springboot3+r2dbc——响应式编程实践
Posted 麒思妙想
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Spring boot3已经M1了，最近群佬们也开始蠢蠢欲动的开始整活Reactive+Spring Boot3,跟着大家的步伐，我也来整一篇工程入门，我们将用java17+Spring Boot3+r2dbc+Reactive栈来讲述，欢迎大家来讨论。（关于响应式，请大家异步到之前的文章里，有详细介绍。）
r2dbc
Reactor还有基于其之上的Spring WebFlux框架。包括vert.x，rxjava等等reactive技术。我们实际上在应用层已经有很多优秀的响应式处理框架。
但是有一个问题就是所有的框架都需要获取底层的数据，而基本上关系型数据库的底层读写都还是同步的。
为了解决这个问题，出现了两个标准，一个是oracle提出的 ADBC (Asynchronous Database Access API)，另一个就是Pivotal提出的R2DBC (Reactive Relational Database Connectivity)。
R2DBC是基于Reactive Streams标准来设计的。通过使用R2DBC，你可以使用reactive API来操作数据。
同时R2DBC只是一个开放的标准，而各个具体的数据库连接实现，需要实现这个标准。
今天我们以r2dbc-h2为例，讲解一下r2dbc在Spring webFlux中的使用。
工程依赖
以下是 pom.xml清单
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>3.0.0-M1</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>wang.datahub</groupId>
<artifactId>springboot3demo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot3demo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>17</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-r2dbc</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-redis-reactive</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-rest</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-groovy-templates</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-hateoas</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-webflux</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-configuration-processor</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-devtools</artifactId>
</dependency>
<dependency>
<groupId>io.r2dbc</groupId>
<artifactId>r2dbc-h2</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</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>
</dependency>
<dependency>
<groupId>io.projectreactor</groupId>
<artifactId>reactor-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>io.projectreactor</groupId>
<artifactId>reactor-test</artifactId>
<!-- <version>3.4.14</version>-->
<!-- <scope>compile</scope>-->
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
<repository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<releases>
<enabled>false</enabled>
</releases>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
<pluginRepository>
<id>spring-snapshots</id>
<name>Spring Snapshots</name>
<url>https://repo.spring.io/snapshot</url>
<releases>
<enabled>false</enabled>
</releases>
</pluginRepository>
</pluginRepositories>
</project>
配置文件
这里我们只配置了r2dbc链接信息
r2dbc:
url: r2dbc:h2:mem:///test?options=DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
配置类
用于配置默认链接，创建初始化数据
package wang.datahub.springboot3demo.config;
import io.netty.util.internal.StringUtil;
import io.r2dbc.spi.ConnectionFactories;
import io.r2dbc.spi.ConnectionFactory;
import io.r2dbc.spi.ConnectionFactoryOptions;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import reactor.core.publisher.Flux;
import static io.r2dbc.spi.ConnectionFactoryOptions.*;
@Configuration
@ConfigurationProperties(prefix = "r2dbc")
public class DBConfig
private String url;
private String user;
private String password;
public String getUrl()
return url;
public void setUrl(String url)
this.url = url;
public String getUser()
return user;
public void setUser(String user)
this.user = user;
public String getPassword()
return password;
public void setPassword(String password)
this.password = password;
@Bean
public ConnectionFactory connectionFactory()
System.out.println("url ==> "+url);
ConnectionFactoryOptions baseOptions = ConnectionFactoryOptions.parse(url);
ConnectionFactoryOptions.Builder ob = ConnectionFactoryOptions.builder().from(baseOptions);
if (!StringUtil.isNullOrEmpty(user))
ob = ob.option(USER, user);
if (!StringUtil.isNullOrEmpty(password))
ob = ob.option(PASSWORD, password);
return ConnectionFactories.get(ob.build());
@Bean
public CommandLineRunner initDatabase(ConnectionFactory cf)
return (args) ->
Flux.from(cf.create())
.flatMap(c ->
Flux.from(c.createBatch()
.add("drop table if exists Users")
.add("create table Users(" +
"id IDENTITY(1,1)," +
"firstname varchar(80) not null," +
"lastname varchar(80) not null)")
.add("insert into Users(firstname,lastname)" +
"values('Jacky','Li')")
.add("insert into Users(firstname,lastname)" +
"values('Doudou','Li')")
.add("insert into Users(firstname,lastname)" +
"values('Maimai','Li')")
.execute())
.doFinally((st) -> c.close())
)
.log()
.blockLast();
bean
创建用户bean
package wang.datahub.springboot3demo.bean;
import org.springframework.data.annotation.Id;
public class Users
@Id
private Long id;
private String firstname;
private String lastname;
public Users()
public Users(Long id, String firstname, String lastname)
this.id = id;
this.firstname = firstname;
this.lastname = lastname;
public Long getId()
return id;
public void setId(Long id)
this.id = id;
public String getFirstname()
return firstname;
public void setFirstname(String firstname)
this.firstname = firstname;
public String getLastname()
return lastname;
public void setLastname(String lastname)
this.lastname = lastname;
@Override
public String toString()
return "User" +
"id=" + id +
", firstname='" + firstname + '\\'' +
", lastname='" + lastname + '\\'' +
'';
DAO
dao代码清单如下，包含查询列表、按id查询，以及创建用户等操作
package wang.datahub.springboot3demo.dao;
import io.r2dbc.spi.Connection;
import io.r2dbc.spi.ConnectionFactory;
import org.springframework.data.r2dbc.core.R2dbcEntityTemplate;
import org.springframework.data.relational.core.query.Query;
import org.springframework.stereotype.Component;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import wang.datahub.springboot3demo.bean.Users;
import static org.springframework.data.r2dbc.query.Criteria.where;
import static org.springframework.data.relational.core.query.Query.query;
@Component
public class UsersDao
private ConnectionFactory connectionFactory;
private R2dbcEntityTemplate template;
public UsersDao(ConnectionFactory connectionFactory)
this.connectionFactory = connectionFactory;
this.template = new R2dbcEntityTemplate(connectionFactory);
public Mono<Users> findById(long id)
return this.template.selectOne(query(where("id").is(id)),Users.class);
// return Mono.from(connectionFactory.create())
// .flatMap(c -> Mono.from(c.createStatement("select id,firstname,lastname from Users where id = $1")
// .bind("$1", id)
// .execute())
// .doFinally((st) -> close(c)))
// .map(result -> result.map((row, meta) ->
// new Users(row.get("id", Long.class),
// row.get("firstname", String.class),
// row.get("lastname", String.class))))
// .flatMap( p -> Mono.from(p));
public Flux<Users> findAll()
return this.template.select(Users.class).all();
// return Mono.from(connectionFactory.create())
// .flatMap((c) -> Mono.from(c.createStatement("select id,firstname,lastname from users")
// .execute())
// .doFinally((st) -> close(c)))
// .flatMapMany(result -> Flux.from(result.map((row, meta) ->
// Users acc = new Users();
// acc.setId(row.get("id", Long.class));
// acc.setFirstname(row.get("firstname", String.class));
// acc.setLastname(row.get("lastname", String.class));
// return acc;
// )));
public Mono<Users> createAccount(Users account) 以上是关于springboot3+r2dbc——响应式编程实践的主要内容，如果未能解决你的问题，请参考以下文章