关系数据构建反应式的spring驱动程序

2022-05-24 00:14:20

关系数据构建反应式的spring驱动程序

先说说什么是响应式
响应式编程或反应式编程（英语：Reactive programming）是一种面向数据流和变化传播的编程范式，直白的说就是：将变化的值通过数据流进行传播。

反应式架构文章
WebFlux定点推送、全推送灵活websocket运用【推】
WebFlux前后端分离 -- 数据响应式展示 【推】
webflux+redis/mongodb提供响应式API【推】
WebFlux是什么呢
WebFlux 模块的名称是 spring-webflux，名称中的 Flux 来源于 Reactor 中的类 Flux。Spring webflux 有一个全新的非堵塞的函数式 Reactive Web 框架，可以用来构建异步的、非堵塞的、事件驱动的服务，在伸缩性方面表现非常好。

spring-webflux 模块。该模块包含对响应式 HTTP 和 WebSocket 客户端的支持，以及对 REST，HTML 和 WebSocket 交互等程序的支持。一般来说，Spring MVC 用于同步处理，Spring Webflux 用于异步处理。

Spring Boot Webflux 有两种编程模型实现，一种类似 Spring MVC 注解方式，另一种是基于 Reactor 的响应式方式。

R2DBC是什么？
响应式关系数据库连接的支持

主题
之前我有对非关系性数据库的响应式api实现（传送门），而今天我们要说说非关系型数据库实现。

体验spring boot  2.3.0.RC1 , 期待已久mysql  reactive 总算开始展露头角了。 今天就来整合一下springboot 和r2dbc 与mysql。主要是采用 Spring Data R2DBC ，Spring Data R2DBC对R2DBC应用了熟悉的Spring抽象和存储库支持。它使在响应式应用程序堆栈中构建使用关系数据访问技术的Spring驱动的应用程序更加容易。

POM

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
    <groupId>com.gitee.occo</groupId>
    <artifactId>occo-parent</artifactId>
    <version>2.0.0-SNAPSHOT</version>
</parent>
<artifactId>occo-sso</artifactId>
<version>0.0.1-SNAPSHOT</version>

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-r2dbc</artifactId>
    </dependency>

    <dependency>
        <groupId>dev.miku</groupId>
        <artifactId>r2dbc-mysql</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>io.projectreactor</groupId>
        <artifactId>reactor-test</artifactId>
        <scope>test</scope>
    </dependency>

    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <scope>provided</scope>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-compiler-plugin</artifactId>
            <configuration>
                <source>${java.version}</source>
                <target>${java.version}</target>
                <encoding>UTF-8</encoding>
            </configuration>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-release-plugin</artifactId>
            <configuration>
                <tagNameFormat>v@{project.version}</tagNameFormat>
                <autoVersionSubmodules>true</autoVersionSubmodules>
                <indentSize>4</indentSize>
                <useEditMode>true</useEditMode>
                <localCheckout>true</localCheckout>
            </configuration>
        </plugin>
    </plugins>
</build>


POM中的occo-parent可以替换成

<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.0.RC1</version>
<relativePath/> <!-- lookup parent from repository -->

<repositories>
    <repository>
        <id>spring-milestones</id>
        <name>Spring Milestones</name>
        <url>https://repo.spring.io/milestone</url>
    </repository>
</repositories>
<pluginRepositories>
    <pluginRepository>
        <id>spring-milestones</id>
        <name>Spring Milestones</name>
        <url>https://repo.spring.io/milestone</url>
    </pluginRepository>
</pluginRepositories>

application.yml
server:
port: 8000

spring:
application:

name: occo-sso

r2dbc:

url: r2dbc:mysql://localhost:3306/occo
username: root
password: pwd2020

logging:
level:

org.springframework.data.r2dbc: DEBUG

实现一个简单数据操作
repository：

import org.springframework.data.r2dbc.repository.Query;
import org.springframework.data.repository.reactive.ReactiveCrudRepository;
import org.springframework.stereotype.Repository;

import com.gitee.occo.sso.user.entity.User;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

@Repository
public interface UserRepository extends ReactiveCrudRepository{

@Query("SELECT * FROM user WHERE state = :state")
Flux<User> findByState(Integer state);

@Query("SELECT * FROM user WHERE username = :username")
Mono<User> findByUsername(String username);

@Query("SELECT * FROM user WHERE username LIKE :username")
Flux<User> findByUsernameLike(String username);

}
service

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.gitee.occo.sso.user.entity.User;
import com.gitee.occo.sso.user.repository.UserRepository;
import com.gitee.occo.sso.user.service.UserService;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

@Service
public class UserServiceImpl implements UserService {

@Autowired
private UserRepository userRepository;

@Override
public Mono<User> findById(Long id) {
    // TODO Auto-generated method stub
    return userRepository.findById(id);
}

@Override
public Mono<User> findByUsername(String username) {
    // TODO Auto-generated method stub
    return userRepository.findByUsername(username);
}

@Override
public Flux<User> findByUsernameLike(String username) {
    // TODO Auto-generated method stub
    return userRepository.findByUsernameLike(username);
}

}
controller:

import java.time.Duration;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.gitee.occo.sso.user.entity.User;
import com.gitee.occo.sso.user.service.UserService;

import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;

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

@Autowired
UserService userService;

@GetMapping("/findById/{id}")
public Mono<User> getUserById(@PathVariable("id")Long id){
    return userService.findById(id);
}

@GetMapping("/findByUsername")
public Mono<User> findByUsername(String username){
    return userService.findByUsername(username);
}

@GetMapping(value="/findByUsernameLike" ,produces = MediaType.APPLICATION_STREAM_JSON_VALUE)
public Flux<User> getByUsername(String username){
    return userService.findByUsernameLike(username+"%").delayElements(Duration.ofSeconds(2));
}

}
PS：produces = MediaType.APPLICATION_STREAM_JSON_VALUE  要加上，不然就会等待完成，一个请求体返回回去。

代码：传送门

原文地址https://my.oschina.net/bianxin/blog/4277900

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