Reactive programming WebFlux

A, WebFlux Profile

SpringBoot2.xUnderlying used Spring5, Spring5it introduced the reactive programming Spring WebFlux.

WebFluxFeatures:

① SpringMVCis the IO model synchronization blocked, waste of resources is relatively serious. And WebFluxyou can do asynchronous non-blocking.

② event-driven ( Event-driven), and the like Vueand Angular, as the corresponding dynamic changes in all the associated value.

③ SpringMVCprojects are required to run on Servlet containers such as Tomcat, Jetty... but now WebFluxnot only run on traditional Servlet container (support required Servlet3.1), but also to run in support NIOof Nettyand Undertowin.

Two, WebFlux entry

① the introduction of WebFluxdependency, introduced webfluxnot introduced spring-boot-starter-webbecause of spring-boot-starter-weba higher priority.

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

② start-up mode by default Netty8080 port.

③ coding

Because if it is to achieve asynchronous non-blocking effect, the database should be replaced innoDBdatabase, where static variable simulation database.

public class User {
    private long id ;
    private String name;
}   

@Service
public class UserService {

    private static final Map<Integer, User> dataMap = new HashMap<>();

    static {
        dataMap.put(1,new User(1,"a"));
        dataMap.put(2,new User(2,"b"));
        dataMap.put(3,new User(3,"c"));
        dataMap.put(4,new User(4,"d"));
    }

    /**
     * 返回所有用户
     */
    public Flux<User> getAllUser(){
        Collection<User> users = dataMap.values();
        return Flux.fromIterable(users);
    }

    /**
     * 返回具体用户
     */
    public Mono<User> getUserById(int id){
        User user = dataMap.get(id);
        return Mono.justOrEmpty(user);
    }
}

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

    @Autowired
    UserService userService;

    /**
     * 返回指定用户额
     */
    @RequestMapping("/{id}")
    public Mono<User> getUserById(@PathVariable int id){
        return userService.getUserById(id);
    }

    /**
     * 返回所有用户
     */
    @RequestMapping("/all")
    public Flux<User> getAllUsers(){
        return userService.getAllUser();
    }

    /**
     * 延迟返回用户
     * produces控制服务器返回客户端的格式
     */
    @RequestMapping(value = "/delay",produces = MediaType.APPLICATION_STREAM_JSON_VALUE)
    public Flux<User> getAllUsersDelay(){
        return userService.getAllUser().delayElements(Duration.ofSeconds(2));
    }
}

④ Description

MonoIt represented by 0 or asynchronous comprising sequence elements, as a single object

FluxIt represents the asynchronous sequence comprising 0 to N elements, the list of objects array

Spring WebFluxApplication is not strictly dependent on Servlet API, and therefore they can not be used as warfile deployment can not use the src/main/webappdirectory.

Spring WebFluxTemplate supports a variety of techniques, including Thymeleaf, FreeMarker.

Three, Mono, Flux interpretation of API