Spring webflux 函數式編程web框架

Spring webflux

Spring 5.0 Spring webflux 是一個全新的非堵塞的函數式 Reactive Web 框架，能夠用來構建異步的、非堵塞的、事件驅動的服務。 springboot2.0發佈不久，最近研究了一下springboot2.0的新特性,其中就發現了webflux。

下面是spring-flux的一個demo話很少少上代碼

使用webflux和MVC的區別就是在artifacId後面加上flux

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>2.0.0.RELEASE</version>
</parent>
<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
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@RestController
public class HelloController {
	@GetMapping("/hello")
	public String hello() {
		return "hello world";
	}
}
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在webflux中有Handler和Router 的概念，分別與springmvc中的controllerr和equest mapper相對應,通俗的將就是handler就是真正處理請求的bean，能夠在handler中編寫處理請求的邏輯，而Router就是如何讓請求找到對應的handler中的方法處理，下面咱們來實現一個簡單的handler和router。

@Component
public class HelloWorldHandler {

    public Mono<ServerResponse> helloWorld(ServerRequest request){
        return ServerResponse.ok()
                .contentType(MediaType.TEXT_PLAIN)
                .body(BodyInserters.fromObject("hello flux"));
    }
    
}
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上面是一個簡單的handler只相應了一個「hello flux」 字符串！

@Configuration
public class RouterConfig {

    @Autowired
    private HelloWorldHandler helloWorldHandler;

    @Bean
    public RouterFunction<?> helloRouter() {
        return RouterFunctions.route(RequestPredicates.GET("/hello"), helloWorldHandler::helloWorld);
    }

}
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上面是對應的router對應的是匹配一個get方式的/hello請求，而後調用helloWorldHandler中的helloWorld方法向瀏覽器輸出一個文本類型的字符串

再來一個例子

@Component
public class UserHandler {

    @Autowired
    private ReactiveRedisConnection connection;

    public Mono<ServerResponse> getTime(ServerRequest request) {
        return ServerResponse.ok().contentType(MediaType.TEXT_PLAIN)
                .body(Mono.just("Now is " + new SimpleDateFormat("HH:mm:ss").format(new Date())), String.class);
    }
    public Mono<ServerResponse> getDate(ServerRequest request) {
        return ServerResponse.ok().contentType(MediaType.TEXT_PLAIN)
                .body(Mono.just("Today is " + new SimpleDateFormat("yyyy-MM-dd").format(new Date())), String.class);
    }

    public Mono<ServerResponse> sendTimePerSec(ServerRequest request) {
        return ServerResponse.ok().contentType(MediaType.TEXT_EVENT_STREAM)
                .body(Flux.interval(Duration.ofSeconds(1)).map(l -> new SimpleDateFormat("HH:mm:ss").format(new Date())), String.class);
    }


    public Mono<ServerResponse> register(ServerRequest request) {
        Mono<Map> body = request.bodyToMono(Map.class);
        return body.flatMap(map -> {
            String username = (String) map.get("username");
            String password = (String) map.get("password");
            String hashedPassword = BCrypt.hashpw(password, BCrypt.gensalt());
            return connection.stringCommands()
                    .set(ByteBuffer.wrap(username.getBytes()), ByteBuffer.wrap(hashedPassword.getBytes()));
        }).flatMap(aBoolean -> {
            Map<String, String> result = new HashMap<>();
            ServerResponse serverResponse = null;
            if (aBoolean){
                result.put("message", "successful");
                return ServerResponse.ok()
                        .contentType(MediaType.APPLICATION_JSON_UTF8)
                        .body(BodyInserters.fromObject(result));
            }else {
                result.put("message", "failed");
                return ServerResponse.status(HttpStatus.BAD_REQUEST)
                        .contentType(MediaType.APPLICATION_JSON_UTF8)
                        .body(BodyInserters.fromObject(request));
            }
        });

    }

    public Mono<ServerResponse> login(ServerRequest request) {
        Mono<Map> body = request.bodyToMono(Map.class);
        return body.flatMap(map -> {
            String username = (String) map.get("username");
            String password = (String) map.get("password");
            return connection.stringCommands().get(ByteBuffer.wrap(username.getBytes())).flatMap(byteBuffer -> {
                byte[] bytes = new byte[byteBuffer.remaining()];
                byteBuffer.get(bytes, 0, bytes.length);
                String hashedPassword = null;
                try {
                    hashedPassword = new String(bytes, "UTF-8");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
                Map<String, String> result = new HashMap<>();
                if (hashedPassword == null || !BCrypt.checkpw(password, hashedPassword)) {
                    result.put("message", "帳號或密碼錯誤");
                    return ServerResponse.status(HttpStatus.UNAUTHORIZED)
                            .contentType(MediaType.APPLICATION_JSON_UTF8)
                            .body(BodyInserters.fromObject(result));
                } else {
                    result.put("token", "無效token");
                    return ServerResponse.ok()
                            .contentType(MediaType.APPLICATION_JSON_UTF8)
                            .body(BodyInserters.fromObject(result));
                }
            });
        });
    }


}
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@Configuration
public class RouterConfig {

    @Autowired
    private HelloWorldHandler helloWorldHandler;

    @Bean
    public RouterFunction<?> helloRouter() {
        return RouterFunctions.route(RequestPredicates.GET("/hello"), helloWorldHandler::helloWorld);
    }

    @Autowired
    private UserHandler userHandler;

    @Bean
    public RouterFunction<ServerResponse> timerRouter() {
        return RouterFunctions.route(RequestPredicates.GET("/time"), userHandler::getTime)
                .andRoute(RequestPredicates.GET("/date"), userHandler::getDate);
    }

    @Bean
    public RouterFunction<?> routerFunction() {
        return RouterFunctions.route(RequestPredicates.GET("/hello"), helloWorldHandler::helloWorld)
                .andRoute(RequestPredicates.POST("/register"), userHandler::register)
                .andRoute(RequestPredicates.POST("/login"), userHandler::login)
                .andRoute(RequestPredicates.GET("/times"), userHandler::sendTimePerSec);
    }

}
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