable int id) {
        return new User(id, "Ada");
    }
}

interface UserApi {
    @GET("users/{id}")
    suspend fun getUser(@Path("id") id: Int): User
}

@GetMapping("/users/{id}/posts")
PostPage listPosts(
    @PathVariable int id,
    @RequestParam(defaultValue = "1") @Min(1) int page,
    @RequestParam(required = false) String keyword
) {
    return service.find(id, page, keyword);
}

@GET("users/{id}/posts")
suspend fun listPosts(
    @Path("id") id: Int,
    @Query("page") page: Int = 1,
    @Query("keyword") keyword: String? = null,
): PostPage

record UserCreate(@Size(min = 1) String name, String password) {}

record UserPublic(int id, String name) {}

@PostMapping("/users")
@ResponseStatus(HttpStatus.CREATED)
UserPublic createUser(@Valid @RequestBody UserCreate user) {
    return new UserPublic(1, user.name());
}

@Serializable
data class UserCreate(
    val name: String,
    val password: String,
)

@Serializable
data class UserPublic(val id: Int, val name: String)

@POST("users")
suspend fun createUser(
    @Body user: UserCreate,
): UserPublic

@GetMapping("/users/{id}")
User getUser(@PathVariable int id) {
    var name = USERS.get(id);
    if (name == null) {
        throw new ResponseStatusException(
            HttpStatus.NOT_FOUND, "用户不存在");
    }
    return new User(id, name);
}

try {
    api.getUser(9)
} catch (e: HttpException) {
    println(e.code())
    println(e.response()?.errorBody()?.string())
}

@Component
class TokenStore {
    String userOf(String token) {
        if (!"secret".equals(token)) {
            throw new ResponseStatusException(HttpStatus.UNAUTHORIZED);
        }
        return "ada";
    }
}

@RestController
class MeController {
    private final TokenStore tokens;

    MeController(TokenStore tokens) {
        this.tokens = tokens;
    }

    @GetMapping("/me")
    Map<String, String> readMe(@RequestHeader("X-Token") String token) {
        return Map.of("user", tokens.userOf(token));
    }
}

@Module
@InstallIn(SingletonComponent::class)
object AuthModule {
    @Provides
    fun tokenStore(): TokenStore = TokenStore()
}

class MeRepository @Inject constructor(
    private val tokens: TokenStore,
)

// WebFlux 运行在事件循环上
@GetMapping("/good")
Mono<String> good() {
    return Mono.delay(Duration.ofMillis(10))  // 不占线程
        .thenReturn("ok");
}

@GetMapping("/bad")
Mono<String> bad() throws InterruptedException {
    Thread.sleep(10);  // 阻塞，所有请求都要等它
    return Mono.just("ok");
}

@GetMapping("/fine")
Mono<String> fine() {
    return Mono.fromCallable(() -> {
        Thread.sleep(10);  // 放到线程池，不影响别的请求
        return "ok";
    }).subscribeOn(Schedulers.boundedElastic());
}

// 运行在 Dispatchers.Main 上
suspend fun good() {
    delay(10)  // 挂起，主线程继续处理别的事
}

suspend fun bad() {
    Thread.sleep(10)  // 阻塞，界面跟着卡住
}

suspend fun fine() = withContext(Dispatchers.IO) {
    Thread.sleep(10)  // 切到后台线程，不影响主线程
}

@WebMvcTest(MeController.class)
class MeControllerTest {
    @Autowired MockMvc mvc;
    @MockitoBean TokenStore tokens;

    @Test
    void readsUser() throws Exception {
        when(tokens.userOf("t")).thenReturn("tester");
        mvc.perform(get("/me").header("X-Token", "t"))
            .andExpect(jsonPath("$.user").value("tester"));
    }
}

@HiltAndroidTest
class MeRepositoryTest {
    @get:Rule
    val hiltRule = HiltAndroidRule(this)

    @BindValue
    val tokens: TokenStore = FakeTokenStore()

    @Inject
    lateinit var repository: MeRepository

    @Test
    fun readsUser() {
        hiltRule.inject()
        assertEquals("tester", repository.currentUser())
    }
}