spring5入门（二十七）：WebFlux实现，函数式编程模型

• 简介

1、在使用函数式编程模型操作时候，需要自己初始化服务器
2、基于函数式编程模型时候，有两个核心接口：RouterFunction（实现路由功能，请求转发给对应的 handler）和 HandlerFunction（处理请求生成响应的函数）。核心任务定义两个函数
式接口的实现并且启动需要的服务器
3、SpringWebflux 请 求 和 响 应 不 再 是 ServletRequest 和 ServletResponse ，而是ServerRequest 和 ServerResponse

• 构建springboot项目，导入依赖

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

• 实体类

public class User {

    private String name;
    
    private String gender;
    
    private Integer age;

    public void setName(String name) {
        this.name = name;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public String getGender() {
        return gender;
    }

    public Integer getAge() {
        return age;
    }

    public User() {
    }

    public User(String name, String gender, Integer age) {
        this.name = name;
        this.gender = gender;
        this.age = age;
    }

}

• 业务层接口

public interface UserService {

    //根据id查询用户
    Mono<User> getUserById(int id);

    //查询所有用户
    Flux<User> getAllUser();

    //添加用户
    Mono<Void> saveUserInfo(Mono<User> user);

}

• 业务层实现

@Repository
public class UserServiceImpl implements UserService {

    //创建map集合存储数据
    private final Map<Integer,User> users = new HashMap<>();

    public UserServiceImpl() {
        this.users.put(1,new User("lucy","nan",20));
        this.users.put(2,new User("mary","nv",30));
        this.users.put(3,new User("jack","nv",50));
    }

    //根据id查询
    @Override
    public Mono<User> getUserById(int id) {
        return Mono.justOrEmpty(this.users.get(id));
    }

    //查询多个用户
    @Override
    public Flux<User> getAllUser() {
        return Flux.fromIterable(this.users.values());
    }

    //添加用户
    @Override
    public Mono<Void> saveUserInfo(Mono<User> userMono) {
        return userMono.doOnNext(person -> {
            //向map集合里面放值
            int id = users.size()+1;
            users.put(id,person);
        }).thenEmpty(Mono.empty());
    }

}

• 控制层

public class UserHandler {

    private final UserService userService;

    // 使用构造器注入
    public UserHandler(UserService userService) {
        this.userService = userService;
    }

    //根据id查询
    public Mono<ServerResponse> getUserById(ServerRequest request) {
        //获取id值
        int userId = Integer.valueOf(request.pathVariable("id"));
        //空值处理
        Mono<ServerResponse> notFound = ServerResponse.notFound().build();
        //调用service方法得到数据
        Mono<User> userMono = this.userService.getUserById(userId);
        //把userMono进行转换返回
        //使用Reactor操作符flatMap，返回1个大流
        return userMono.flatMap(person -> ServerResponse.ok().contentType(MediaType.APPLICATION_JSON)
                                .body(fromObject(person)))
                                .switchIfEmpty(notFound);
    }

    //查询所有
    public Mono<ServerResponse> getAllUsers(ServerRequest request) {
        //调用service得到结果
        Flux<User> users = this.userService.getAllUser();
        return ServerResponse.ok().contentType(MediaType.APPLICATION_JSON).body(users,User.class);
    }

    //添加
    public Mono<ServerResponse> saveUser(ServerRequest request) {
        //得到user对象
        Mono<User> userMono = request.bodyToMono(User.class);
        return ServerResponse.ok().build(this.userService.saveUserInfo(userMono));
    }

}

• 配置路由和服务

public class Server {

    public static void main(String[] args) throws Exception{
        Server server = new Server();
        server.createReactorServer();
        System.out.println("enter to exit");
        System.in.read();
    }

    //1 创建Router路由
    public RouterFunction<ServerResponse> routingFunction() {
        //创建hanler对象
        UserService userService = new UserServiceImpl();
        UserHandler handler = new UserHandler(userService);
        //设置路由
        return RouterFunctions.route(
                // 发送请求方式，接收参数类型，要调用的方法
                GET("/users/{id}").and(accept(APPLICATION_JSON)),handler::getUserById)
                .andRoute(GET("/users").and(accept(APPLICATION_JSON)),handler::getAllUsers);
    }

    //2 创建服务器完成适配
    public void createReactorServer() {
        //路由和handler适配
        RouterFunction<ServerResponse> route = routingFunction();
        HttpHandler httpHandler = toHttpHandler(route);
        ReactorHttpHandlerAdapter adapter = new ReactorHttpHandlerAdapter(httpHandler);
        //创建服务器
        HttpServer httpServer = HttpServer.create();
        httpServer.handle(adapter).bindNow();
    }
    
}

• 启动测试
  
  

• 编写客户端

public class Client {

    public static void main(String[] args) {
        //调用服务器地址
        WebClient webClient = WebClient.create("http://127.0.0.1:61824");

        //根据id查询
        String id = "1";
        // 发送请求方式，要调用的方法，接收参数类型，返回类型
        User userresult = webClient.get().uri("/users/{id}", id)
                .accept(MediaType.APPLICATION_JSON).retrieve().bodyToMono(User.class)
                .block();
        System.out.println(userresult.getName());

        //查询所有
        Flux<User> results = webClient.get().uri("/users")
                .accept(MediaType.APPLICATION_JSON).retrieve().bodyToFlux(User.class);
        results.map(stu -> stu.getName())
                    .buffer().doOnNext(System.out::println).blockFirst();
    }

}

• 控制台

16:46:40.743 [main] DEBUG org.springframework.web.reactive.function.client.ExchangeFunctions - [2f16c6b3] HTTP GET http://127.0.0.1:61824/users/1
16:46:41.137 [main] DEBUG org.springframework.web.reactive.function.client.ExchangeFunctions - [2484f433] HTTP GET http://127.0.0.1:61824/users