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spring webflux响应式编程使用详解

作者:yysx

webflux,即响应式编程,响应式编程是一种用于处理异步数据流和事件的编程范式,spring webflux是spring在5.0版本后提供的一套响应式编程风格的web开发框架,本文给大家详细讲讲spring webflux响应式编程的使用,需要的朋友可以参考下

一 、响应式编程

响应式编程(reactive programming)是一种基于数据流(data stream)和变化传递(propagation of change)的声明式(declarative)的编程范式

(1)数据流

将要处理的数据抽象成流

通用的流式处理:

生产者产生数据,对数据进行中间处理,消费者拿到数据消费。

(2)变化传递

● 在命令式编程(我们的日常编程模式)下,式子a=b+c,这就意味着a的值是由b和c计算出来的。如果b或者c后续有变化,不会影响到a的值。

● 在响应式编程下,式子a:=b+c,这就意味着a的值是由b和c计算出来的。但如果b或者c的值后续有变化,会影响到a的值。

(3)声明式

通过API来处理数据流中的数据。

适用场景:异步非阻塞。响应式系统具有某些特性,使其成为低延迟、高吞吐量工作负载的理想选择。

比如:

一个日志监控系统,我们的前端页面将不再需要通过“命令式”的轮询的方式不断向服务器请求数据然后进行更新,而是在建立好通道之后,数据流从系统源源不断流向页面,从而展现实时的指标变化曲线;

一个社交平台,朋友的动态、点赞和留言不是手动刷出来的,而是当后台数据变化的时候自动体现到界面上的。

二 、响应式流

响应式流(Reactive Streams)通过定义一组实体,接口和互操作方法,给出了实现异步非阻塞背压的标准。第三方遵循这个标准来实现具体的解决方案,常见的有Reactor,RxJava,Akka Streams,Ratpack等。

常见的响应流库简介

(1)JDK9响应式流:

Publisher:发布者,数据来源,又称生产者。

Subscriber:订阅者,数据目的地,又称消费者。

Processor:发布者和订阅者之间处理数据。

(2)Reactor响应式流库

发布者:Mono(返回0或1个元素)、Flux(返回0~n个元素)。

订阅者:Spring框架来完成。

背压:

Backpressure

在异步场景中,被观察者发送事件的速度远远快于观察者的处理速度情况下,一种告知上游的被观察者降低发送速度的策略。

生产者和消费者模式下,如果生产者生产的消费多了,消费者消费不过来,就容易被压垮了。

借助背压,消费者可以告诉生产者自己需要多少量的数据。

响应式流=异步非阻塞+流量控制。

三、Spring WebFlux

Spring提供了两条并行的技术栈,一条是基于Servlet API的Spring MVC和Spring Data,另一个条是完整的响应式栈,包括Spring WebFlux和Spring Data’s reactive repositories。

在这里插入图片描述

SpringBoot提供了自动配置的Spring Webflux,简化了响应式web应用的开发。

1、整合Webflux

pom引入依赖:

 <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>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

启动类添加@EnableWebFlux。

两种方式:

(1)基于注解

@RestController
@RequestMapping("/user")
public class MyController {
    
    @GetMapping("/list")
    public Flux<User> getList(){
        return Flux.fromIterable(list.stream().filter(k->{
           return k.getId()>3;
        }).collect(Collectors.toList()));
    }
    
    @GetMapping("/{id}")
    public Mono<User> getUser(@PathVariable Long userId) {
        return this.userRepository.findById(userId);
    }
}

(2)函数式

使用handler代替controller,做流的处理。

引入路由,类似SpringMVC中的@RequestMapping。

@Component
public class UserHandler {

    @Resource
    UserServiceImpl userService;
    
    public Mono<ServerResponse> getList(ServerRequest serverRequest){
        Flux<User> userFlux=userService.getList();
        return ServerResponse.ok().body(userFlux, User.class);
    }
}

@Configuration(proxyBeanMethods = false)
public class UserRouting {

    @Bean
    public RouterFunction<ServerResponse> monoRouterFunction(UserHandler userHandler){
        return RouterFunctions
                .route(GET("/user/list"),userHandler::getList)
                .andRoute(GET("/hello").and(accept(TEXT_PLAIN)),userHandler::hello)
                .andRoute(GET("/hello/stream").and(accept(APPLICATION_STREAM_JSON)),userHandler::helloStream);
    }
}

启动后,可以看到使用的是内置的netty。

访问http://localhost:20001/user/list 即可。

   @GetMapping("list/getStringSleep")
    public Mono<String> getStringSleep() {
        log.info("invoke start");
        Mono<String> s=Mono.fromSupplier(()->createStr());
        log.info("invoke end");
        return s;
    }

   private String createStr() {
        try {
            TimeUnit.SECONDS.sleep(5);
            System.out.println("sleep");
        } catch (InterruptedException e) {
        }
        return "some string";
    }

先执行invoke start invoke end 再执行异步流处理中的sleep日志。

2022-02-18 13:47:26.364  INFO 61992 --- [ctor-http-nio-2] com.example.controller.MyController      : invoke start
2022-02-18 13:47:26.366  INFO 61992 --- [ctor-http-nio-2] com.example.controller.MyController      : invoke end
2022-02-18 13:47:26.369 DEBUG 61992 --- [ctor-http-nio-2] o.s.w.r.r.m.a.ResponseBodyResultHandler  : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Using 'text/html' given [text/html, application/xhtml+xml, image/avif, image/webp, image/apng, application/xml;q=0.9, application/signed-exchange;v=b3;q=0.9, */*;q=0.8] and supported [text/plain;charset=UTF-8, text/event-stream, text/plain;charset=UTF-8, */*]
2022-02-18 13:47:26.369 DEBUG 61992 --- [ctor-http-nio-2] o.s.w.r.r.m.a.ResponseBodyResultHandler  : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] 0..1 [java.lang.String]
sleep
2022-02-18 13:47:31.375 TRACE 61992 --- [ctor-http-nio-2] o.s.core.codec.CharSequenceEncoder       : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Writing "some string"
2022-02-18 13:47:31.376 DEBUG 61992 --- [ctor-http-nio-2] r.n.http.server.HttpServerOperations     : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Decreasing pending responses, now 0
2022-02-18 13:47:31.377 DEBUG 61992 --- [ctor-http-nio-2] r.n.http.server.HttpServerOperations     : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Last HTTP packet was sent, terminating the channel
2022-02-18 13:47:31.377 TRACE 61992 --- [ctor-http-nio-2] o.s.w.s.adapter.HttpWebHandlerAdapter    : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Completed 200 OK, headers={masked}
2022-02-18 13:47:31.377 TRACE 61992 --- [ctor-http-nio-2] o.s.h.s.r.ReactorHttpHandlerAdapter      : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Handling completed
2022-02-18 13:47:31.377 DEBUG 61992 --- [ctor-http-nio-2] r.n.http.server.HttpServerOperations     : [fceca854-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Last HTTP response frame
2022-02-18 13:47:31.378 TRACE 61992 --- [ctor-http-nio-2] reactor.netty.channel.ChannelOperations  : [fceca854, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:53707] Disposing ChannelOperation from a channel

2、事件推送

Server-Sent Event(SSEs)

 @GetMapping(value = "push",produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<String> push() {
        log.info("push start");
        Flux<String> result= Flux.fromStream(IntStream.range(1,5).mapToObj(i->{
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
            }
            return "push data--" + i;
        }));
        log.info("push end");
        return  result;
    }

在浏览器中执行http://localhost:8080/demo/push,在服务器终端可以看到日志,已经执行完成。但此时页面上的推送还在进行中。

在这里插入图片描述

从浏览器的监控可以看到,浏览器接收的是一个事件流 EventStream。

在这里插入图片描述

3、实现背压

WebFlux中可以用limitRate()设置背压的限制参数。

测试代码:

其中list为内存中构造的数据集合,此处忽略。

//不使用背压 
@GetMapping(value = "list")
    public Flux<User> getList() {
        log.info("invoke start");
        Flux<User> user=Flux.fromStream(list.stream());
        log.info("invoke end");
        return user;
    }

//使用背压
    @GetMapping(value = "list/setLimit",produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<User> getListLimit() {
        log.info("invoke start");
        Flux<User> user=Flux.fromStream(list.stream()).limitRate(2);
        log.info("invoke end");
        return user;
    }

对比使用背压和不适用背压:

● 接口的总耗时

在这里插入图片描述

● 详细耗时

使用背压:

在这里插入图片描述

不使用背压:

在这里插入图片描述

浏览器接收的数据格式略有差异:

不使用背压:
[{“id”:0,“name”:“user0”},{“id”:1,“name”:“user1”},{“id”:2,“name”:“user2”},{“id”:3,“name”:“user3”},{“id”:4,“name”:“user4”},{“id”:5,“name”:“user5”}]

使用背压:

data:{“id”:0,“name”:“user0”}

data:{“id”:1,“name”:“user1”}

data:{“id”:2,“name”:“user2”}

data:{“id”:3,“name”:“user3”}

data:{“id”:4,“name”:“user4”}

data:{“id”:5,“name”:“user5”}

四、配置数据源(以mysql为例)

我们最常使用的 JDBC 其实是同步的,而我们使用 WebFlux 是为了通过异步的方式来提高服务端的响应效率,WebFlux 虽然实现了异步,但是由于 JDBC 还是同步的,而大部分应用都是离不开数据库的,所以其实效率本质上还是没有提升。

常见的异步JDBC有:ADAB、R2DBC。

下面以R2DBC为例,介绍webflux配置mysql。

1、CRUD

● pom引入

   <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-data-r2dbc</artifactId>
    </dependency>
    <dependency>
      <groupId>dev.miku</groupId>
      <artifactId>r2dbc-mysql</artifactId>
    </dependency>

● yaml配置数据源地址

当然,使用java config的方式配置也可以。

spring:
  r2dbc:
    url: r2dbcs:mysql://localhost:3306/database?sslMode=DISABLED
    username: 
    password:

注意,这里url中的数据库连接协议不在是jdbc,而是r2dbcs

● 操作数据

这里有两种方式,都可以实现。

//方法一:通过ReactiveCrudRepository

//类似DAO
public interface UserRepository extends ReactiveCrudRepository<User,Long> {
}

//在Controller中注入,并使用。

@Resource
UserRepository userRepository;

@GetMapping("/list")
public Flux<User> getListFromDB(){
     return userRepository.findAll();
}

//方法二:使用 DatabaseClient

@Resource
DatabaseClient databaseClient;

@GetMapping("/{id}")
public Mono<Map<String,Object>> getDetail(@PathVariable("id") Integer id){
       return databaseClient.sql("select * from user where id="+id).fetch().one();
}

2、R2DBC

Reactive Relational Database Connectivity,是一个使用响应式驱动集成关系型数据库的孵化器。Spring Data R2DBC运用熟悉的Spring抽象和repository支持R2DBC。

(1)如何体现异步?

测试代码:

		@GetMapping("/{id}")
    public Mono<Map<String,Object>> getDetail(@PathVariable("id") Integer id){
        log.info("invoke start");
        Mono<Map<String,Object>> map= databaseClient.sql("select * from user where id="+id).fetch().one();
        log.info("invoke end");
        return map;
    }

浏览器请求 http://localhost:20001/demo/1,从下面的日志可以看出,日志中invoke start、invoke end相继执行,后续才建立连接,进行数据库查询操作。


2022-02-11 10:39:36.108  INFO 15483 --- [ctor-http-nio-2] com.example.controller.MyController      : invoke start
2022-02-11 10:39:36.108  INFO 15483 --- [ctor-http-nio-2] com.example.controller.MyController      : invoke end
2022-02-11 10:39:36.109 DEBUG 15483 --- [ctor-http-nio-2] io.r2dbc.pool.ConnectionPool             : Obtaining new connection from the driver
2022-02-11 10:39:36.110 DEBUG 15483 --- [ctor-http-nio-2] o.s.r2dbc.core.DefaultDatabaseClient     : Executing SQL statement [select * from user where id=1]
2022-02-11 10:39:36.110 TRACE 15483 --- [ctor-http-nio-2] o.s.r2dbc.core.DefaultDatabaseClient     : Expanded SQL [select * from user where id=1]
2022-02-11 10:39:36.111 DEBUG 15483 --- [ctor-http-nio-2] dev.miku.r2dbc.mysql.MySqlConnection     : Create a simple statement provided by text query
2022-02-11 10:39:36.111 DEBUG 15483 --- [ctor-http-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Request: SimpleQueryMessage{sql=REDACTED}
2022-02-11 10:39:36.112 TRACE 15483 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0x42250dba, L:/127.0.0.1:49383 - R:localhost/127.0.0.1:3306] READ: 121B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 01 00 00 01 02 28 00 00 02 03 64 65 66 06 66 61 |.....(....def.fa|
|00000010| 6d 69 6c 79 04 75 73 65 72 04 75 73 65 72 02 69 |mily.user.user.i|
|00000020| 64 02 69 64 0c 3f 00 0b 00 00 00 03 00 00 00 00 |d.id.?..........|
|00000030| 00 2c 00 00 03 03 64 65 66 06 66 61 6d 69 6c 79 |.,....def.family|
|00000040| 04 75 73 65 72 04 75 73 65 72 04 6e 61 6d 65 04 |.user.user.name.|
|00000050| 6e 61 6d 65 0c 2d 00 90 01 00 00 fd 00 00 00 00 |name.-..........|
|00000060| 00 09 00 00 04 01 31 06 e5 bc a0 e4 b8 89 07 00 |......1.........|
|00000070| 00 05 fe 00 00 22 00 00 00                      |....."...       |
+--------+-------------------------------------------------+----------------+
2022-02-11 10:39:36.113 DEBUG 15483 --- [actor-tcp-nio-2] d.m.r.mysql.client.MessageDuplexCodec    : Decode context change to DecodeContext-Result
2022-02-11 10:39:36.113 DEBUG 15483 --- [actor-tcp-nio-2] d.m.r.m.m.server.MetadataDecodeContext   : Respond a metadata bundle by filled-up
2022-02-11 10:39:36.113 DEBUG 15483 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Response: SyntheticMetadataMessage{completed=false, messages=[DefinitionMetadataMessage{database='family', table='user' (origin:'user'), column='id' (origin:'id'), collationId=63, size=11, type=3, definitions=0, decimals=0}, DefinitionMetadataMessage{database='family', table='user' (origin:'user'), column='name' (origin:'name'), collationId=45, size=400, type=253, definitions=0, decimals=0}], eof=null}
2022-02-11 10:39:36.113 DEBUG 15483 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Response: RowMessage(encoded)
2022-02-11 10:39:36.113 DEBUG 15483 --- [actor-tcp-nio-2] d.m.r.mysql.client.MessageDuplexCodec    : Decode context change to DecodeContext-Command
2022-02-11 10:39:36.114 DEBUG 15483 --- [actor-tcp-nio-2] io.r2dbc.pool.PooledConnection           : Releasing connection
2022-02-11 10:39:36.114 TRACE 15483 --- [actor-tcp-nio-2] o.s.http.codec.json.Jackson2JsonEncoder  : [8cf12dd9-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:49377] Encoding [{id=1, name=张三}]
2022-02-11 10:39:36.115 TRACE 15483 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0x42250dba, L:/127.0.0.1:49383 - R:localhost/127.0.0.1:3306] READ COMPLETE
2022-02-11 10:39:36.115 DEBUG 15483 --- [ctor-http-nio-2] r.n.http.server.HttpServerOperations     : [8cf12dd9-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:49377] Decreasing pending responses, now 0
2022-02-11 10:39:36.116 TRACE 15483 --- [ctor-http-nio-2] o.s.w.s.adapter.HttpWebHandlerAdapter    : [8cf12dd9-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:49377] Completed 200 OK, headers={masked}
2022-02-11 10:39:36.116 TRACE 15483 --- [ctor-http-nio-2] o.s.h.s.r.ReactorHttpHandlerAdapter      : [8cf12dd9-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:49377] Handling completed
2022-02-11 10:39:36.116 DEBUG 15483 --- [ctor-http-nio-2] r.n.http.server.HttpServerOperations     : [8cf12dd9-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:49377] Last HTTP response frame
2022-02-11 10:39:36.116 DEBUG 15483 --- [ctor-http-nio-2] r.n.http.server.HttpServerOperations     : [8cf12dd9-2, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:49377] Last HTTP packet was sent, terminating the channel
2022-02-11 10:39:36.116 TRACE 15483 --- [ctor-http-nio-2] reactor.netty.channel.ChannelOperations  : [8cf12dd9, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:49377] Disposing ChannelOperation from a channel

(2)如何使用事务?

非响应式事务:
代码在同一线程上执行,默认同步的方式实现。采用ThreadLocal的方式,保存连接和会话信息。

响应式事务:
代码在不同线程上执行,使用Context来代替ThreadLocal。
类似一个不可变的Map<Object, Object>,采用CopyOnWrite策略,绑定在每一个订阅者上。

两种使用方式:
声明式事务

Spring 5.2后,已经支持响应式事务,可以直接使用@Transactional注解。

   @Resource
    private DatabaseClient db;
    @Override
    @Transactional
    public Mono<Void> insertRows() {     
        return db.sql("INSERT INTO user (id,name) VALUES(110, 'aaa')")
                .fetch().rowsUpdated()
                .then(db.sql("INSERT INTO user (id,name) VALUES(111, 'aaa')")
                        .then());
    }

主要执行日志:


2022-02-14 10:59:06.077 DEBUG 22687 --- [ctor-http-nio-2] o.s.r.c.R2dbcTransactionManager          : Creating new transaction with name [com.example.service.UserServiceImpl.insertRows]: PROPAGATION_REQUIRED,ISOLATION_DEFAULT
2022-02-14 10:59:06.077 DEBUG 22687 --- [ctor-http-nio-2] io.r2dbc.pool.ConnectionPool             : Obtaining new connection from the driver
2022-02-14 10:59:06.078 DEBUG 22687 --- [ctor-http-nio-2] o.s.r.c.R2dbcTransactionManager          : Acquired Connection [MonoRetry] for R2DBC transaction
2022-02-14 10:59:06.078 DEBUG 22687 --- [ctor-http-nio-2] o.s.r.c.R2dbcTransactionManager          : Switching R2DBC Connection [PooledConnection[dev.miku.r2dbc.mysql.MySqlConnection@4f99ad97]] to manual commit
2022-02-14 10:59:06.078 DEBUG 22687 --- [ctor-http-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Request: SimpleQueryMessage{sql=REDACTED}
		+-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 03 53 45 54 20 61 75 74 6f 63 6f 6d 6d 69 74 3d |.SET autocommit=|
|00000010| 30                                              |0               |
+--------+-------------------------------------------------+----------------+


		+-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 03 42 45 47 49 4e                               |.BEGIN          |
+--------+-------------------------------------------------+----------------+
2022-02-14 10:59:06.080 TRACE 22687 --- [actor-tcp-nio-2] o.s.t.i.TransactionInterceptor           : Getting transaction for [com.example.service.UserServiceImpl.insertRows]
2022-02-14 10:59:06.081 DEBUG 22687 --- [actor-tcp-nio-2] o.s.r2dbc.core.DefaultDatabaseClient     : Executing SQL statement [INSERT INTO user (id,name) VALUES(110, 'aaa')]
2022-02-14 10:59:06.081 TRACE 22687 --- [actor-tcp-nio-2] o.s.r2dbc.core.DefaultDatabaseClient     : Expanded SQL [INSERT INTO user (id,name) VALUES(110, 'aaa')]
+-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 03 49 4e 53 45 52 54 20 49 4e 54 4f 20 75 73 65 |.INSERT INTO use|
|00000010| 72 20 28 69 64 2c 6e 61 6d 65 29 20 56 41 4c 55 |r (id,name) VALU|
|00000020| 45 53 28 31 31 30 2c 20 27 61 61 61 27 29       |ES(110, 'aaa')  |
+--------+-------------------------------------------------+----------------+
2022-02-14 10:59:06.082 DEBUG 22687 --- [actor-tcp-nio-2] o.s.r2dbc.core.DefaultDatabaseClient     : Executing SQL statement [INSERT INTO user (id,name) VALUES(111, 'aaa')]
2022-02-14 10:59:06.082 TRACE 22687 --- [actor-tcp-nio-2] o.s.r2dbc.core.DefaultDatabaseClient     : Expanded SQL [INSERT INTO user (id,name) VALUES(111, 'aaa')]
2022-02-14 10:59:06.082 DEBUG 22687 --- [actor-tcp-nio-2] dev.miku.r2dbc.mysql.MySqlConnection     : Create a simple statement provided by text query
2022-02-14 10:59:06.082 DEBUG 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Request: SimpleQueryMessage{sql=REDACTED}
2022-02-14 10:59:06.083 TRACE 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0xc62edac7, L:/127.0.0.1:61272 - R:localhost/127.0.0.1:3306] WRITE: 46B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 03 49 4e 53 45 52 54 20 49 4e 54 4f 20 75 73 65 |.INSERT INTO use|
|00000010| 72 20 28 69 64 2c 6e 61 6d 65 29 20 56 41 4c 55 |r (id,name) VALU|
|00000020| 45 53 28 31 31 31 2c 20 27 61 61 61 27 29       |ES(111, 'aaa')  |
+--------+-------------------------------------------------+----------------+
2022-02-14 10:59:06.083 DEBUG 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.MessageDuplexCodec    : Decode context change to DecodeContext-Command
2022-02-14 10:59:06.083 TRACE 22687 --- [actor-tcp-nio-2] o.s.t.i.TransactionInterceptor           : Completing transaction for [com.example.service.UserServiceImpl.insertRows]
2022-02-14 10:59:06.083 DEBUG 22687 --- [actor-tcp-nio-2] o.s.r.c.R2dbcTransactionManager          : Initiating transaction commit
2022-02-14 10:59:06.083 DEBUG 22687 --- [actor-tcp-nio-2] o.s.r.c.R2dbcTransactionManager          : Committing R2DBC transaction on Connection [PooledConnection[dev.miku.r2dbc.mysql.MySqlConnection@4f99ad97]]
2022-02-14 10:59:06.083 DEBUG 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Request: SimpleQueryMessage{sql=REDACTED}
2022-02-14 10:59:06.084 TRACE 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0xc62edac7, L:/127.0.0.1:61272 - R:localhost/127.0.0.1:3306] WRITE: 4B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 07 00 00 00                                     |....            |
+--------+-------------------------------------------------+----------------+
2022-02-14 10:59:06.084 TRACE 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0xc62edac7, L:/127.0.0.1:61272 - R:localhost/127.0.0.1:3306] WRITE: 7B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 03 43 4f 4d 4d 49 54                            |.COMMIT         |
+--------+-------------------------------------------------+----------------+

2022-02-14 10:59:06.098 TRACE 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0xc62edac7, L:/127.0.0.1:61272 - R:localhost/127.0.0.1:3306] WRITE: 17B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 03 53 45 54 20 61 75 74 6f 63 6f 6d 6d 69 74 3d |.SET autocommit=|
|00000010| 31                                              |1               |

2022-02-14 10:59:06.099 DEBUG 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.MessageDuplexCodec    : Decode context change to DecodeContext-Command
2022-02-14 10:59:06.099 DEBUG 22687 --- [actor-tcp-nio-2] o.s.r.c.R2dbcTransactionManager          : Releasing R2DBC Connection [PooledConnection[dev.miku.r2dbc.mysql.MySqlConnection@4f99ad97]] after transaction
2022-02-14 10:59:06.099 DEBUG 22687 --- [actor-tcp-nio-2] io.r2dbc.pool.PooledConnection           : Releasing connection


若执行异常,需要回滚时,日志如下:
2022-02-14 11:10:31.410 DEBUG 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Response: ErrorMessage{errorCode=1062, sqlState='23000', errorMessage='Duplicate entry '110' for key 'PRIMARY''}
2022-02-14 11:10:31.419 TRACE 22687 --- [actor-tcp-nio-2] o.s.t.i.TransactionInterceptor           : Completing transaction for [com.example.service.UserServiceImpl.insertRows] after exception: org.springframework.dao.DataIntegrityViolationException: execute; SQL [INSERT INTO user (id,name) VALUES(110, 'aaa')]; Duplicate entry '110' for key 'PRIMARY'; nested exception is io.r2dbc.spi.R2dbcDataIntegrityViolationException: [1062] [23000] Duplicate entry '110' for key 'PRIMARY'
2022-02-14 11:10:31.421 DEBUG 22687 --- [actor-tcp-nio-2] o.s.r.c.R2dbcTransactionManager          : Initiating transaction rollback
2022-02-14 11:10:31.421 DEBUG 22687 --- [actor-tcp-nio-2] o.s.r.c.R2dbcTransactionManager          : Rolling back R2DBC transaction on Connection [PooledConnection[dev.miku.r2dbc.mysql.MySqlConnection@47e30501]]
2022-02-14 11:10:31.421 DEBUG 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : Request: SimpleQueryMessage{sql=REDACTED}
2022-02-14 11:10:31.422 TRACE 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0x55800452, L:/127.0.0.1:61274 - R:localhost/127.0.0.1:3306] WRITE: 4B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 09 00 00 00                                     |....            |
+--------+-------------------------------------------------+----------------+
2022-02-14 11:10:31.422 TRACE 22687 --- [actor-tcp-nio-2] d.m.r.mysql.client.ReactorNettyClient    : [id: 0x55800452, L:/127.0.0.1:61274 - R:localhost/127.0.0.1:3306] WRITE: 9B
         +-------------------------------------------------+
         |  0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f |
+--------+-------------------------------------------------+----------------+
|00000000| 03 52 4f 4c 4c 42 41 43 4b                      |.ROLLBACK       |
+--------+-------------------------------------------------+----------------+

具体源码查看,在TransactionAspectSupport类中。

其中,根据ReactiveTransactionManager接口类型,决定走响应式事务或非响应式事务。下面在编程式事务中提到的R2dbcTransactionManager就实现了ReactiveTransactionManager接口。

   protected Object invokeWithinTransaction(Method method, @Nullable Class<?> targetClass, final TransactionAspectSupport.InvocationCallback invocation) throws Throwable {
        TransactionAttributeSource tas = this.getTransactionAttributeSource();
        TransactionAttribute txAttr = tas != null ? tas.getTransactionAttribute(method, targetClass) : null;
        TransactionManager tm = this.determineTransactionManager(txAttr);
        if (this.reactiveAdapterRegistry != null && tm instanceof ReactiveTransactionManager) {
            boolean isSuspendingFunction = KotlinDetector.isSuspendingFunction(method);
            boolean hasSuspendingFlowReturnType = isSuspendingFunction && "kotlinx.coroutines.flow.Flow".equals((new MethodParameter(method, -1)).getParameterType().getName());
            if (isSuspendingFunction && !(invocation instanceof TransactionAspectSupport.CoroutinesInvocationCallback)) {
                throw new IllegalStateException("Coroutines invocation not supported: " + method);
            } else {
                TransactionAspectSupport.CoroutinesInvocationCallback corInv = isSuspendingFunction ? (TransactionAspectSupport.CoroutinesInvocationCallback)invocation : null;
                TransactionAspectSupport.ReactiveTransactionSupport txSupport = (TransactionAspectSupport.ReactiveTransactionSupport)this.transactionSupportCache.computeIfAbsent(method, (key) -> {
                    Class<?> reactiveType = isSuspendingFunction ? (hasSuspendingFlowReturnType ? Flux.class : Mono.class) : method.getReturnType();
                    ReactiveAdapter adapter = this.reactiveAdapterRegistry.getAdapter(reactiveType);
                    if (adapter == null) {
                        throw new IllegalStateException("Cannot apply reactive transaction to non-reactive return type: " + method.getReturnType());
                    } else {
                        return new TransactionAspectSupport.ReactiveTransactionSupport(adapter);
                    }
                });
                TransactionAspectSupport.InvocationCallback callback = invocation;
                if (corInv != null) {
                    callback = () -> {
                        return CoroutinesUtils.invokeSuspendingFunction(method, corInv.getTarget(), corInv.getArguments());
                    };
                }

                Object result = txSupport.invokeWithinTransaction(method, targetClass, callback, txAttr, (ReactiveTransactionManager)tm);
                if (corInv != null) {
                    Publisher<?> pr = (Publisher)result;
                    return hasSuspendingFlowReturnType ? TransactionAspectSupport.KotlinDelegate.asFlow(pr) : TransactionAspectSupport.KotlinDelegate.awaitSingleOrNull(pr, corInv.getContinuation());
                } else {
                    return result;
                }
            }
        } else {
        
        //略
        }
 }

编程式事务

与声明式事务相比,编程式事务使用的较少,因为配置相对繁琐。但可以帮助理解执行逻辑。

 @Resource
    ConnectionFactory connectionFactory;
    
    @Override
    public Mono<Void> insertRows() {
        ReactiveTransactionManager tm=new R2dbcTransactionManager(connectionFactory);
        DatabaseClient db=DatabaseClient.create(connectionFactory);

        TransactionalOperator transactionalOperator=TransactionalOperator.create(tm);
        
        return db.sql("INSERT INTO user (id,name) VALUES(119, 'bbb')")
                .fetch().rowsUpdated()
                .then(db.sql("INSERT INTO user (id,name) VALUES(111, 'aaa')")
                        .then())
                .as(transactionalOperator::transactional);
    }

R2dbcTransactionManager:响应式事务管理器。
DatabaseClient:客户端使用R2DBC驱动程序提供对SQL数据库的访问。
TransactionalOperator:事务运算符将所有上游R2DBC发布者与事务上下文相关联。

(3)线程池配置

为了提升数据库的执行效率,减少建立连接的开销,一般数据库连接都会有连接池的概念,同样的r2dbc也有一个叫做r2dbc-pool的连接池。

<dependency>
 <groupId>io.r2dbc</groupId>
 <artifactId>r2dbc-pool</artifactId>
 <version>${version}</version>
</dependency>

五、远程调用

Spring webflux提供WebClient进行远程调用,这里使用webclient做示例,okhttp可以后面作补充。

简单服务

 WebClient webClient= WebClient.builder().build();
 @GetMapping("/remote/webClient")
    public Flux<User> queryByWebclient(){
        log.info("invoke start");
        Flux<User> list=webClient.get().uri(url).retrieve().bodyToFlux(User.class);
        log.info("invoke end");
        return list;
    }

主要执行流程:

main thread 打印 invoke start invoke end

创建线程池,进行远程调用,初始化pipeline。

连接调用url,建立channel。

接收响应,释放channel。


2022-02-15 13:58:32.231 DEBUG 27846 --- [ctor-http-nio-5] s.w.r.r.m.a.RequestMappingHandlerMapping : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Mapped to com.example.controller.MyController#queryByWebclient()
2022-02-15 13:58:32.231  INFO 27846 --- [ctor-http-nio-5] com.example.controller.MyController      : invoke start
2022-02-15 13:58:32.232  INFO 27846 --- [ctor-http-nio-5] com.example.controller.MyController      : invoke end
2022-02-15 13:58:32.234 DEBUG 27846 --- [ctor-http-nio-5] o.s.w.r.r.m.a.ResponseBodyResultHandler  : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Using 'application/json' given [text/html, application/xhtml+xml, image/avif, image/webp, image/apng, application/xml;q=0.9, application/signed-exchange;v=b3;q=0.9, */*;q=0.8] and supported [application/json, application/*+json, application/x-ndjson, text/event-stream]
2022-02-15 13:58:32.234 DEBUG 27846 --- [ctor-http-nio-5] o.s.w.r.r.m.a.ResponseBodyResultHandler  : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] 0..N [com.example.model.User]
2022-02-15 13:58:32.236 TRACE 27846 --- [ctor-http-nio-5] o.s.w.r.f.client.ExchangeFunctions       : [6c2270b1] HTTP GET http://localhost:8082/web/test?str=webclient, headers={}
2022-02-15 13:58:32.247 DEBUG 27846 --- [ctor-http-nio-5] r.n.resources.PooledConnectionProvider   : [ae492444] Created a new pooled channel, now: 0 active connections, 0 inactive connections and 0 pending acquire requests.
2022-02-15 13:58:32.247 DEBUG 27846 --- [ctor-http-nio-5] reactor.netty.transport.TransportConfig  : [ae492444] Initialized pipeline DefaultChannelPipeline{(reactor.left.httpCodec = io.netty.handler.codec.http.HttpClientCodec), (reactor.left.httpDecompressor = io.netty.handler.codec.http.HttpContentDecompressor), (reactor.right.reactiveBridge = reactor.netty.channel.ChannelOperationsHandler)}
2022-02-15 13:58:32.252 DEBUG 27846 --- [ctor-http-nio-5] r.netty.transport.TransportConnector     : [ae492444] Connecting to [localhost/127.0.0.1:8082].
2022-02-15 13:58:32.252 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Registering 。 release on close event for channel
2022-02-15 13:58:32.252 DEBUG 27846 --- [ctor-http-nio-5] r.n.resources.PooledConnectionProvider   : [ae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Channel connected, now: 1 active connections, 0 inactive connections and 0 pending acquire requests.
2022-02-15 13:58:32.252 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] onStateChange(PooledConnection{channel=[id: 0xae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082]}, [connected])
2022-02-15 13:58:32.252 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] onStateChange(GET{uri=/, connection=PooledConnection{channel=[id: 0xae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082]}}, [configured])
2022-02-15 13:58:32.253 DEBUG 27846 --- [ctor-http-nio-5] r.netty.http.client.HttpClientConnect    : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Handler is being applied: {uri=http://localhost:8082/web/test?str=webclient, method=GET}
2022-02-15 13:58:32.253 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] onStateChange(GET{uri=/web/test?str=webclient, connection=PooledConnection{channel=[id: 0xae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082]}}, [request_prepared])
2022-02-15 13:58:32.254 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] onStateChange(GET{uri=/web/test?str=webclient, connection=PooledConnection{channel=[id: 0xae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082]}}, [request_sent])
2022-02-15 13:58:33.384 DEBUG 27846 --- [ctor-http-nio-5] r.n.http.client.HttpClientOperations     : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Received response (auto-read:false) : [Date=Tue, 15 Feb 2022 05:58:33 GMT, content-length=0]
2022-02-15 13:58:33.384 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] onStateChange(GET{uri=/web/test?str=webclient, connection=PooledConnection{channel=[id: 0xae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082]}}, [response_received])
2022-02-15 13:58:33.384 TRACE 27846 --- [ctor-http-nio-5] o.s.w.r.f.client.ExchangeFunctions       : [6c2270b1] [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Response 200 OK, headers={masked}
2022-02-15 13:58:33.385 DEBUG 27846 --- [ctor-http-nio-5] reactor.netty.channel.FluxReceive        : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] FluxReceive{pending=0, cancelled=false, inboundDone=false, inboundError=null}: subscribing inbound receiver
2022-02-15 13:58:33.386 DEBUG 27846 --- [ctor-http-nio-5] r.n.http.client.HttpClientOperations     : [ae492444-1, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Received last HTTP packet
2022-02-15 13:58:33.387 TRACE 27846 --- [ctor-http-nio-5] reactor.netty.channel.ChannelOperations  : [ae492444, L:/127.0.0.1:61048 - 
2022-02-15 13:58:33.432 TRACE 27846 --- [ctor-http-nio-5] o.s.http.codec.json.Jackson2JsonEncoder  : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Encoding [[]]
2022-02-15 13:58:33.433 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] onStateChange(GET{uri=/web/test?str=webclient, connection=PooledConnection{channel=[id: 0xae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082]}}, [response_completed])
2022-02-15 13:58:33.434 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] onStateChange(GET{uri=/web/test?str=webclient, connection=PooledConnection{channel=[id: 0xae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082]}}, [disconnecting])
2022-02-15 13:58:33.434 DEBUG 27846 --- [ctor-http-nio-5] r.n.r.DefaultPooledConnectionProvider    : [ae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Releasing channel
2022-02-15 13:58:33.434 DEBUG 27846 --- [ctor-http-nio-5] r.n.resources.PooledConnectionProvider   : [ae492444, L:/127.0.0.1:61048 - R:localhost/127.0.0.1:8082] Channel cleaned, now: 0 active connections, 1 inactive connections and 0 pending acquire requests.
2022-02-15 13:58:33.434 TRACE 27846 --- [ctor-http-nio-5] o.s.w.s.adapter.HttpWebHandlerAdapter    : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Completed 200 OK, headers={masked}
2022-02-15 13:58:33.434 TRACE 27846 --- [ctor-http-nio-5] o.s.h.s.r.ReactorHttpHandlerAdapter      : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Handling completed
2022-02-15 13:58:33.434 DEBUG 27846 --- [ctor-http-nio-5] r.n.http.server.HttpServerOperations     : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Last HTTP response frame
2022-02-15 13:58:33.434 DEBUG 27846 --- [ctor-http-nio-5] r.n.http.server.HttpServerOperations     : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Decreasing pending responses, now 0
2022-02-15 13:58:33.434 DEBUG 27846 --- [ctor-http-nio-5] r.n.http.server.HttpServerOperations     : [7a8c56a7-1, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Last HTTP packet was sent, terminating the channel
2022-02-15 13:58:33.435 TRACE 27846 --- [ctor-http-nio-5] reactor.netty.channel.ChannelOperations  : [7a8c56a7, L:/0:0:0:0:0:0:0:1:20001 - R:/0:0:0:0:0:0:0:1:61046] Disposing ChannelOperation from a channel

首次进行远程调用,会创建一个http的客户端线程池,再次发起远程调用时,会直接使用现有线程池。

leasingStrategy:FIFO 先进先出。

evictionInterval:实例销毁的间隔 0s。

maxConnections:最大连接数,500。

maxIdleTime: 最大空闲时间

maxLifeTime: 最大存活时间

metricsEnabled: 是否启用指标

pendingAcquireMaxCount:

pendingAcquireTimeout:

Creating a new [http] client pool [PoolFactory{evictionInterval=PT0S, leasingStrategy=fifo, maxConnections=500, maxIdleTime=-1, maxLifeTime=-1, metricsEnabled=false, pendingAcquireMaxCount=1000, pendingAcquireTimeout=45000}] for [localhost:8082]

Created a new pooled channel, now: 0 active connections, 0 inactive connections and 0 pending acquire requests.

依赖服务

如果两个远程调用方法之间有彼此依赖关系,应该如何使用?比如rpcB需要使用rpcA返回的结果值做处理。

示例:

@GetMapping("/remote/webClient")
    public Flux<Integer> queryByWebclient(){
        log.info("invoke start");
        long start =System.nanoTime();
        Flux<Integer> userFlux = userService.getListDependency(0 ).flatMap(k -> userService.getListDependency(k)
        );
        userFlux.subscribe(k-> System.out.println(" controller time"+(System.nanoTime()-start)));
        log.info("invoke end");
        return userFlux;
    }
//远程调用的service
public Flux<Integer> getListDependency(Integer str) {
        Flux<Integer> list=webClient.get().uri(url+str).retrieve().bodyToFlux(Integer.class);
        list.subscribe(k-> System.out.print("service time"+new Date()));
        return list;
 }

六、与Spring MVC的比较

示例

SpringMVC方式

@GetMapping("/remote/webClient")
    public Flux<Integer> queryByWebclient(){
        log.info("invoke start");
        long start =System.nanoTime();
        Flux<Integer> userFlux = userService.getListDependency(0 ).flatMap(k -> userService.getListDependency(k)
        );
        userFlux.subscribe(k-> System.out.println(" controller time"+(System.nanoTime()-start)));
        log.info("invoke end");
        return userFlux;
    }
//远程调用的service
public Flux<Integer> getListDependency(Integer str) {
        Flux<Integer> list=webClient.get().uri(url+str).retrieve().bodyToFlux(Integer.class);
        list.subscribe(k-> System.out.print("service time"+new Date()));
        return list;
 }

日志执行结果:

在这里插入图片描述

WebFlux的响应式处理:

 @GetMapping("/list/reactor")
    public Flux<User> getListReactor(){
        log.info("enter controller");
        Flux<User> listFromDB = userService.getListByReactor();
        log.info("end controller");
        return listFromDB;
    }

@Override
    public  Flux<User> getListByReactor() {
        log.info("enter service");
        List<User> userList = new ArrayList<>();
        Set<Map.Entry<String,User>> entries =userMap.entrySet();
        entries.stream().forEach(entry->userList.add(entry.getValue()));
        Flux<User> userFlux = Flux.fromStream(() -> createStr(userList));
        log.info("end service");
        return userFlux;
    }

  private Stream<User> createStr(List<User> userList) {
        try {
            System.out.println("start sleep");
            TimeUnit.SECONDS.sleep(5);
        } catch (InterruptedException e) {
        }
        return userList.stream();
    }

执行结果:

在这里插入图片描述

小结:

1、WebFlux是异步处理的,SpringMVC是同步的,但也可以实现异步非阻塞。

2、Servlet3.1已经支持异步非阻塞了,但无论是回调或是使用CompletableFuture,代码实现起来会比较复杂。WebFlux提供的API会更加方便。Spring WebFlux在应对高并发的请求时,借助于异步IO,能够以少量而稳定的线程处理更高吞吐量的请求。

七、扩展

应用:

Gateway是基于Webflux实现的,它通过扩展HandlerMapping与WebHandler来处理用户的请求,先通过Predicate定位到Router然后在经过FilterChain的过滤处理,最后定位到下层服务。

以上就是spring webflux响应式编程使用详解的详细内容,更多关于spring webflux使用的资料请关注脚本之家其它相关文章!

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