r2dbc在Spring webFlux中怎么使用

这篇文章主要介绍“r2dbc在spring WEBFlux中怎么使用”，在日常操作中，相信很多人在r2dbc在Spring webFlux中怎么使用问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”r2dbc在Spring webFlux中怎么使用”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！

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。

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-h3</artifactId>        </dependency>        <dependency>            <groupId>com.h3database</groupId>            <artifactId>h3</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

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;@Componentpublic 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) {        return Mono.from(connectionFactory.create())                .flatMap(c -> Mono.from(c.beginTransaction())                        .then(Mono.from(c.createStatement("insert into Users(firstname,lastname) values($1,$2)")                                .bind("$1", account.getFirstname())                                .bind("$2", account.getLastname())                                .returnGeneratedValues("id")                                .execute()))                        .map(result -> result.map((row, meta) ->                                new Users(row.get("id", Long.class),                                        account.getFirstname(),                                        account.getLastname())))                        .flatMap(pub -> Mono.from(pub))                        .delayUntil(r -> c.commitTransaction())                        .doFinally((st) -> c.close()));    }    private <T> Mono<T> close(Connection connection) {        return Mono.from(connection.close())                .then(Mono.empty());    }}

controller

controller代码清单如下，包含了查询列表、按id查询，以及创建用户等操作

package wang.datahub.springboot3demo.controller;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.http.HttpStatus;import org.springframework.http.ResponseEntity;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.*;import reactor.core.publisher.Flux;import reactor.core.publisher.Mono;import wang.datahub.springboot3demo.bean.Users;import wang.datahub.springboot3demo.dao.UsersDao;@RestControllerpublic class UsersController {    @Autowired    private final UsersDao usersDao;    public UsersController(UsersDao usersDao) {        this.usersDao = usersDao;    }    @GetMapping("/users/{id}")    public Mono<ResponseEntity<Users>> getUsers(@PathVariable("id") Long id) {        return usersDao.findById(id)                .map(acc -> new ResponseEntity<>(acc, HttpStatus.OK))                .switchIfEmpty(Mono.just(new ResponseEntity<>(null, HttpStatus.NOT_FOUND)));    }    @GetMapping("/users")    public Flux<Users> getAllAccounts() {        return usersDao.findAll();    }    @PostMapping("/createUser")    public Mono<ResponseEntity<Users>> createUser(@RequestBody Users user) {        return usersDao.createAccount(user)                .map(acc -> new ResponseEntity<>(acc, HttpStatus.CREATED))                .log();    }}

启动类清单：

package wang.datahub.springboot3demo;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.context.properties.EnableConfigurationProperties;import wang.datahub.springboot3demo.config.DBConfig;@SpringBootApplication@EnableConfigurationProperties(DBConfig.class)public class WebFluxR2dbcApp {    public static void main(String[] args) {        SpringApplication.run(WebFluxR2dbcApp.class, args);    }}

到此，关于“r2dbc在Spring webFlux中怎么使用”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注编程网网站，小编会继续努力为大家带来更多实用的文章！